OFF Grid Battery project for Solar and wind generator storage

KAOS247

KAOS247

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Sep 12, 2018
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11
Hiall,

I'm new to this and would just like to say thank you to soo many of you who have taken steps to document your progress andDIY approach,it has both helped and push me forward to do just the same.

If you have some time, please could you advise me on your thoughts of the following, I'm sure this article will help many others as well to have the information all in one place as I will summarisethroughout this thread when choices have been made and the project is being re-defined:


I am currently in my research phase of building my ownBattery packsand was hoping some of you fine folk would help answer some of thequestions I had.



What I am trying to achieve:

I.I would like to have atleast 150 KWh - 200KWhofcapacity.

II. Ability to deliver about 10KW -15KWof continuous draw use for more than 6hours at a time randomly through the week.

III. Space for the battery packsis NOT an issue BUT convenience is... so I don't want to have ONE BIG 20K cell battery LOL.

IV. Budget of about 25k (Not including Solar system or inverters, which has not been installed or chosen yet as I would like to build my solar system around what the best battery storage solution is first) (HoweverI'm looking to get an array of about 10 - 14KW of solar panels).




Question 1:

Scenario:
Lets say you have 20battery packs of X amount of cells each with the following spec 48v @ 1KW... I hope that's thecorrect terminology.

When you connect them all up in series OR parallel, you start with the first battery packand connect it to the second battery pack...BUT when you connect up the 3rd Battery pack... my QUESTION is....
Does the Connections (cable) between this 3rd batterypack and the second NEED to be of thickerAWG to accommodate battery pack 1 and Battery pack 2'scombined current during continuousload times? and if this is the casewould Ineed to step up my cabling thickness between all thebattery packs going forwardas I scale up the battery pack numbers, all the way up to the powerdelivery terminal point?

Question 2:
Are using ACTUAL fuseson the positive ends of the batteries cell pointsworth doing? like theseGlass-Fuse-Tube-Axial-With-Lead-Wire-Fast-Blows-Fuse On EBAY

AND if they are, how would I know which fuse I would need per cell for a given Battery Pack voltage (12v, 24v ,36v, 48v)built up of newbatteries? how do I work this out? 1 amp, 1.5 amp, 3 amp, 5 amp? these fuses are rated for 250v AC no?

Question 3:
Battery pack configuration.
a.What is the best battery pack voltage to use 12v, 24v, 36v, 48v? given the choice of inverter and the SIZE of storage I would like up to 200 KWH
b. What is the best configuration of batteries to use in your chosen voltage for pack building?
c. What method did you go with in your own battery packs?
c. What are the pros and cons for your choice?

One of the things I'm am looking at is to minimisethe effort required to swap out a dead cell. is there any way to do this. I have been trying to come up with a solution of how to build the battery pack without soldering... so just using contacting surfaces

Question 4:
What 18650 battery is the best to use for these 3 areas:safety,reliability and CAPACITY ;)?
I will be buying them brand NEW... as I don't see the point in putting ALL this effort and HARD work(long hours) into soldering and making these battery packs to only have to tear them down within a year because a single old used cell has gone bad... and whats even worse (From MY understanding, I could be wrong)is that if more than a 3 - 4 of these individual 18650 batteriesfail(go bad)in a packthen if you wish to continue using this pack thenyouwill lower your entire capacity draw from the rest of the battery packs you have, to avoid further damage to those packs. OR the voltage drop would be too much for that bad battery pack it would be unusable.
Please correct me here.

Question 5:
Batteries,I have my eyes set on using 18650 batteries like many of you :)

Which ones should I go with, keeping in mind I will be buying them BRAND NEW from what I hope will be a reputable supplier on Alibaba or factory direct:

LG HG2 3000mAh 20A
Sony VTC6 3000mAh 15A
Panasonic NCR18650B 3400mAh 4.9A
Sony VTC5A 2600mAh 25A
Samsung 36G 3600mAh 10A
Samsung 30Q 3000mAh 15A
Samsung 20S 2000mAh 30A
Vapcell (VTC5D) 2800mAh 25A
Samsung 25R 2500mAh 20A
Sony VTC4 2100mAh 30A


I have put them in order of the ones that I am looking at top being the most likely and the bottom one being the less likely choice, Please feel free to reply rearranging the order for what you think is best to least.



I have done quite a bit ofresearch but speaking to pros like you lot on here will definitely give me peace of mind of the choices of hardware I make going forward and it'salways easier to change your mind when working on paper than after making the purchases :)

I appreciate all you help in advance

Many thanks
Sam
 
Q1) Cables stay the same based on the current draw needed and string voltage. The higher the voltage, the thinner the cables due to less current needed overall. So from pack to pack is the same size. This is the same size as the absolute ends.

Q2) Fuses are rated based on how many amps you'll pull from each cell once the pack is assembled. If you plan on pulling 100A, and you have 100p, then each cell is 1A. So you'd want fuses that will pop around 3A. This is due to resistances and safety factors.
You can go with 1A fuses, but they may blow sooner. Or you can go with 5A fuses which will take a little longer, but may not blow when you need them to. But, this is based on how much current you need.
The more strings (full 14s, or whatever, setups), the lower each cell will dish out. So if you have 1x14s100p @ 100A, each cell is 1A. But if you have 2x14s100p, then each cell is .5A. etc, etc, as you add more strings.

Q3) a) this is a loaded question. The best is the one that best suits your needs with the given types of cells. If you use standard LiIon cells, then stay away from 12/24V if possible. You loose a lot of possible capacity. 36/48/etc will work great with LiIons. If you use LiFePO4's or LTO's, then you can easily do the 12/24 without any issues.
But remember, the lower the voltage, the higher the amp draw, the larger the cables. And cables can be expensive really quickly.
b) I'm assuming you are referring to 14s100p vs 14s50p vs someother config. This is really up to you and your space allotment and how easy you want to move the packs (or how strong/nimble you are)
c) I plan on replaceable cell design. This will use cell holders. Each cell will be monitored so I can detect cells that are becoming weak and I can remove them before they cause an issue. I have plenty of space to do this task
d) With my design, it just takes up more space, will probably cost a little more in the end. But, if something goes wrong and a cell goes bad, I don't have to destroy a whole pack to figure out which one is the bad one. I'll know by looking at my graphs.

4) This one I will let someone else answer as I'm not sure. If you are buying brand new, though, I would recommend LiFePO4 or LTO's. A bit pricey up front, but a whole more more flexible in pack design, voltage ranges, and inverter hookups.
 
For that amount of storage, I'd re-consider what batteries you're going with. If you grab some packs from electric vehicles you'd only have dozens of batteries to work with instead of thousands. Going Off Grid on Youtube is a good example of what that could look like.
 
