My first solar and battery backup system

R

Robert Crawley

Member
Joined
Jul 30, 2017
Messages
35
Hi everyone.

This is my first build and I am currently working on the design. I will welcome any input and recommendations on my design. I have included a basic outline of my plan below. I am not able to get exact power usage information on the 120VAC side because I am currently out of country on business. I am estimating that my max wattage needed at any given time will not exceed 10kW, but I will confirm when I return home (Southern Mississippi, Gulf Coast, USA).


image_hlysqg.jpg


I can't afford the cost to go completely off the grid, but my house has 2 breaker panels already. One is the 240VAC (H-N-H) Main Service with the meter, has breakers for all the 240 loads, and has a breaker that provides power to the 120VAC Aux breaker. The AUX breaker is where all my 120VAC gets distributed to the various circuits in the house. What I am planning to do is disconnect the 120VAC line from the Main Service and run it to my solar and powerwall build.

I want to use 4 x48VDC battery packs (18650 14S28P) in parallel to provide just over 10kWh of power. (This will be increased as time/funds allow).
I am planning on using 2 x 12AWG copper wiretwisted together for my bus bar. 24 AWG copper wireto connect the cells on the non-fused side (bottom)of the battery packs, and 34 AWG copper wire to make the fuses (top).

I want to use 8 x 340W solar panels to generate the energy. My roof only has one South facing side withenough room to accommodate 8 panels. At my location I can count on 4.5 Sun Hours averaged daily.

Where I need help:
Am I using acceptable wire gauge for my battery packs?
Does anyone have recommendations for battery chargers/inverters for my planned design?
Have I forgotten or missed something that I need to know before I start?

Thank you all in advance!!!
 
Welcome to the Powerwallers! :cool:

I see you've done your research before posting and asking questions. Kudos! :thumbs-up emoji:

In Fl, the main breaker box (metered; outside residence building) is really only intended for outside and heavy load use (central unit, separate building, etc). Even though it's a 240 panel, it has twin 120 rails. Same goes for your panel that is on the inside (usually in kitchen or garage) of the house. It has twin 120 rails and you use a 240 setup to get power to your heavy inside loads like the dryer, oven, etc.
So both panels should be rated for 240V max. Now, the inside panel may only be 200A, or less. The metered panel would be like 300 or 400A. The reason the sub-Panel would be 240V capable as well is to have balanced loads on each hot leg.
That was more for a clarification, more than anything else. Codes in Miss may be different on this, I dunno.

That's a good startup. 48VDC would give you minimal voltage loss and plenty of amps when needed (by the inverter). I'm going to assume you are going to build the packs with Serial and Parallel runs, then connect the packs in Parallel with each other. Are you going to do Parallel-Serial or Serial-Parallel in each pack (just curious about this configuration). Parallel-Serial is you have 14 single cells in series, then you hook each string in Parallel, then the packs in Parallel. Parallel-Serial is you have x-number of cells connected in Parallel, then those are in strings of 14 parallels, then the packs in parallel.

2 x 12 awg cables twisted is good. Just make sure they are tight. Several videos by AveRageJoe shows this process. There are others as well.
Getting a 48V inverter in the US is kinda hard. Well, sorta. Depends on what you're looking for. If you are wanting a Grid-Tie, then that's hard to find. If it's just a stand alone unit, then that's pretty easy. If you're wanting the Inverter to also charge, that makes it a little more difficult. I'm personally going to have two separate units for charging and for inverting for the bulk. As a backup source for charging, I'll be using some repurposed UPS's.

What are the voltages for the panels? Open and loaded voltages; rated amps; manufacturer; poly or mono-crystallines?

Again, welcome :)
 
Korishan,
Thank you for the feedback.
The 120VAC AUX panel was replaced earlier this year by an electrician friend of mine when i gutted and renovated my house, so I will check with him to verify (Thanks for catching that).
The plan for the battery packs is 14S28P, but I want to build a Proof of Concept pack first. I will use a vice clamp and drill to twist the two 12AWG wires together. I have seen a few videos of that working well.
This system will be completely isolated from the grid, so I'm looking at possibly using Aims inverter/charger (PICOGLF10KW48V240VS) which is rated at 10kW (30kW surge) and is 48VDC and will do 120/240VAC. Priced it online new at $2350.00 USD, Which looks like a good deal to me.
I haven't decided on the PV panels yet. I know I need 8x 340W panels and will go with the monocrystalin, but I haven't got much further than that.
 
RobertCrawley said:
Korishan,
Thank you for the feedback.
The 120VAC AUX panel was replaced earlier this year by an electrician friend of mine when i gutted and renovated my house, so I will check with him to verify (Thanks for catching that).
The plan for the battery packs is 14S28P, but I want to build a Proof of Concept pack first. I will use a vice clamp and drill to twist the two 12AWG wires together. I have seen a few videos of that working well.
This system will be completely isolated from the grid, so I'm looking at possibly using Aims inverter/charger (PICOGLF10KW48V240VS) which is rated at 10kW (30kW surge) and is 48VDC and will do 120/240VAC. Priced it online new at $2350.00 USD, Which looks like a good deal to me.
I haven't decided on the PV panels yet. I know I need 8x 340W panels and will go with the monocrystalin, but I haven't got much further than that.
Click to expand...

