diy solar

diy solar

Please help me with panel placement

Maybe I'm confusing your application with someone else's who is using SolArk for battery backup.
Is yours strictly grid-tie, or will it provide backup during grid failure?
 
My panel is in the attached garage and there is no shut off outside by the meter. The garage and house are cinder block.

I am going to use batteries. I ordered 66 280a 3.2v EVE cells.
I will start with one 16 cell 48v battery.

Solardad has a Sol-Ark 12K and he is using 280a EVE cells too.
 
Looks like it supports just about everything one could want to do.


One function that is hard to come by is using 100% of available PV and then supplement with grid power, without cycling batteries.
I don't think inverters that use frequency shift to regulate production can do that when connected to the grid.
An on-line UPS that converts grid to DC and back to AC would, with less efficiency.
I think Enphase uses a different signalling method for zero-export which would accomplish it.

But so long as you can export and net-meter, this inverter should work.

"Sol-Ark 12K supports simultaneous DC and AC coupling up to a combined 16.5kW of PV"
Not sure how that's different from "Solar PV continuous power 12 kW"
"Inverter AC [DC] continuous power 9 kW [8 kW]"
Do you know if this uses frequency shift when off grid to control AC coupled inverters?
You're only planning a small amount on microinverters, the balance on Sol-Ark. On the protected side you can use the power produced by Sol-Ark inverter plus what is produced by AC coupled inverters. Shifting some panels to AC coupling would allow higher power draw (for a limited time, while battery has charge), or adding more panels would allow continuous draw, during the day. 8 kW is not bad, 16 kW is better.
 
I don't think inverters that use frequency shift to regulate production can do that when connected to the grid.
I assume this is a grid tie system with backup. Frequency shift would only be used when off grid. When on the grid excess would be sold so no need to modulate. Did i miss something?
 
Nothing missing.
Just not sure if his random panels with micro inverters go on the grid side or the protected side of Sol-Ark. If on the protected side, do these two play nice together?
There is a limit to how much power can go out the in wires of Sol-Ark and back to the grid. But a larger amount of power which can live on the protected side.
Same with my Sunny Island. US model can support 6.7 kW of AC coupled GT inverter (per SI) backfeeding the grid, but 12 kW if off grid.
European model can support 12 kW in both cases because same relay, same current, twice the voltage. So they can build a more capable grid-backup system.

He might be able to scale up the system somewhat.
If his AC coupled GT inverters are on the main panel, then when he flips the convoluted interlocked breakers I described, they will be transferred (after a polite delay) onto the output of Sol-Ark where they can let him have 12 kW or 16 kW of PV power while off grid. Even though that might be too much to backfeed to the grid through Sol-Ark.
 
SolArk has some limit on AC coupled and I think he got input on that from a vendor. Because of that I haven't weighed in on his electrical design or paid much attention to it.
 
Sol-Ark tech support told me it is more efficient to keep the AC coupled panels at about 20% of the total panels. But it is possible to AC couple 9600W. I saw one youtube of a guy that had all AC coupled panels and he liked it.
Sol-Ark is supposed to be very good at switching through all of the possibilities. They claim to be the fastest.
It is supposed to act as a UPS.
I haven't heard anyone complaining. I was planning to take their word for it.
 
Sol-Ark tech support told me it is more efficient to keep the AC coupled panels at about 20% of the total panels
I think that ratio would eliminate most of the issues raised by @Hedges because the SolArk can curtail its own solar faster when off grid. When on grid I do not recall your system design exceeded the capability of the SolArk. Since you had extensive discussions with SolArk and a vendor I did not pay much attention to those details.
I thought Hedges had some useful suggestions as far as upgrading your main panel.
 
Good it is flexible on AC and DC coupling.
Looks to me like there is a limit on total PV it can backfeed to the grid, while your 150A main breaker on a 200A or 225A panel allows more.
So I think it is possible for you to have maximum on Sol-Ark and significant additional AC coupled panels on your main breaker panel, not going through Sol-Ark. Within whatever limit your utility places on system size. During power failure you could flip some switches and have all the PV available.
Area for panels will be the primary constraint. The exact size of available space and of panels chosen will determine how many fit. And then, some panels are more efficient, more power for a given area. You don't appear to have filled all roof and awning area yet, maybe mixing portrait and landscape orientation could fit some more.
 
Looks to me like there is a limit on total PV it can backfeed to the grid, while your 150A main breaker on a 200A or 225A panel allows more.
That may be a constraint and one that I recently discovered with my Outback Skybox. My Skybox has has a limit of 5kW export to the grid even though I have almost 9 kW in panels connected. Much of that is derated by several factors. 5.7kW is going through a 3.8 kW AC coupled Solaredge inverter. Another 1.2 is some used panels that are west facing with shade and AC coupled micro inverters. They rarely put out more than 600 Watts. The balance of 2kW in panels are more west facing with some shade connected in series directly connected to the MPPT input of the Skybox. So far I have not seen evidence of any curtailment of solar production since I AC coupled the Solaredge 60 days ago.
I only discovered the constraint when i tried to increase the export limit past 5kW and that was as far as the setting went. I have never seen more than 4.8 being exported.
 