Korishan said:
Q1) Cables stay the same based on the current draw needed and string voltage. The higher the voltage, the thinner the cables due to less current needed overall. So from pack to pack is the same size. This is the same size as the absolute ends.

Q2) Fuses are rated based on how many amps you'll pull from each cell once the pack is assembled. If you plan on pulling 100A, and you have 100p, then each cell is 1A. So you'd want fuses that will pop around 3A. This is due to resistances and safety factors.
You can go with 1A fuses, but they may blow sooner. Or you can go with 5A fuses which will take a little longer, but may not blow when you need them to. But, this is based on how much current you need.
The more strings (full 14s, or whatever, setups), the lower each cell will dish out. So if you have 1x14s100p @ 100A, each cell is 1A. But if you have 2x14s100p, then each cell is .5A. etc, etc, as you add more strings.

Q3) a) this is a loaded question. The best is the one that best suits your needs with the given types of cells. If you use standard LiIon cells, then stay away from 12/24V if possible. You loose a lot of possible capacity. 36/48/etc will work great with LiIons. If you use LiFePO4's or LTO's, then you can easily do the 12/24 without any issues.
But remember, the lower the voltage, the higher the amp draw, the larger the cables. And cables can be expensive really quickly.
b) I'm assuming you are referring to 14s100p vs 14s50p vs someother config. This is really up to you and your space allotment and how easy you want to move the packs (or how strong/nimble you are)
c) I plan on replaceable cell design. This will use cell holders. Each cell will be monitored so I can detect cells that are becoming weak and I can remove them before they cause an issue. I have plenty of space to do this task
d) With my design, it just takes up more space, will probably cost a little more in the end. But, if something goes wrong and a cell goes bad, I don't have to destroy a whole pack to figure out which one is the bad one. I'll know by looking at my graphs.

4) This one I will let someone else answer as I'm not sure. If you are buying brand new, though, I would recommend LiFePO4 or LTO's. A bit pricey up front, but a whole more more flexible in pack design, voltage ranges, and inverter hookups.
Click to expand...

Thanks buddy, this really helps me out :)

I have been looking atLiFePO432700 cells, but they don'thave many holders or supported holder hardwarefor them yet (readily available that is)I was thinking of these becauseyou can get them with screw terminals so they can be swapped out quickly too ALSO they have a cycle life of about 2000 recharges. the positives for this choiceare very good :)

Only downside is that there are hardly NO videos or youtubers on their pack building with these so the learning curve is very big (for me that is anyway) that's the ONLY thing that would make it hard for me to try DIY this.


Many thanks

Mazlem said:
For that amount of storage, I'd re-consider what batteries you're going with. If you grab some packs from electric vehicles you'd only have dozens of batteries to work with instead of thousands. Going Off Grid on Youtube is a good example of what that could look like.
Click to expand...

True, I have been looking into buying used Tesla car batteries but they are very expensive.. they cost around 17k for a 90KWh battery made of 18650 cells (second hand)... whenI could buy 20'000 (for less trhan 20k) 18650 Brand new with over 200KW of power.

The cooling aspect of the Tesla batteries is amazing, as it has liquid cooling ... BUT again, have you seen the videos of people trying to strip it apart WITHOUT destroying thepackaging ... IMPOSSIBLE to do so... hence why I was not really fond of that approach especially with the outlay of 17k for a complete battery with NO WAY to swap out bad cells.

I have seen some really good options for32700 Batteries and their capabilities but also like I said earlier there are hardly anyone using these batteries so my DIY would be very troubling with very littler guidance from the youtubers experiences

Many thanks :)
 
Sizing
KAOS247,
I'd like to confirm your requirements as the system you've specified is a very largescale and I want to check that you are not over specifying the system. Can you answer the following please?
1. What is your average ENERGYusage per 24 hour day in kWh?
2. What is your peak ENERGYusage per 24 hour day in kWh? Ie a busy day running washing machines orother high energy usage appliances which are not normally used.
3. What is your peak POWER usage in kW?
4. What is your location? Approx latitude longitude or country and locale of you are shy. I assume UK.
5. What direction will your solar panels face? What degree of shading? What angle shall they be installed? Building integrated or free standing?
6. How many days of autonomy do you require during periods of poor solarweather?
7. Do you have options for any other energy sources such as wind or hydro?
8. Is this system off grid or grid tied?
9. You say that you need 10-15kW for 6+ hours. That's 60 to 90kWh. What do you power that requires that much? I assume this is light commercial and three phase 400v? What type of load - ie motors, computers, heating, lighting? Are phases load balanced or can one have significantly higher than others?
Tim
 
If your able to buy 20,000 cells (200kWh) for less than 20k then your being sold fake cells.

17k for 90kWh Tesla pack is 188/kWh
Your budget of 25k for 150kWh is 167/kWh - optimistic...
How is the Tesla pack very expensive in comparison ?

I'm guessing you rin the UK and this is a commercial setup.
 
w0067814 said:
Sizing
KAOS247,
I'd like to confirm your requirements as the system you've specified is a very largescale and I want to check that you are not over specifying the system. Can you answer the following please?
1. What is your average ENERGYusage per 24 hour day in kWh?
2. What is your peak ENERGYusage per 24 hour day in kWh? Ie a busy day running washing machines orother high energy usage appliances which are not normally used.
3. What is your peak POWER usage in kW?
4. What is your location? Approx latitude longitude or country and locale of you are shy. I assume UK.
5. What direction will your solar panels face? What degree of shading? What angle shall they be installed? Building integrated or free standing?
6. How many days of autonomy do you require during periods of poor solarweather?
7. Do you have options for any other energy sources such as wind or hydro?
8. Is this system off grid or grid tied?
9. You say that you need 10-15kW for 6+ hours. That's 60 to 90kWh. What do you power that requires that much? I assume this is light commercial and three phase 400v? What type of load - ie motors, computers, heating, lighting? Are phases load balanced or can one have significantly higher than others?
Tim
Click to expand...

Hi Tim

I am over specifying the system as I want to be off grid most of the time and NOT switching back togrid. So if I can get a good 65% - 75% off grid that would be good for me.

The reason whyI have chosen that figure is because it is a BIG number hehe, but reallybecauseI would like to try move away from gas heating too if I can(or as much as I can)so that I can have electric heaters at times or like a Hot air ventilation system that uses electric including cookers too.



Usage...Please don't judge me :shy:(I am trying to go green):

My average day uses about 75KWunitssporadically across the day including all the thingsthat are juston all the time (alarm, CCTV, NAS, Network hubs, light sensors,Home Automation, chargers, SKY box, Koi Pond)

hot water cylindertank is on for 3.5 hours every day and is rated at 2.7 KW

(in the future)I would like to have a BEEFY home entertainment system too, which would have about 7-10 KWh power need, hence the over specifying)

I'm not sure how I would average all the aboveout (other than adding it up and dividing by 24 hours (would that be correct)


Location:

I'm located in XYZ(not sure what the latitude longitude)and have a fairly big T shapedpitched roof, I also have 2 additional detached singlegarages with pitched roofs which I would like tosolar panel up also.