I don't have any experience with AIMS products, but if you're going to spend $2300, why not buy a proper inverter like a Magnum that's UL-listed, parallelable, split phase, etc?
 
I didn't think about it when I decided to use the UPS's for my inverters/chargers/gridtie(ish) setup. But, using those, they are at least UL listed and rated for the US power grid. So, I guess going that route, I'm in good company. Though, I wonder if the UL listing carries over when you alter the device :p
 
Korishan said:
I didn't think about it when I decided to use the UPS's for my inverters/chargers/gridtie(ish) setup. But, using those, they are at least UL listed and rated for the US power grid. So, I guess going that route, I'm in good company. Though, I wonder if the UL listing carries over when you alter the device :p
Click to expand...

I think you voided that as soon as you broke the "warranty void if seal broken" sticker ;)
 
Mike, thank you for the advice. I got too focused on one brand, and you are right. I need something that is UL approved and parallelable for future expansion. I will continue looking for an inverter/charger(s) that will meet my 10kW needs. I'm setting my max price point at $2500 USD, if you have any recommendations.

Korishan, you can buy new anti-tamper stickers online. Just make sure you completely remove the old one.
 
RobertCrawley said:
Mike, thank you for the advice. I got too focused on one brand, and you are right. I need something that is UL approved and parallelable for future expansion. I will continue looking for an inverter/charger(s) that will meet my 10kW needs. I'm setting my max price point at $2500 USD, if you have any recommendations.

Korishan, you can buy new anti-tamper stickers online. Just make sure you completely remove the old one.
Click to expand...

You would need 2.5x the Magnums then for 10kw. That's where I'm stuck at and the reason I haven't bought a good inverter yet. There very limited options for the US.

Also, pretty sure that's fraud. Lol ;)
 
The fridge and freezer is the last thing I would start with.
All I'm thinking of is cost of ownership.
When the solar don't work you loose 800 in food.
The water heater would be at the top of my list, They suck tons of power.
 
1958greyhound said:
The fridge and freezer is the last thing I would start with.
All I'm thinking of is cost of ownership.
When the solar don't work you loose 800 in food.
The water heater would be at the top of my list, They suck tons of power.
Click to expand...

Grey,
thanks for you advice. I will consider putting in a manual switch that would allow me to use grid power if solar and battery fail. Good Idea.

The 2 refrigerators and freezer are a constant load, and I want to make sure that the food doesn't go bad by having them on this system.

My water heater is an electric tankless on demandwater heater that uses 11kW (water heater). I don't want to put that much load on my system until I can upgrade it to handle 30kW and be able to go off grid completely.

mike said:
RobertCrawley said:
Mike, thank you for the advice. I got too focused on one brand, and you are right. I need something that is UL approved and parallelable for future expansion. I will continue looking for an inverter/charger(s) that will meet my 10kW needs. I'm setting my max price point at $2500 USD, if you have any recommendations.

Korishan, you can buy new anti-tamper stickers online. Just make sure you completely remove the old one.
Click to expand...

You would need 2.5x the Magnums then for 10kw. That's where I'm stuck at and the reason I haven't bought a good inverter yet. There very limited options for the US.

Also, pretty sure that's fraud. Lol ;)
Click to expand...

I'm thinking of using a 10kw Solar inverter systemMPPT solar charger 80A*2 (PIP 5048MS*2 in parallel). What do you guys think? This would allow me to expand my system in the future by adding additional inverters and will let me put my solar panels (I think) into separate strings facing different directions (1060 SqFt. house, small roof).

Please let me know what you guys think and if anyone is using a similar set up.
 
What I am planning for hot water is to tie in this heat exchanger that works with the HVAC.
I got quoted $230 for the unit.
Installation would be about $500 for me because I have an older r22 system.

https://www.doucetteindustries.com/Products/Residential/Aquefier-Residential

The other thing that I am looking at is a heat exchanger that fits into the drain line to preheat the water.

http://www.homedepot.com/p/Power-Pi...gclsrc=aw.ds&dclid=CNLG75GOu9UCFUKxTwodhEANvQ

I plan to make my own If i can get the pricing to work out.

I have a plumber that can install it because I want it to look neat and clean. I plan to get a backup preheat water heater that will work with both of the systems.

The drain line heat exchanger will preheat the water going into the preheat tank. And then the HVAC water heater runs a kidney loop with the preheat tank.

The combination of the two allows me to lower the HVAC electricity compressor current as well as the water tank energy usage.
 
