Help DIY solar generator

swampf0x

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Greetings all. If someone doesn't mind could you help me design a generator or complete smallish solar system big enough to run a deep freezer, big refrigerator, ceiling fan and a few lights along with moden, router, PC, TV and DVD player...... off grid. The bare necessities lol.

I've watched some you tube videos but haven't run across what I'm looking for. Everyone wants to use 100s of small batteries welded together. I want something easy to build, quick to build, and powerful enough for the above. Portable would be nice but not a have to have item.

Could I use 1 or 2 electric car batteries and a few Canadian Solar panels? How many? Should I use another brand? How many watts do I need to keep my batteries charged. What kind of battery should I get. Best other components like inverter, charge controller ect?

The panels will be ground mounted and cables ran 50' or so to the house.

Sorry to be so green but I figure you guys know alot more than I do.

thanks,
swampf0x
 
10kWh of battery
BMS
some fuses/breakers

An 2kW inverter preferable with built in MPPT solar charger
and a couple of solar panels.

This with cables, fuses and all other


Now the tricky question is that there are 100s of factors..: For instance money,, and what you can get hold of.

You can use Car batteries but its just not worth it since they wont last you long at all and you wont be able to run much of them more than for an hour or so before degrading them....


100% off grid? What type of weather or where do you live? So many questions
 
>10kWh of battery
Following up on @Daromer's post - you could achievea 10kWh lithium basedbattery with 16 x120ah LifePo4 cells in series (e.g. 48v nominal) OR 8 x 240ah LifePo4 cells in series (e.g 24v nominal) - which would take care of the 'many small batteries' issue. For solar charging - which is quitevariable by season / area - a1,000w-1,500w worth of panels for sunny summer/spring/fall mayget you in the ballpark.Of course - dead winter (low-sun/clouds all day)you need 5 times that in solar panels.

I would characterizeyourask as on thelarger side of solar generatorand verging on a smaller home system :)
 
You could also use EV batteries. This would be a huge jump forward in time needed to assemble everything. Again, you'd need to drop a lot of $$ to get them, though. You could easily drop $2k on an EV battery, depending on capacity size and SOH.
If you go this route, check your local salvage yards first. Then go to shipping, or driving long distances, to get them.
 
This started out as a way to stay comfortable and not loose food during a extended power outage. Then I got to thinking......Maybe I could build a small off grid system to power part of my home and still keep the power company for the big jobs. (I'm still in thinking stage/planning stage.)

I'm disappointed about the 6 Kwh solar panels needed for rainy/snowy wintery weather. As far as needing a lot of solar panels for winter............maybe. I'm in SW VA. I do have a 6000w generator to charge the batteries with, once in a while when needed. Maybe run it an hour or so a day??? I have no clue how this all works.

I like the idea of using 8 x 240ah LifePo4 cells in series (e.g 24v nominal) 8 is much better to hook up than 100s. How much will 8 cost me? I'm not pinching pennies but I don't want to waste money either.

Can you guys recommend a BWS and inverter?


Thanks everyone for the kind help.
swampf0x
 
Check out Batteryhookup and batteryclearinghouse they both have byd LiFePo4 batteries 24v think batteryclearinghouse is closer to sw VA but batteryhookup has what appear to be better batteries. The BYD batteries are ex commercial solar farm ESS/grid leveler systems. both offer free local pickup of batteries.

later floyd


2.5-3.5 kwh per 24v BYD LiFePo4 battery
 
The panels are meassured in kW not kWh.

Yes its not cheap and no you dont save any money of you plan for it to work year around. Just slightedt Cloud or Winter Monty degrades output alot. For instance the worst Winter Month i only get around 5% of the capacity of the panels. This just covers the losses in the system.....
 
swampf0x said:
This started out as a way to stay comfortable and not loose food during a extended power outage. Then I got to thinking......Maybe I could build a small off grid system to power part of my home and still keep the power company for the big jobs. (I'm still in thinking stage/planning stage.)