I know that on some of my roof I will not get a LOT of sunlight but even so I would still solar it up as daylight will still generate some measly small amount ofpower. See attached for top down view and arrow for sun movement in summer.

https://ibb.co/nXYZ

Setup of Solar panel:

This is something I would let the professionals like you guys tell me :) have NO idea about these details other than I KNOW that3/4 of my roof is hit with sunshine for about 8 hours of the day in summer and in winter less so :/



Other power options

I have a ok sizekoi pond that has a powerful return pump (12000 UK Gallons per hour = 3.4 Gallons / Second). I'mnot fussed on the looks of the waterfall just the sound of water falling (if that makes sense) SO I wanted to fit a hydro turbine on the return for the pond so that I can also generate power from there to supplement my needs. I have beenthinking of a way to buy one of those large hydroPermanent magnet generators and try hook that up to the pond return. not sure yet asits just a crazy thought though.

Power Grid

I have 3 Phase power at my house due to previously having a waste pumping station on my property (it's been taken over by Thames water now...SO I STILL have the 3 PHASE in myhouse but I am only using 1 line;)SO I can use Commercial equipment for the solar panels.. its a shame I do not have a LARGE garden other wise I would make a small solar panel area also.


Thanks Tim for your reply,I hope you can help me make sense of some of the choices I need to make for my power storage needs :)

Regards
Sam
 
Sam, are you expecting any form of financial return on what will be a significant investment ?
 
completelycharged said:
If your able to buy 20,000 cells (200kWh) for less than 20k then your being sold fake cells.

17k for 90kWh Tesla pack is 188/kWh
Your budget of 25k for 150kWh is 167/kWh - optimistic...
How is the Tesla pack very expensive in comparison ?

I'm guessing you rin the UK and this is a commercial setup.
Click to expand...

I'm in the UK and this is for a home... I just lucked out and have a 3 Phase installed in my house.

I am trying to get some people together to bulk buy from manufactures, I know few e-cig vape shops and have been in conversations with them also, as they do NOT buy this many cells they don't get as good a price BUT if I ADD my 20K cells to each Vape shops5k cell order they would benefit huge as it's WIN WIN for them they make BIGGER margins on the batteries when selling to E-vapers.

BUT regardless you can bulk buy from Alibaba for less than a $1 a cell if you buy more than 10K cells

There are LOADS of fakes out there I am aware but there a few on Alibaba who are legit companies and are (Ibelieve) official producers for these batteries... I think these cells do not have ONE factory making them.. there are a few I thinkthat are official and are licensed to produce these cells for each brand/make.


I could be VERY wrong but the way I was looking at it:

The tesla pack is expensive and could be very labour intensive down the road if cells go bad especially when they have been hammered by the vehicle before hand so we would not know the expectancy of each of the cells without tearing it apar

Also the cost is 17k for a second hand battery ... 90Kwh which WILL require liquid cooling as the Tesla batteries are insulated with the packaging and require liquid cooling when under load.

The Tesla BatteryIS THE quicker way to go I give you that but I think I can get MUCH more storage and power with buying new batteries than buying 1 single Tesla battery.


With 20k = $26312.84

lets say minus $4312.84k for tax and import

Lets say you buy batteries for exactly $1 (Ihave a feeling you will be able to get them cheaper then that but lets just say $1)

that will get you 22'000 cells NEW which would give you MUCH more KWH than a single Tesla 90KWh battery

PLUS the added benefit of hopefully using a battery system that allows easy swap out of cells with minimum tear down.



Ps.

I have a fair bit ofmanufacturing experience and can say with some certainty that manufacturers make HUGE profits due to their markups on their product. (stack em high sell em cheap)

AND given that 18650 have a lot of competition even amongst the official manufactures the prices can be negotiated MUCH lower than you think especially when you buy lets say 20K - 40k cells in ONE order and have a promise to buy more in the future of similar OR evenLARGER size order... truth be said is something I would consider if I felt that doing this project for myself was easy and performed as intended. I would happy to considerpartnering up with somesmart people like yourselves and see if we could turn this little forum thread into something more ;) Anyway We're getting off topic haha

Sean said:
Sam, are you expecting any form of financial return on what will be a significant investment ?
Click to expand...

Yes and NO... LOL if that makes sense... As long as I can eliminate my monthly electric bill OR at least cut it in half I'd be happy...

Currently I have a bill of about average500 -600 a MONTH FML lol

Looking at my current bill I would be able to make a good dent into it with my battery and solarinvestment

lets say its costs roughly 45K for battery and Solar setup total

My yearly bill for electric is about 7200

45/7.2 = 6.25 years I would of broke even if I was COMPLETELY covering my monthly bill

OR

45/ 12.5 years I would break even if I was ONLY saving HALF my monthly elec bill

I know these calculations are VERY crude so lets just add 4 years onto each (Ihope that is enough LOL)

so that's 10.25 years OR 16.5 years to break even.

MY understanding is very VERY limited to this so I am probably wrong so please correct me.
 
Summer with 10kW of solar you will get around 30-40kWh output, about half your daily useage (if it is 75kWh) so you may need to go larger with the solar and less large with the battery.... You possibly need closer to 30kW of solar and about 60kWh of battery but you dont seem to have the space for 30kW of solar. 30kW of solar will give you less than 10kWh some days in winter and over 100kWh mid summer, still only just over your daily average, not much to charge a battery with.

Moving away from gas - install a heat pump, either ground source or air source as this when powered by solar would be economically cheaper than gas on a p/kWh heating basis. When powered via battery (cost per kWh of storage added on) then the cost or type of your cells become critical and 18650's may not work out cheaper than gas.

Hot water - if your all electric for hot water look at getting a larger (1000 litres or multiple of) hot water cylinder installed and use the solar output directly to heat this, use the cylinder as a thermal store - sort of a hot water battery. If the hot water is regular use then this can be "charged" when the sun is shining rather than putting the power in a battery to discharge later... try to avoid heating water from a battery pack appart from the kettle.. 1,000 litres of water heated from 23C to 60C takes 43kWh (effectively a big battery).

For solar, will this be on a Feed In Tariff arrangement ? If it is then the requirements for charging the battery from solar is different and you can't go off grid as it has to be connected 24x7 for the export meters to work. Then you need to have a charger inverter unit to charge and discharge the battery, something like the Victron Miltigrid. Export payments then make charging a battery pack more expensive if they change the deemed export value (as expected once the smart metering rollout is complete) to actual exports as your power value is the seeign a 5p/kWh difference.