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The maximum the Sol-Ark will export to grid is 9000W. But I think that at the time solar production is highest is the same time my air conditioner is running the most. I don't think I will ever be wasting energy. My electric company has no limit on export to grid. And I have net metering.
 
Glad you clarified that. Now we can get back to the topic at hand, which is panel layout. With the low cost of panels and some economies of scale, I am a big fan of over panelling. I think some of the earlier suggestions to increase coverage by combining landscape and portrait orientations makes sense.
 
Q cell 330W


Pretty good efficiency, 330 W STC in 41 x 66 inches.
The Sunpower 327 I bought are 327 W in 41 x 61 inches, about 9% more.
PTC watts would be the thing to compare, but harder to find.

For now you have about 11880W STC (36 panels), will probably generate about 10 kW peak considering PTC and inverter efficiency.
That is enough to run a pretty large A/C, although later hours in the day you might be running partly on batteries. Lots of west-facing panels would help.

Since panels are cheap ($0.03 to $0.10 per kWh, amortized over just 10 years) over paneling and delivering more to the grid than you might use is economical, maybe a fraction of what you pay if you use more than you make.
 
Guys, Thanks for all of your help.
I have been thinking about this a lot. I have read this thread and my manual quite a bit and I still need to keep studying because this is difficult for me.
I pretty much decided to skip the A/C coupling for now. My usage doesn't seem to justify so many panels. And there is the 10K limit for the simplified permit and liability insurance. I have seen people go higher but I think it is simpler to just say below 10K of panels.
Also, the spot on the Sol-Ark were the A/C coupling connects is also used for something called Smart Loads or Programmable loads. I haven't even figured out what that means yet but I might not want to waste that spot.
Hedges says I can connect A/C coupled panels to the main electrical panel anyway.
There is a thread around that talks about adding panels later and it appears that I could probably do it without a permit if I decide I need more.
And getting a permit latter wouldn't kill me if I really needed it.
We don't even have the electric cars yet. And we don't drive much. Also, appliances and air conditioning seem to use less as we replace them. So, I am thinking electric usage should go down as time goes on.
Anyway here's my latest layout with no micro inverters but with optimizers. This makes it easy to have 3' on all edges. I have lots of questions about the electrical panel and important loads panel and I will get to that.

panel layout.png
 
Hedges says I can connect A/C coupled panels to the main electrical panel anyway.
I haven't looked at those details but at a high level you can always add panels to a grid tie system. Essentially they are AC coupled to the grid.

The most efficient way to use a hybrid inverter is to directly connect panels to the hybrid inverter. If I remember correctly there were some shade issues that suggested using some micros in shaded portions of your roof. In that case it would be easy easy to connect micros to your main panel. The only thing you would be giving up would be the production of the micros when the grid was down. Perhaps the details in @Hedges plan allowed the micros to be switched to the essential loads panel when the grid is down.
The only thing I can't tell from your latest plan is what kind of optimizers you are planning? If they are third party like Tigo they will work directly with a hybrid inverter and get you Rapid Shut Down compliance. In that case the latest plan sounds like a good one and eliminates the complexity of AC coupling micros.
 
My usage doesn't seem to justify so many panels. And there is the 10K limit for the simplified permit and liability insurance. I have seen people go higher but I think it is simpler to just say below 10K of panels.

The limit is probably 10 kW AC of inverters.
Normally about 12 kW STC of panels would be used, just reaching 10 kW AC on a typical day with optimum sun angle. Less other season and other times of the day.

You can "over panel", put up more panels so it clips a small amount of the time and produces more during other hours that it would with fewer panels.
I think that with multiple angles, about 18 kW STC of panels can be used on a 10 kW inverter without ever clipping. It gives you 50% more power during a given day. The extra 6 kW STC of panels might cost about $2000 (more or less, depending on model) There are used, UL listed panels available cheap you might add after initial system is complete. Rapid shutdown or optimizers run between $10 and $60 per panel (some models support 4 panels per shutdown box.)

Multiple strings of different angles can be paralleled on a single MPPT input, if all are the same length (similar total Voc & Vmp if different models).
If different length strings, should go to different inputs. Sunny Boy 5 kW and larger have 3 MPPT. A system with 2x SB 5.0 would have 6 MPPT. Have to check detailed specs for minimum voltage and maximum current per MPPT (or for paralleled MPPT.)
Solar Edge has optimizers per panel which allow multiple angles in a single string and up to 24 panels in series.
 
The limit is probably 10 kW AC of inverters.
Normally about 12 kW STC of panels would be used, just reaching 10 kW AC on a typical day with optimum sun angle. Less other season and other times of the day.