I'm disappointed about the 6 Kwh solar panels needed for rainy/snowy wintery weather. As far as needing a lot of solar panels for winter............maybe. I'm in SW VA. I do have a 6000w generator to charge the batteries with, once in a while when needed. Maybe run it an hour or so a day??? I have no clue how this all works.

I like the idea of using 8 x 240ah LifePo4 cells in series (e.g 24v nominal) 8 is much better to hook up than 100s. How much will 8 cost me? I'm not pinching pennies but I don't want to waste money either.

Can you guys recommend a BWS and inverter?


Thanks everyone for the kind help.
swampf0x

Hey there! One thing you could try is setting up some automation routines to minimize electricity usage and maximize storage+production. We use a weather APIon top of homeassistant for that. I'm originally from your neck of the woods and based on my experiences in the flat lands, should work just as well there!


daromer said:
The panels are meassured in kW not kWh.

Yes its not cheap and no you dont save any money of you plan for it to work year around. Just slightedt Cloud or Winter Monty degrades output alot. For instance the worst Winter Month i only get around 5% of the capacity of the panels. This just covers the losses in the system.....
The OP is in SW VA, they get far more daylight during the winter months than folks in Sweden. I'm not sure if OP is a totally lost cause for solar :)As I've mentioned, we use weather+ home automation to help adjust.

Edit: Removed product recommendation as it's a bit out of the spirit of the forum
 
>I'm disappointed about the 6 Kwh solar panels needed for rainy/snowy wintery weather. As far as needing a lot of solar panels for winter............maybe. I'm in SW VA. I do have a 6000w generator to charge the batteries with, once in a while when needed. Maybe run it an hour or so a day??? I have no clue how this all works.

Once you have a solar system with batteries... then yes, using a generator to charge the batteries works great. Say you create that10kwh battery bank and target a 60% DOD each day - that's 6kwh/day. You'll need 120v (or 240v) -> DC 48vcharging....

One option -several inverters (medium to higher price)include charging as afeature. For example, myAIMs 48v@2000w supports 20a of charging. But if we do the math -20a * 48v (battery) = 960w. Thegenerator would have to run 6hrs/day to get 6kwh of charge into the batteries. 6hrs/day, day after day is not trivial between oil changes, gasoline/propane etc. You can buy inverters with 'heftier' charging amps to reduce hours of generator run time - but I'm just saying you needto pay attention the charging amps and 'do the math'. Here's the chart showing charging amps for each AIMS model to give you an idea of 'pretty mainstream' amp capabilities:

image_vsilhz.jpg



Another option -You can buy (and hook in parallel) as many 120v -> 48vdc chargers the batteries can accept amps. I have 3 in parallel that can produce 2250w of charge - which I run from my 3000w Honda generator. You could buy as many as your generator can handle and reduce generator run time.

Panel option - IF you have room, extra panels actually make sense in the long term $ wise. Generators are expensive machines that wear, use fuel, are noisy, and require maintenance :)

Maybe start with generator / winter backup and then gradually expand panels?
 
Hey a local. LOL Pleased to meet you.

One of the places above has BYD 24v 8s Lifepo4 3kWh batteries listed. Could I use 4 of those? Start out as like a power wall for backup and use a few solar panels and a 6000w generator to charge a little each day using 4 chargers? Then add additional solar as I can.

Description says :

"If you get a module that tests 4 kWh that's a bonus. But we are pricing these as if every module was 50% of original capacity."

"Large lifepo4 modules are hard to keep in balance blow 3v per cell and above 3.4v per cell. Set your charge to 27v, discharge cutoff to 24v, and you will be very happy with the performance. Ride that discharge curve line and get very extended cycle life out of these. We check to make sure every cell has voltage and guaranteeing every cell has voltage and is still usable. We are not guaranteeing capacity but we tested a lot of these and realistic expectations are between 2.75-3.75 kWh out of the original 5.2kWh. We've priced these WAY BELOW the $100/kWh mark so worse case scenario its still an amazing deal."