If it is not on a FIT and your staying sort of off grid then multiple charge controllers directly into the pack (main busbar), however the distance from the battery location can become an issue, so you may need to run the HV DC from the solar panels to where you battery is and have the charge controllers at that location. Normal solar installs have grid tied inverters within a few meters from the end connections of the solar string, with a low voltage DC battery running the power longer distances at low voltage can give a lot of looses or very big cables.

Different more complex option is to use grid tied inverters and island your house from the grid and run it with a separate large inverter, but you don't have enough solar to island the house.

If you go above 4kW in total capacity of the inverter(s) connected to the grid then you need to notify the grid before connection and it has to be an approved type and have installer details. DIY install of a 10kW inverter is not going to pass, unless it is islanded then yours to do as you please, unless it then invalidates your house insurance cover for fire.....

Roof mounting - the south facing roof has a steeper angle and will be better for winter. Do the lower portions get shade in winter from next doors roof mid winter ? Shadowing can drop the output a lot (my 2kW of panels on one section giving below 100W with blue sky and full sun due to them being in the shadow of a tree). The garage on the left would appear to be almost fully shaded appart from mid summer so I would say not viable for panels. The one on the right will get some output but will be shaded a lot of the time, possibly good for a couplf of panels to the right of the window. You do appear to have a decent amount on the east and west facing roof sections, more on the west. If your self installing and no FIT then I would even contemplate putting some panels near flat on the dormer sections on the western side if you get the panels cheap enough.

For the battery, build it from smaller packs around 2-5kW per pack and connect these to a common bus as you add them. The common bus is then were you connect everything else to, so the battery only sees the bus, nothing else and it does not really care what else is connected. Build and grow as you need.

Avoid even thinking of going 3 phase, metering costs are not worth it, 415V to deal with and a DIY install of a 10kW inverter 3 phase will never get DNC approval.

For your economics to pay the best bang for the buck you really need to go large solar and a battery less than 2x the size of your solar install. Charging the battery from the grid (off peak to peak pricing in the UK is not wide enough) is not really viable and you will never get enough sun in the day to provide a days worth of power so the battery becomes a short term within day buffer.

$1 per cell you are not going to get quality, anything but. Small manufacturer needed about 50k cell order before they would talk, with a dodgey cell specification and no actual cycle life testing.... Tesla is below $1 per cell but they are making more cells than the rest of the industry put together and do not sell them externally. Small shop, 2x that at least.

Import will be about 1k door to door for 2 pallets and then you have duty and 20% VAT and crossed fingers they turn up. For 20k cells you would need some credit guarantees and shipping insurance on top, otherwise hand over all the cash and wait over a month for the goods to turn up...
 
KAOS247 said:
I.I would like to have atleast 150 KWh - 200KWhofcapacity.
Click to expand...

Not trying to judge anybody , But more than 50,000 connections (18650) and all be good ?

Could you share some of those strange tea leaves , that have in your cup of tea

100 ah LIFePo4 , A lot less connections , bolt together

LTO will last longer than you will

Jim
 
JimJr. said:
KAOS247 said:
I.I would like to have atleast 150 KWh - 200KWhofcapacity.
Click to expand...

Not trying to judge anybody , But more than 50,000 connections (18650) and all be good ?

Could you share some of those strange tea leaves , that have in your cup of tea

100 ah LIFePo4 , A lot less connections , bolt together

LTO will last longer than you will

Jim
Click to expand...


People do assemble large banks of 18650s. Take a look in the Cell Counter! Would take a while to assemble, but if you have the time and the batteries, why not?
 
50,000 connections * 3 seconds per connection / 60 seconds / 60 minutes = 41.66 hours. Not that long overall, actually. Just wouldn't want to do it in one session, tho :p
 
Lol Yea my limit at the soldering iron is about 200 connections in a stretch. then I gotta get up off my ass and give my brain a rest
 
This project will never happen, its just what happens when folks spend far to long dreaming about the YouTube videos they watch for a few minutes.

Add some professionally qualified help with the design and installation, along with 100K and it might (pointlessly) get past the day dreaming stage.
 
KAOS247,

This is going to be long, and full of information, so read it all. Don't skip, and read it twice.

What I am about to write feel like I am raining on your parade and may dent your pride, but please take it with the positive light that it is intended. God knows, I've had ideas examined to the N'th degree and condemned by many people. Sure it hurt at the time, but most of the time when I look back they are right an it's saved me embarking on a project that is likely not to have the outcome Iwanted. Given the sums of money you are talking about, you certainly want to get it right.

You clearly like your technology as you mention many advanced things like "alarm, CCTV, NAS, Network hubs, light sensors,Home Automation, chargers, SKY box, Koi Pond" however I get the feeling that whilst you may operate it at the consumer levelyou do not necessarily understand it at and engineering level. Make no mistake! Powering your own home, especially one that is off grid, is an engineering project. And by that, I do not mean soldering stuff together, but rather the maths and design that must come before any component is purchased.


In your posts you mention a number of things that appear to be conflicting, or at least confused. For instance, you mention that you use 75kWh per day average usage. This works out at 75kWh * 365 days =27,375kWh per annum. Later you mention that your electricity bill is 7,200 per annum. If we take 15 pence per kWh as the cost of electricity (about average for UK 2018) and work back to how much energy you would need to consume in order to cost that much,then we get 7,200 / 0.15^-1 =48,000kWh. That's 131 kWh per day!So which is it?... or are you really paying 7,200 / 27,375 kWh = 0.26 per kWh? If so then you need to switch energy supplier!

The UK average electricity usage for all purposes excludingheating is 3,300kWh per annum. For a larger family home this average rises to about 4,600kWh per annum. A friend of mine has what I consider to be a very large usage at 7,000 kWh per annum. I use 4,200kWh per annum in a house which is occupied all day4 days per week, and morning /evenings for 3 day per week with a family. As an engineer / geek I have a lot of technology, some of which (servers, routers etc)runs 24/7.

Space heating in winter is extremely variable between houses as many factor like age, insulation, windows, construction technique andsize all make a difference. However to give a couple of points for reference, my 96m (1,033 ft)semi detached house uses 12,000kWh of gas for both heating and domestic hot water. My 196m (2,110 ft) house uses 20,000kWh. In both cases the hot water demand accounts for about 2,000kWh of those totals.

So your demands could be in the right ball park if we assume you are using electricity for heating usingresistance heaters, however if you use gas then your usage is way out of line with what would normally be accepted for a domestic residence.