Water pre-heater for the drain is easy to make. You just need a few pvc fittings/pipe, some adapters, and a metal pipe for the length of the heater. It may not be as efficient as the one from Homer, but it's a whole lot cheaper. And actually, you could probably build that exact same unit from copper pipe for less than $50. All it is is copper water line used in fridge water supply wrapped around another copper pipe. Real easy to make. The only thing that would be tedious is the actual wrapping of the pipe. After seeing this, I might actually change how I plan on doing mine.

Nice idea using the HVAC. It ends up doing double duty and saving electricity at the same time :cool:
 
RobertCrawley said:
1958greyhound said:
The fridge and freezer is the last thing I would start with.
All I'm thinking of is cost of ownership.
When the solar don't work you loose 800 in food.
The water heater would be at the top of my list, They suck tons of power.
Click to expand...

Grey,
thanks for you advice. I will consider putting in a manual switch that would allow me to use grid power if solar and battery fail. Good Idea.

The 2 refrigerators and freezer are a constant load, and I want to make sure that the food doesn't go bad by having them on this system.

My water heater is an electric tankless on demandwater heater that uses 11kW (water heater). I don't want to put that much load on my system until I can upgrade it to handle 30kW and be able to go off grid completely.

mike said:
RobertCrawley said:
Mike, thank you for the advice. I got too focused on one brand, and you are right. I need something that is UL approved and parallelable for future expansion. I will continue looking for an inverter/charger(s) that will meet my 10kW needs. I'm setting my max price point at $2500 USD, if you have any recommendations.

Korishan, you can buy new anti-tamper stickers online. Just make sure you completely remove the old one.
Click to expand...

You would need 2.5x the Magnums then for 10kw. That's where I'm stuck at and the reason I haven't bought a good inverter yet. There very limited options for the US.

Also, pretty sure that's fraud. Lol ;)
Click to expand...

I'm thinking of using a 10kw Solar inverter systemMPPT solar charger 80A*2 (PIP 5048MS*2 in parallel). What do you guys think? This would allow me to expand my system in the future by adding additional inverters and will let me put my solar panels (I think) into separate strings facing different directions (1060 SqFt. house, small roof).

Please let me know what you guys think and if anyone is using a similar set up.
Click to expand...


I have updated my plan to include a manual switch to allow to use grid power if it becomes necessary, and included emergency disconnects going to the inverter/charger(s). If anyone has ideas to improve on my design please edit my diagram and repost. I am always willing to listen.

I was wondering how peoples experience withPIP 5048MS inverters are like, and if they would recommend using them. I do not plan on being connected to the grid for this so my concern is more about performance and ease of use/setup.

Thanks in advance.

image_kqtxqo.jpg
 
Looks good i think. I dont see any major thing more than you should perhaps have fuses on the battery bank and to the PV array but perhaps already added? Also lightning protection on the PV array depending on where you live.
 
Looking at the PV Side of the project now, and my roof is less than great. The roof was replaced last year so it is structurally sound, but I don't have much room for South facing panels. Here is the roof of my house. I have included some rough measurements, and added numbers to mark off the different sections.


image_swtxgy.jpg


Section 1 is the only South facing part of my roof. I plan on putting my PV on that section, but I will need at least 24 panels to go off grid. I will most likely do 3 sections of 8 PVs.

I'm looking for ideas and recommendations on the best placement. I can't put the PVs in my back yard due to heavy shade there, and the front yard is off limits.
 
You could still put the panels on section 5, and probably 3 as well (though, it would only be most effective in the afternoon). In 5, it won't be optimal, but you could raise them so they are as pitched as the roof (don't want to go to far as for wind could pick them up; unless you were to build blocking under them), and then give them a slight tilt towards the south. Again, you won't get optimal, but at least you'd get something. Section 4 could be used as well, but that's the same story as 3. I think 2 is pretty much off limits.

The only issue with 5, other than odd tilt, is it looks like it gets shade in the morning. That's going to cause a lot of issues. Of course, that goes for 3 as well. 5 would give you a lot of real estate, though you would need to take care of that tree to get the best power from that location.
 
Korishan said:
You could still put the panels on section 5, and probably 3 as well (though, it would only be most effective in the afternoon). In 5, it won't be optimal, but you could raise them so they are as pitched as the roof (don't want to go to far as for wind could pick them up; unless you were to build blocking under them), and then give them a slight tilt towards the south. Again, you won't get optimal, but at least you'd get something. Section 4 could be used as well, but that's the same story as 3. I think 2 is pretty much off limits.

The only issue with 5, other than odd tilt, is it looks like it gets shade in the morning. That's going to cause a lot of issues. Of course, that goes for 3 as well. 5 would give you a lot of real estate, though you would need to take care of that tree to get the best power from that location.
Click to expand...

Unfortunately the tree that shades section 5 is not on my property, and it's a rental property so I can't talk to he owner about taking it down.

I think section 3 would be the best bet, generating power in the afternoon when the most power is used.
 
Ick. that sucks. Well, you could get some solar working. How's the wind in your area? You might wanna help supplement some influx with wind generation. The wind would be blowing first in the morning, and late in the evening. So it could give you a little boost. Even if it only ran for an hour in the morning and evening.
 
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