"It is possible you will need to balance these. The ones we tested were stored discharged to around 2.8v and they would be a little out of balance but simply charging them up to 3.3v would balance them. We recommend the ISDT Q8 balance charger, its cheap and works amazing for this pack. Also you can easily add a Daly 8s lifepo4 BMS to this. The battery does not come with a BMS but the wiring is there and the sides pop out for easy access. The main positive and negative posts are easily accessible. You can always cut the posts, drill a hole in the main busbar leads, and simply add a nut and bolt. These are super easy to work on. No soldering needed to add a BMS. They are rack mountable. They can supply a crazy amount of amps so no worries about lack of power. Yes they are a little degraded but they have a ton of life left and at this price you can't go wrong. Maybe even add an active balancer but definitely use the batteries in the range of the discharge curve as shown. Large lifepo4 cells when fully charged typically drop in voltage. When we tested these they have been sitting for a while and still had good voltage so self discharging is not a concern although you will see self discharging when fully charged. They'll drop to 3.4-3.5v which is where they should be anyway as you can see with the discharge chart. You will lose some capacity but ultimately you want a setup that lasts many more cycles and stays balanced. Get them while they last!

Fully Charged voltage: 29.2v
Recommended fully charged operating voltage: 27v
Fully Discharge voltage: 20v
Recommended fully discharged operating voltage: 24v
Recommended max continuous discharge: 300a
Recommended max continuous charge: 150a
Weight: 125 lbs.
Dimensions: 20" deep x 17.5" wide x 6" tall"


Thanks guys you are a huge help for me.
 
Sounds like you're talking about this:https://www.batteryclearinghouse.co...volt-battery-pack-freight-shipping-bulk-rate2

An excellent youtuber @DavidPoz did a 48vbattery bank using several of these. There are a series of youtubes to give you a good 'handle' on them.Here's the first youtube:[size=small][size=small][size=small]htt[/size][/size][size=small][size=small]ps://youtu.be/i_V8v4APT60 S[/size][/size]everal morefollow that cover thecomplete build.[/size]

I think the rub with these is they test lower (from original specs)than people were hoping. That doesn't mean (especially for the price) that they can't serve as an excellent DIY powerwall build with much life left :).
 
I thought those BYD batteries are pretty decent until I saw the struggle DavidPoz has with them. First you need to find out what the capacity it is at and what they're claiming they have left. It's probably at around 65% of its full capacity. That in itself isn't great. It leads to issues like imbalance between the cells. DavidPoz spent time trying to balance them by linking them all together. The other issue are that the packs are welded together so rearranging each cell to get a nice pack is difficult. So you might need something like an active balancer that will keep the cells constantly in line. Some EV packs are like this so it does make it challenging to reuse them.
 
swampf0x said:
Is there a specific battery you'd recommend?

swampf0x

BatteryHookup is one of 'the truthful' / trustworthy sources - I've ordered 6,000 cells from them over 3 years. However you have to read plainly and not get to excited... (which I've done myself to my own shagrin). :)

They say in the description....
"....If you get a module that tests 4 kWh that's a bonus. But we are pricing these as if every module was 50% of original capacity. ...."
and further down
".... We are not guaranteeing capacity but we tested a lot of these and realistic expectations are between 2.75-3.75 kWh out of the original 5.2kWh. ...."

So they are being forthright that these are in the 50-60% SOH range. This is similar to the info we got on the@DavidPoz / batteries I referenced above.
Agree with @not2bme warnings. For a budget, it may be OK for you there are risks - maybe buy a couple'extra' so you can discard a really bad one of the group.


Recommendations......
Its tough. Patience is good and keep checking key sources.

Maybe consider Lithium-ion, like thesehttps://batteryhookup.com/products/complete-mercedes-oem-lg-chem-12s-44v-20ah-880wh BatteryHookup says "....We tested a dozen of these and they still have around 90% or better capacity ..." which is fine (in my opinion) for lithium ion. I believe this tear-downyoutube will give you insight into how to use them / maybe reconfigure into 14s-https://youtu.be/aZOpdxRCpOA

You could buy brand new LifePo4 such asBattleBorn or something like that. There's a channel where the guy reviews *many* LifePo4 cells and batteries you can checkout ... [size=medium]@DIY Solar Power with Will Prowse Can help you get a perspective on newer cells / pricing so you can judge better.[/size]
 
How about one of these https://watts247.com/product/pip-3048lv-mk/

Along with 12 of these https://batteryhookup.com/products/complete-mercedes-oem-lg-chem-12s-44v-20ah-880wh

And then I can add 6 solar panels like these https://www.solarelectricsupply.com...an-solar-superpower-cs6k-300ms-t4-solar-panel

I can build my own racking system once I get measurements. I can program it to turn on my generator when it gets to low

Would that make a good long lasting setup?
Did I miss any parts?
Could I get the 26% tax credit on all parts?