So we have two scenarios:

Electrical Heating
Installing solar shall have little effect on reducing heating bills as the time when you need heat (winter) coincides with the lowestsolar insulation. You shall import from the grid heavily in winter even with a massive array. Solar in winter may produce just 10% of your heating demand. Instead you should be on a multi-rate electricity tariff where there are times of cheap rate electricity. You should be using that opportunity to store heat in a thermal store of later use during the day when prices are higher and your demand is higher. If you heat using electricity then you shouldn't be using resistance heating, but rather a heat pump. Resistance heating has a Coefficient of Performance (COP) of 1.0, meaning that you get 1 unit of usable heat out for every 1 unit of electricity in. A heat pump by comparison can have a COP as high as 6, meaning that for every unit of electricity in, you get up to 6 units of heat out. Now, in reality you shall rarely see COPs as high as this in the UK due to our oceanic climate where winter temperatures hover just above zero with heavily moisture laden air. In spring and Autumn you may, but Winter shall be much lower. A poorly specified or installed heat pump may even end up with a COP approaching 1.0 or possibly lower as ice builds up on the coils and then requires electrical resistance heating to thaw it out. Not really an issue in much of Europe or USA where winter humidity is low, but a real problem in the UK where winters are damp.

Electricity costs approximately 4.5 times that of gas (15p vs 3.3p per kWh approx) so unless your heat pump can achieve an average COP of 4.5 across the whole year then you shall be better off with gas heating unless you have no choice.

Turning high grade energy in the form of electricity into low grade heat is not a good use of energy. The UK grid is only about 38% efficient.

Insulate,Insulate,Insulate!

Gas Heating
If you are using gas heating, and the figures you gave are just for electricity, then your usage is grossly above normal. You should take the following steps:

  1. Ascertain that your meter is reading correctly. Turn off all switches at the fuse board except for a single one that supplies plug sockets to a smallest section of the property as possible to minimize ghost loads. The garage or kitchen is good. Then turn off all sockets on that ring main. Observer the meter and ensure that is is not registering any consumption. Then turn on one load of 2 - 3kW such as a portable electric resistance heater. Observer the meter over a period of time such as 15 minutes. Ensure that the metered amount of energy used is as expected. Ie 2kW * 0.25 hours = 0.5kWh. Increase the time to get a more accurate reading.
  2. Take an energy audit to see what loads you have. It might be worth consulting an specialist given the sums of money you are spending on energy as it shall pay for itself within a few months. Make a list of all loads noting their power requirements and the amount of time the run per 24 hours. Multiply the two to find the energy requirements per day. This may be a long list. Compare the results to your historical metered usage.

    Bare in mind that each 1 watt of electricity that is used 24/7 equates to 8.76kWh per annum, or about 1.30. So multiply the power of your 24/7 loads in watts by 1.3 to get the cost in per annum. A pond pump can soon add up!

  3. Ensure you are on a competitive energy tariff for your usage, and time of use. Given the amount you use I expect you should have a dedicated account manager, perhaps from the small business team. You should be able to negotiate a better deal that Joe public.
  4. Armed with your knowledge from your audit start making changes to your usage, starting with the highest energy users first (note that this might not the the same as the highest power appliances!) It will follow the 80/20 rule, in that 80% of your savings shall come from just 20% of your effort. Saving that last 20% is hard work.
---
Pond
You mention you have Koi pond. I can almost guarantee that your pond is over pumped as it seems to be the thing with Koi enthusiasts on the forums. You mention your pump moves 12,000 UK gallons. That's 54 tons per hour, or 1,309 tones per day. The equivalent of moving a multi-story car park full of cars! Concentrate on improving the efficiency of filters rather than just pumping harder.

Consider replacing your pumps. Either with smaller, correctly sized pumps, or with 3 phase pumps and a variable speed drive (VFD) as this shall allow you to buy an over sized pump and then turn down the wick until you reach the correct level. The cost savings from VFD pump control can be huge and pay for the investment very quickly.

PS: you cannot generate electricity from the pond return. The energy in the return is being supplied by the pump. Better just not to put that energy there in the first place.

Hot Tub?
If you have a hot tub you should really get it plumbed into the gas central heating via a stainless steel heat exchanger rather than using the electrical heater that was supplied with it. Electrical heaters are under powered - typically 3 - 5kW - and as a result take a day to heat the hot tub. A gas boiler by contrast will typically be 25 - 60kW and can heat the tub in 30 minutes! This allows you to turn the tub off and allow it to cool whilst not in use, and then heat it just prior to use (perhaps automated from an app that readies your tub as you commute home). The thermal losses (and thus cost) are proportional to the difference in temperature between the water and the air. If you can bring that temperature gradient down when the tub is not in use the losses shall be reduced. There is an old wives tale that leaving your heating on 24/7 is better than just turning it on when you need it. That is total carp! Turning it off when not required will always be more efficient.

Air conditioning?
You have domer rooms upstairs so they may be hot in summer and cold in winter. Super insulate the roof as this shall benefit at both times of year. Air conditioning is expensive to run, especially if you are just throwing the heat away outside. First of all reduce the heat load with insulation, and consider blinds or shades (external if you can) for the windows on sunny days. Lastly, can you utilise the waste heat from air conditioning to heat a hot tub or pool?

Heating
You should be using gas! You have gas already. Heat pumps are in vogue, and they are great compared to electricalresistance heating, and shall achieve a saving against oil, but compared against gas they do not score so well. The cost to install, service and maintain a heat pump is far higher than a gas boiler, and this must be factored in. Don't be fooled by marketing hype.

Hot Water
The energy usage for hot water comes from two sources: The amount of hot water drawn off, and the standing losses of the tank. Consider a combi boiler to eliminate the standing losses. Insulate the tank otherwise. Keep the max temperature to 65C. This reduces standing losses, and allows your boiler to work in condensing mode at ~85% efficiency rather than ~50% for noon-condensing.Change the shower heads to low flow types, but be sure you get one that aerates the water so it comes out like bubbly champagne. This way you will not notice the reduction in flow so much. My shower uses just 4L per minute, yet I have had guests comment on how nice the shower experience is.

Once you've got a handle on your usage, then you can look at power wall / other power options. Before then it a waste of time, hence why I have not answered any technical power wall questions.

Good luck!

-Tim
 
JimJr. said:
KAOS247 said:
I.I would like to have atleast 150 KWh - 200KWhofcapacity.
Click to expand...

Not trying to judge anybody , But more than 50,000 connections (18650) and all be good ?

Could you share some of those strange tea leaves , that have in your cup of tea

100 ah LIFePo4 , A lot less connections , bolt together

LTO will last longer than you will

Jim
Click to expand...

I have been considering LIFePO4 batteries but as I want to try this DIY project myself it is some what hard for me to do this by myself without that many videos available on youtube to provide decent guidance :)

I agree the life of the batteries is a biggie for me

Thank you for theMAD maths for the soldering, I am NOT looking forward to that if I ever use 18650 batteries LOL

Sean said:
This project will never happen, its just what happens when folks spend far to long dreaming about the YouTube videos they watch for a few minutes.

Add some professionally qualified help with the design and installation, along with 100K and it might (pointlessly) get past the day dreaming stage.
Click to expand...