You can "over panel", put up more panels so it clips a small amount of the time and produces more during other hours that it would with fewer panels.
I think that with multiple angles, about 18 kW STC of panels can be used on a 10 kW inverter without ever clipping. It gives you 50% more power during a given day. The extra 6 kW STC of panels might cost about $2000 (more or less, depending on model) There are used, UL listed panels available cheap you might add after initial system is complete. Rapid shutdown or optimizers run between $10 and $60 per panel (some models support 4 panels per shutdown box.)

Multiple strings of different angles can be paralleled on a single MPPT input, if all are the same length (similar total Voc & Vmp if different models).
If different length strings, should go to different inputs. Sunny Boy 5 kW and larger have 3 MPPT. A system with 2x SB 5.0 would have 6 MPPT. Have to check detailed specs for minimum voltage and maximum current per MPPT (or for paralleled MPPT.)
Solar Edge has optimizers per panel which allow multiple angles in a single string and up to 24 panels in series.
Thanks again Hedges. Another reason I decided to go with 10K of panels is because it keeps things simple. I don't want to fail my inspection for something like too many panels or because my panels are too close to the line. And there is a qualifying question on the quick permit application that asks if my system has over 10K capacity.
I will get these up and decide later if I want to put up more panels.
I might decide to build a solar carport to charge our cars. Or I might be forced to build a shed to get my batteries away from the house then I could put solar on that.
The Sol-Ark has 2 MPPTs and each has 2 inputs. The manual says I don't need fuses if I use 4 strings or less. But I can add at least 2 more strings with fuses. With my new plan I will have 3 strings so I have plenty of room for expansion on the DC side. It seems like the limit on micro inverters that I can add is higher than I need to worry about.
And by not connecting micro inverters to the Sol-Ark, it opens up the Smart Load input which allows me to program loads based on battery level. That seems good for my hot water heater, stove and maybe a small window unit air conditioner.

I am fairly sure my electrical panel has a 225 amp busbar. I searched around and found people saying it is. But I still need to verify that.
And I am still deciding if it is better to do the line side tap. I can pay someone to do that for me if it makes sense. The Sol-Ark manual only talks about doing it if I have 2 Sol-Arks.

I am still trying to find an important loads (transfer switch?) panel like this -
If you know where I can buy one please let me know.

1601374428500.png
 
Here is a manual transfer switch. There are several models, different numbers of circuits:


I don't think you need line-side tap, even with two inverters, because it looks like you have 150A main and 225A busbar. If so, you could have two, 60A PV breakers.
Only benefit of line-side is you could have inverters hooked to the grid and serving as UPS for the entire house. But you might be told you could only have 40A of line-side tap (to avoid overloading utility drop if it fed maximum current to main panel and you had loads on the line-side tap)

By having your inverter connect to main panel with 50A or whatever breaker, and feeding a critical loads panel, you could use interlocked breakers to disconnect from grid and feed main panel with output of Sol Ark. That way any reasonably sized load in the house could be powered if desired. (maybe don't put that in until the rest is finished, to avoid confusing the inspector)
 
According to the Sol-Ark manual, I don't think I need a line side tap either. For some reason, Alt E put a line on my quote that says "Assumes lineside tap" I will ask them why they assume I would use a lineside tap.
I don't understand why you talk about having PV breakers in my electrical panel. The manual says to connect the PV directly to the Sol-Ark without breakers. I assume the Sol-Ark has it's own breakers.
I would love to be able to have a UPS for my whole house. But I am afraid. At this point I think it is better to use a important loads panel. I'd like to start with few important loads and add more loads one at a time. I like the idea of adding the interlock after I pass inspection. I don't know if I will ever try to run my 3.5 ton central air conditioner from batteries. It isn't important to me at this time. And like I said, I am afraid.
I am in a new to me house and I don't know how often the power goes out for extended periods. It has gone out a couple times. Once for a few hours because of what I think was a transformer blowing. I herd a familiar noise just before the power went out. Our utility wires are underground here. So even though we have hurricanes, I don't know if the power will go out for a long time. I lived on Long Island when Sandy hit and we were out of power for a long time. My whole neighborhood was under water and our power was out for weeks. I am close to the ocean now but at 65' elevation so I don't think we will ever be under water here.
 
When I said "PV breakers" I actually meant breakers backfeeding the grid with power that originated from PV.
If your system never exports power, doesn't matter where the SolArk connects to main panel. But if it does backfeed grid, the breaker wired to SolArk should be at the far end of the panel, away from the main breaker.

If your batteries and inverter can put out enough power to start the A/C (about 4 or 5 times the electrical rating on the A/C) for about 1 second, and if PV capacity is enough for the operating power of A/C, then it works. You would want what we call "load shed", so if battery state of charge gets below some threshold you turn the A/C off. My battery inverter has relays that can be programmed for state of charge. I'm using a setting of 70% DoD to disconnect, 50% DoD to reconnect. That disconnects everything. Later I'll use a different setting for A/C vs. critical loads. For now I turn off AC as the sun gets low.
 
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