Looks like DavidPoz prefers the all in one now.
This set up would cost around $3000 if I don't need any more parts.
 
12s is not 48v most of its range is under 48v. The max and for most 48v inverters is ~60v min ~42v the one linked is 64v max 42v min
Missing BMS.

Later floyd
 
floydR said:
12s is not 48v most of its range is under 48v. The max and for most 48v inverters is ~60v min ~42v the one linked is 64v max 42v min
Missing BMS.

Later floyd
The youtube above shows that these can be taken apart and configured into 14s. 12 of them would be 144 cells, so 10 x 14s with 4 cells left over - and would be 10kwh battery bank.


swampf0x said:
How about one of these https://watts247.com/product/pip-3048lv-mk/

Along with 12 of these https://batteryhookup.com/products/complete-mercedes-oem-lg-chem-12s-44v-20ah-880wh

And then I can add 6 solar panels like these https://www.solarelectricsupply.com...an-solar-superpower-cs6k-300ms-t4-solar-panel

I can build my own racking system once I get measurements. I can program it to turn on my generator when it gets to low

Would that make a good long lasting setup?
Did I miss any parts?
Could I get the 26% tax credit on all parts?


Looks like DavidPoz prefers the all in one now.
This set up would cost around $3000 if I don't need any more parts.
Overall - you always need 'more parts' BMS, hardware, wire, electrical boxes, conduit, circuit breakers... $1000+- hard to guess without a lot more detail of your plans/situation:)

>Would that make a good long lasting setup?
Here's the famous, optimistic, Battery University chart (https://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries) that many of us are hoping is true for lithium-ion:)

image_yvudby.jpg


These Mercedesbatteries are lithium-ion (rather than LifePo4) so they will not last as long as LifePo4. In my case, I run lithium-ion but my battery is double-size so I can maintain a low50% DOD with hope of many1,000(s) of cycles (light blue line in chartabove - %75-25% DOD range). I amup to800 cycles so far with no noticeable degradation - so things are looking good but the data is just sketchy.

[size=small]If you do moderate DOD (70%?), then maybe 10yrs for these lithium-ion since they are 'auto based' and auto typically shoots for 10yrs with 80% capacity left. There's likelysome literature on the expected life of Mercedes Batteries.[/size]

"Long lasting..." is in the eye of the beholder. If you pay 1/2 price for 10yrs, you can buy 2 sets of batteries over 20yrs... many factors.
 
OffGridInTheCity said:
floydR said:
12s is not 48v most of its range is under 48v. The max and for most 48v inverters is ~60v min ~42v the one linked is 64v max 42v min
Missing BMS.

Later floyd
The youtube above shows that these can be taken apart and configured into 14s. 12 of them would be 144 cells, so 10 x 14s with 4 cells left over - and would be 10kwh battery bank.





swampf0x said:
I've watched some you tube videos but haven't run across what I'm looking for. Everyone wants to use 100s of small batteries welded together. I want something easy to build, quick to build, and powerful enough for the above. Portable would be nice but not a have to have item.


thanks,
swampf0x
I was just going by what was stated in the first post. Easy to build 2 24v LiFePo4 8s batteries just need to be connected in series that would be both easy and quick to build. hooking up the Bms wouldn't be hard either. you should have a 5 kWh battery. with just two batteries So 4 could give you up to 12 kWh. The cost is comparable with the LiFePo4 being quicker to have up and running. 1199.88 Mercedes LG vs 1100 BYD LiFePo4
Later Floyd
 
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