I'm sure you may have 100K sitting under you mattress but I don't ... that is one hard matress;)

I will get professional help but I like to learn my subject first fromothers who have experience like yourselves, so I will get ideas and KNOW when the time comes what to ask for and what not to get.

WHY make the same mistake as someone else when they can happily explain to you why it was a mistake and what they would of done instead?

I'll be the first to admit when I do not know something.. and my friend I DO NOT KNOW ANYTHING ABOUTTHIS SUBJECT. hence why I want the widest advice available.
 
Your daily consumption of 75kwh is high, even by US standards, and we know how to waste energy. An average home here is around 35kwh, so you're double it. You mentioned you have a oversized water pump, but do you know how much that costs? If you have a 3HP motor and you run it 24hrs it could take upwards to 40kwh a day to run it just to hear water falling.

I'd say put together a list of your major usages. Some you can read off the back of the panel like your pump that runs continuously, some you can't. For example a fridge may say 800W, but it's only 800W 5% of the time. Get a kill-a-watt or equivalent to see where all your power is going to. Then you work the math and see where all this power usage is going to. It's worth studying it first than to throw money on solar panels instead of being more efficient.
 
w0067814 said:
KAOS247,

This is going to be long, and full of information, so read it all. Don't skip, and read it twice.

What I am about to write feel like I am raining on your parade and may dent your pride, but please take it with the positive light that it is intended. God knows, I've had ideas examined to the N'th degree and condemned by many people. Sure it hurt at the time, but most of the time when I look back they are right an it's saved me embarking on a project that is likely not to have the outcome Iwanted. Given the sums of money you are talking about, you certainly want to get it right.

You clearly like your technology as you mention many advanced things like "alarm, CCTV, NAS, Network hubs, light sensors,Home Automation, chargers, SKY box, Koi Pond" however I get the feeling that whilst you may operate it at the consumer levelyou do not necessarily understand it at and engineering level. Make no mistake! Powering your own home, especially one that is off grid, is an engineering project. And by that, I do not mean soldering stuff together, but rather the maths and design that must come before any component is purchased.


In your posts you mention a number of things that appear to be conflicting, or at least confused. For instance, you mention that you use 75kWh per day average usage. This works out at 75kWh * 365 days =27,375kWh per annum. Later you mention that your electricity bill is 7,200 per annum. If we take 15 pence per kWh as the cost of electricity (about average for UK 2018) and work back to how much energy you would need to consume in order to cost that much,then we get 7,200 / 0.15^-1 =48,000kWh. That's 131 kWh per day!So which is it?... or are you really paying 7,200 / 27,375 kWh = 0.26 per kWh? If so then you need to switch energy supplier!

The UK average electricity usage for all purposes excludingheating is 3,300kWh per annum. For a larger family home this average rises to about 4,600kWh per annum. A friend of mine has what I consider to be a very large usage at 7,000 kWh per annum. I use 4,200kWh per annum in a house which is occupied all day4 days per week, and morning /evenings for 3 day per week with a family. As an engineer / geek I have a lot of technology, some of which (servers, routers etc)runs 24/7.

Space heating in winter is extremely variable between houses as many factor like age, insulation, windows, construction technique andsize all make a difference. However to give a couple of points for reference, my 96m (1,033 ft)semi detached house uses 12,000kWh of gas for both heating and domestic hot water. My 196m (2,110 ft) house uses 20,000kWh. In both cases the hot water demand accounts for about 2,000kWh of those totals.

So your demands could be in the right ball park if we assume you are using electricity for heating usingresistance heaters, however if you use gas then your usage is way out of line with what would normally be accepted for a domestic residence.

So we have two scenarios:

Electrical Heating
Installing solar shall have little effect on reducing heating bills as the time when you need heat (winter) coincides with the lowestsolar insulation. You shall import from the grid heavily in winter even with a massive array. Solar in winter may produce just 10% of your heating demand. Instead you should be on a multi-rate electricity tariff where there are times of cheap rate electricity. You should be using that opportunity to store heat in a thermal store of later use during the day when prices are higher and your demand is higher. If you heat using electricity then you shouldn't be using resistance heating, but rather a heat pump. Resistance heating has a Coefficient of Performance (COP) of 1.0, meaning that you get 1 unit of usable heat out for every 1 unit of electricity in. A heat pump by comparison can have a COP as high as 6, meaning that for every unit of electricity in, you get up to 6 units of heat out. Now, in reality you shall rarely see COPs as high as this in the UK due to our oceanic climate where winter temperatures hover just above zero with heavily moisture laden air. In spring and Autumn you may, but Winter shall be much lower. A poorly specified or installed heat pump may even end up with a COP approaching 1.0 or possibly lower as ice builds up on the coils and then requires electrical resistance heating to thaw it out. Not really an issue in much of Europe or USA where winter humidity is low, but a real problem in the UK where winters are damp.

Electricity costs approximately 4.5 times that of gas (15p vs 3.3p per kWh approx) so unless your heat pump can achieve an average COP of 4.5 across the whole year then you shall be better off with gas heating unless you have no choice.

Turning high grade energy in the form of electricity into low grade heat is not a good use of energy. The UK grid is only about 38% efficient.

Insulate,Insulate,Insulate!

Gas Heating
If you are using gas heating, and the figures you gave are just for electricity, then your usage is grossly above normal. You should take the following steps:

  1. Ascertain that your meter is reading correctly. Turn off all switches at the fuse board except for a single one that supplies plug sockets to a smallest section of the property as possible to minimize ghost loads. The garage or kitchen is good. Then turn off all sockets on that ring main. Observer the meter and ensure that is is not registering any consumption. Then turn on one load of 2 - 3kW such as a portable electric resistance heater. Observer the meter over a period of time such as 15 minutes. Ensure that the metered amount of energy used is as expected. Ie 2kW * 0.25 hours = 0.5kWh. Increase the time to get a more accurate reading.
  2. Take an energy audit to see what loads you have. It might be worth consulting an specialist given the sums of money you are spending on energy as it shall pay for itself within a few months. Make a list of all loads noting their power requirements and the amount of time the run per 24 hours. Multiply the two to find the energy requirements per day. This may be a long list. Compare the results to your historical metered usage.

    Bare in mind that each 1 watt of electricity that is used 24/7 equates to 8.76kWh per annum, or about 1.30. So multiply the power of your 24/7 loads in watts by 1.3 to get the cost in per annum. A pond pump can soon add up!

  3. Ensure you are on a competitive energy tariff for your usage, and time of use. Given the amount you use I expect you should have a dedicated account manager, perhaps from the small business team. You should be able to negotiate a better deal that Joe public.
  4. Armed with your knowledge from your audit start making changes to your usage, starting with the highest energy users first (note that this might not the the same as the highest power appliances!) It will follow the 80/20 rule, in that 80% of your savings shall come from just 20% of your effort. Saving that last 20% is hard work.
---
Pond
You mention you have Koi pond. I can almost guarantee that your pond is over pumped as it seems to be the thing with Koi enthusiasts on the forums. You mention your pump moves 12,000 UK gallons. That's 54 tons per hour, or 1,309 tones per day. The equivalent of moving a multi-story car park full of cars! Concentrate on improving the efficiency of filters rather than just pumping harder.

Consider replacing your pumps. Either with smaller, correctly sized pumps, or with 3 phase pumps and a variable speed drive (VFD) as this shall allow you to buy an over sized pump and then turn down the wick until you reach the correct level. The cost savings from VFD pump control can be huge and pay for the investment very quickly.

PS: you cannot generate electricity from the pond return. The energy in the return is being supplied by the pump. Better just not to put that energy there in the first place.

Hot Tub?
If you have a hot tub you should really get it plumbed into the gas central heating via a stainless steel heat exchanger rather than using the electrical heater that was supplied with it. Electrical heaters are under powered - typically 3 - 5kW - and as a result take a day to heat the hot tub. A gas boiler by contrast will typically be 25 - 60kW and can heat the tub in 30 minutes! This allows you to turn the tub off and allow it to cool whilst not in use, and then heat it just prior to use (perhaps automated from an app that readies your tub as you commute home). The thermal losses (and thus cost) are proportional to the difference in temperature between the water and the air. If you can bring that temperature gradient down when the tub is not in use the losses shall be reduced. There is an old wives tale that leaving your heating on 24/7 is better than just turning it on when you need it. That is total carp! Turning it off when not required will always be more efficient.

Air conditioning?
You have domer rooms upstairs so they may be hot in summer and cold in winter. Super insulate the roof as this shall benefit at both times of year. Air conditioning is expensive to run, especially if you are just throwing the heat away outside. First of all reduce the heat load with insulation, and consider blinds or shades (external if you can) for the windows on sunny days. Lastly, can you utilise the waste heat from air conditioning to heat a hot tub or pool?

Heating
You should be using gas! You have gas already. Heat pumps are in vogue, and they are great compared to electricalresistance heating, and shall achieve a saving against oil, but compared against gas they do not score so well. The cost to install, service and maintain a heat pump is far higher than a gas boiler, and this must be factored in. Don't be fooled by marketing hype.

Hot Water
The energy usage for hot water comes from two sources: The amount of hot water drawn off, and the standing losses of the tank. Consider a combi boiler to eliminate the standing losses. Insulate the tank otherwise. Keep the max temperature to 65C. This reduces standing losses, and allows your boiler to work in condensing mode at ~85% efficiency rather than ~50% for noon-condensing.Change the shower heads to low flow types, but be sure you get one that aerates the water so it comes out like bubbly champagne. This way you will not notice the reduction in flow so much. My shower uses just 4L per minute, yet I have had guests comment on how nice the shower experience is.

Once you've got a handle on your usage, then you can look at power wall / other power options. Before then it a waste of time, hence why I have not answered any technical power wall questions.

Good luck!

-Tim
Click to expand...

If youlisten carefully... you will hear my dream crashing and burning!... thank you HAHA jk!



Your advice is sage, I must admit.

My 75KW was froma reading I did the other day it could just be much lower usage on that day My unit cost WAS 14.6p and was recently put up to 15.3p per unit in August... NOW we just got ANOTHER letter saying that it is going up again to 18.7p per unit in November and will be fixed from then onwards !!! BS I say, they will keep on increasing the price until we are drained of all. I'm with BULB they are the cheapest by far in my area.


Also just to confirm I am a NOVICE at electrics this iswhere I am getting stuck with the electrical calculations and requirements BUT IamVERY skilled withcrafts and my ability to learn very quickly and put in hard grafthencewhy the DIY approach.

Soldering and wiring is not an issue for me as it is(I think)simply a process that youfollow... flux... soldier... flux... solder... OR I would get solder with flux coatingand just clean of the terminal ends before applying;)



I've just had a smart meter installed (this is what has opened the flood gates to home automation andlooking into making my home as much off grid as possible)

I am not using 75KW an hour (75 KWH) I'm using about 75kw units a day roughly...does that make sense? OR does that not make sense!

Sorry I made a oversight the figure I gave (600 a month included my gas too so if we remove gas then my electric is on average about 400 a month)

As I want to get rid of as MUCH gas usage as possible too that's why I included my complete monthly bill as I was trying to consolidate the calculations if that made sense.


HOT WATER
I have an immersion tank - whichis a hot water tank with a heating element inside (about 2.7 KWH)that provides my house with hot water.

The energy transferenceof HEAT using electric OR gas(I find hard to calculate)...
ie. how would you know how many units of gas you are using to produce how many units of heat and compare that to using electric to produce heat as a substitute?
This is one of the reason why I have tried to over size my batteries so that I can try to go as much off grid as possible (electric cookers &electric central heating)


POND:
PLEASE NOOOOO,I love my pond LOL... one of the small joys in life I guess...when I say it's "ok size" I mean it's pretty big about 9000 UK gallons and houses 27(1.5-2 ft koi)... a lot of waste is produced and needs to be removed also it requires airation at timeshence why the pump circulation is so high.

I was thinking of setting up a water mill where the water is returned (instead of a waterfall I would have the water mill turning) that was hooked up to a PMG motor that would have a high output (50 - 100 KW with a RPM of 300... with gearing ofcourse), I've seen some on Alibaba that seem to have some REALLY good output levels.

Using a 3 phase pump, this does SOUND very good ... I not sure why I didn't think of this... however I tried googling it for about 20 mins and I couldn't find anything that would work.

Needs to beSelf - primingand be able to handle pond debris.


My filters are pretty good at removing all the muck but maybe I could look at that ... potentially change the type of filter... There are some really good filters in the market now days drum filters and they are very efficient so maybe that would help and I wouldn't need as much turn over so could use less powerful pump(s)... worth a investigation for sure.


OTHER:
I don'thave aHot tub ORAir conditioning ... I live in England UK... cold and wet is life here on a regular bases HAHA!


ELECTRICAL HEATING vsGAS:
I was thinking of HOT AIR ventilation system that uses electric for home heating... I have a friend who has one that uses gas and the hot air heats up his house VERY quickly... obviously insulation insulation insulation WILL be required and is something I am prepared to do with this project


Thank you for your deep insight, I will take on board what you have said and will definitely need to see where I can make the adjustments... especiallywith my energysupplier if I find a better rate somewhere else... thisBREXIT is going to destroy us with energy prices!

I think Iwill definitelybe charging thebatteries at theoff peekhours to help also.So maybe once every few days I would charge them all off peek and use them that way... supplemented by the solar when they can,that would be a good start I think.



Many thanks for you input, I really do appreciate your effort in writing all that out:)

Regards
Sam

I just had a cool idea...


One of the biggest issues with these types ofbatteries is the over heating during high draw...

So if youwere to find a good sweet spot in size of total battery packs counts you had then you could IN THEORY deliberatelyreduce the number of battery packs you have to find that sweet spot with and therefore be able to use the heat produced during drawto ALSO heat your home

Pretty much like the Tesla battery but it would plumbed into your house central heating.

So you would have all the radiators in your house act as heat sinks for your Tesla imitationBattery


I think for that to be more viable you would need a HUGE array of Solar panels to constantly provide full charges lol

But just a thought :)

completelycharged said:
Summer with 10kW of solar you will get around 30-40kWh output, about half your daily useage (if it is 75kWh) so you may need to go larger with the solar and less large with the battery.... You possibly need closer to 30kW of solar and about 60kWh of battery but you dont seem to have the space for 30kW of solar. 30kW of solar will give you less than 10kWh some days in winter and over 100kWh mid summer, still only just over your daily average, not much to charge a battery with.

Moving away from gas - install a heat pump, either ground source or air source as this when powered by solar would be economically cheaper than gas on a p/kWh heating basis. When powered via battery (cost per kWh of storage added on) then the cost or type of your cells become critical and 18650's may not work out cheaper than gas.

Hot water - if your all electric for hot water look at getting a larger (1000 litres or multiple of) hot water cylinder installed and use the solar output directly to heat this, use the cylinder as a thermal store - sort of a hot water battery. If the hot water is regular use then this can be "charged" when the sun is shining rather than putting the power in a battery to discharge later... try to avoid heating water from a battery pack appart from the kettle.. 1,000 litres of water heated from 23C to 60C takes 43kWh (effectively a big battery).

For solar, will this be on a Feed In Tariff arrangement ? If it is then the requirements for charging the battery from solar is different and you can't go off grid as it has to be connected 24x7 for the export meters to work. Then you need to have a charger inverter unit to charge and discharge the battery, something like the Victron Miltigrid. Export payments then make charging a battery pack more expensive if they change the deemed export value (as expected once the smart metering rollout is complete) to actual exports as your power value is the seeign a 5p/kWh difference.

If it is not on a FIT and your staying sort of off grid then multiple charge controllers directly into the pack (main busbar), however the distance from the battery location can become an issue, so you may need to run the HV DC from the solar panels to where you battery is and have the charge controllers at that location. Normal solar installs have grid tied inverters within a few meters from the end connections of the solar string, with a low voltage DC battery running the power longer distances at low voltage can give a lot of looses or very big cables.

Different more complex option is to use grid tied inverters and island your house from the grid and run it with a separate large inverter, but you don't have enough solar to island the house.

If you go above 4kW in total capacity of the inverter(s) connected to the grid then you need to notify the grid before connection and it has to be an approved type and have installer details. DIY install of a 10kW inverter is not going to pass, unless it is islanded then yours to do as you please, unless it then invalidates your house insurance cover for fire.....

Roof mounting - the south facing roof has a steeper angle and will be better for winter. Do the lower portions get shade in winter from next doors roof mid winter ? Shadowing can drop the output a lot (my 2kW of panels on one section giving below 100W with blue sky and full sun due to them being in the shadow of a tree). The garage on the left would appear to be almost fully shaded appart from mid summer so I would say not viable for panels. The one on the right will get some output but will be shaded a lot of the time, possibly good for a couplf of panels to the right of the window. You do appear to have a decent amount on the east and west facing roof sections, more on the west. If your self installing and no FIT then I would even contemplate putting some panels near flat on the dormer sections on the western side if you get the panels cheap enough.

For the battery, build it from smaller packs around 2-5kW per pack and connect these to a common bus as you add them. The common bus is then were you connect everything else to, so the battery only sees the bus, nothing else and it does not really care what else is connected. Build and grow as you need.

Avoid even thinking of going 3 phase, metering costs are not worth it, 415V to deal with and a DIY install of a 10kW inverter 3 phase will never get DNC approval.

For your economics to pay the best bang for the buck you really need to go large solar and a battery less than 2x the size of your solar install. Charging the battery from the grid (off peak to peak pricing in the UK is not wide enough) is not really viable and you will never get enough sun in the day to provide a days worth of power so the battery becomes a short term within day buffer.

$1 per cell you are not going to get quality, anything but. Small manufacturer needed about 50k cell order before they would talk, with a dodgey cell specification and no actual cycle life testing.... Tesla is below $1 per cell but they are making more cells than the rest of the industry put together and do not sell them externally. Small shop, 2x that at least.

Import will be about 1k door to door for 2 pallets and then you have duty and 20% VAT and crossed fingers they turn up. For 20k cells you would need some credit guarantees and shipping insurance on top, otherwise hand over all the cash and wait over a month for the goods to turn up...
Click to expand...


MAN ALIVE this is AMAZING information buddy!

I will deffo GET A PRO to install my solar setup this is something I am NOT willing to risk .. as I have the 3 phase power connection, I will see what the quotations will be.

But all of the solar stuff will be done by the pros given the price is right approach :)

This is one of the reasonswhy I want to find out about creating my OWN DIY power wall battery storage too. So that I can save on buying the SOLAR PROVIDERSPUNY BATTERY and canpair up the solar installationwith the type of battery I will need to make, so that I can simply request bigger capacity hardware for the battery management and FIT.I don't REALLY care about the FIT but if it's on the table as an option and DNC areok and the price is OK... who knows.

I have been researching and it seems that I will need to look at 48v Solarsystem like you said with HV DC... this gives me the direction in which my storagebattery pack buildswill need to be also ( I hope :)

I plan on using a BMS system to monitor my battery packs. In theory if I DO get a FIT in place I would ONLY EVER want it to sell the power I generateAFTERmy batteries are fully charged as the GRID pay you JACK SHIT for your KW i'd rather charge my batteries with it... hence not fussed if I don't get a FIT... but judging by MY power usage I don't think I will EVER have any spare elec to sell back LOL

Also will the FIT system register my battery storage as a use of power or willit deplete my batteries back to the grid?


Cheap batteries
A few people have said this also about not getting the cells cheap, but I think it's possible with buying power.

My family business has a fair bit of experience with import export with vehicle car components so this wouldn'tbe an issue for me BUT finding a reputable source will be .. I have a few but just hope they are TRUE :)

I think I will tryuse my batteries in the short term at least to charge from the grid during off peak hours and then use them in the day. at least that wayIcan lower my unit costing per KW with a larger battery. my off peek price is about 9 KW/unit

and using NEW cells would allow me to do this with minimum loss of power transfer... I THINK LOL

Many thank for your reply buddy,a LOT of really good information and guidance.

Regards
Sam
 
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