Rebuilding a solar system

[ArtDeco]

I have had a grid tied system for about 10 years, and recently had a fire ( apparently caused by my ebike batteries) that destroyed my garage and most of my home.

No loss of life, no one hurt, but both inverters (SMC 3500w Sunny Boys) were destroyed, we had to gut the house, put on a new roof, order all new furniture, fixtures, appliances, and so forth.

We are rebuilding and salvaged 18 250 watt panels (that tested at 36 volts) out of the 24 we had, and want to reuse them with a modern 4 or 5 kw inverter and battery backup system able to run a deep well pump, fridge and freezer, and some low draw items like led lights, fan, and phone charger during outages. There are no installers still in business locally, although there were several 10 years ago.

I am looking for suggestions for inverter, charger, and batteries , so my contractor/electrician and I can salvage a system.
Edit I will not be using lithium batteries for some reason.

 

[BentleyJ]

Very sorry you experienced the fire and so much property damage. If you had a grid-tie system, I will assume you have an interconnect agreement with your utility and are able to continue with NET metering or Sell-Back. You actually have a few choices.
1) Rebuild your grid tie system with a high voltage DC string inverter and add something like an AC coupled Franklin whole house battery/inverter.
2) Rebuild your grid tie system with micoinverters and add something like an AC coupled Franklin whole house battery/inverter.
3) Rebuild your grid tie system with Enphase IQ8 microinverters and add an Enphase battery system.
3) Salvage your old panels and/or add new ones and build a new DC coupled system with a UL1741SA compliant hybrid inverter (with sell-back function) and batteries such as Schneider, Outback or Sol-Ark.

 

[ArtDeco]

Thanks for your quick reply. I haven't followed the solar tech so the only names you mentioned that I recognize are Enphase and outback, so I obviously have a lot of reading to do.
We did salvage 18 panels and the roof rack, and it appears that inverters have come a long way in the last decade. Back then SMC sunny boy was apparently the only inverter that could be used as a grid tie with backup power. I will read up and post to this thread as we go along.

 

[ArtDeco]

Both the Franklin and Enphase systems you mentioned use some type of lithium which after the lithium batteries in my ebike exploded (while just sitting there at 50 or 60 percent SOC neither charging nor discharging) I think i will try to avoid.
I am a bit gun shy ...

I had two strings of 12 250w panels going to two 3500 SMC inverters, so I kind of expect to use two strings of 9 panels and a combiner feeding only one charger / inverter and two 100ah AGM batteries like I had in my campervan (that also burned).

I am in cloudy central Pennsylvania, so only 4 hours or so of full sunlight on my south facing roof, meaning my old system never got close to it's 7 KW rating, often half or less. But it still covered about a third of my electric use with net metering .

The remaining panels should be able to run a few critical loads and keep the batteries charged.

My well and pressure pump is an old 1.5 hp 110 volt unit that will take a lot of power to start, but perhaps an easystart would allow it to run... IDK.

Anyway much to learn, and not much time to learn it ...

 

[BentleyJ]

Soft starter on the well pump is highly recommended, I use a HyperEngineering on our 4 ton AC condenser.
The ebike batteries most likely were li ion, they have very high energy density but are subject to thermal run away and fires. The LiFePO4 (lithium iron phosphate) chemistry in solar storage batteries is much safer and much less subject to overheating and fires. Before choosing lead acid over the far superior LFP type, I would encourage you to take another look.

 

[ArtDeco]

Thanks for that. I haven't looked into battery chemistry at all. My immediate emotional reaction was lithium batteries exactly equal lithium bombs after trying to put the fire out with an extinguisher.

So I just retreated from that technology. But if LiFePO4 is really safe and stable, I know they have much better depth of discharge and vastly more cycles available than any lead acid type.

I am also willing to have the 50 year old well pump replaced with something more efficient and build a concrete block battery safe if that is wise. Somewhere (on this forum?) I saw something about best practices for safe battery handling and will investigate that as well.

Since I am not expecting to run in off grid mode very often or very long (hopefully just days not months) I could get by with some type of lead acid even though they will cost more long term.

I did contact Enphase and have an email from them that I haven't studied yet as well.

 

[houseofancients]

if you're in the us, sol-ark comes to mind.
this class of inverters / chargers are true hybrid, meaning they can take power from either the grid or battery or both.
next to that they can also feed back to the grid.

i, like @BentleyJ would urge you to do some research into LifePO4.

i assume your ebike batteries were the same chem as used in tesla's or powertools, and that chem is much more volatile than LifePO4.

there are a number of nice non DIY batteries, from affordable to really expensive, but with good support from local us resellers and or vendors

 

[ArtDeco]

Yes the ebike batteries were similar chemistry to those used in EVs, and I thought all lithium batteries were similar ... apparently not true.

And the less DIY involved, the better, as far as I am concerned. I even considered a solar generator ( jackery ? Or some such name) just to avoid some wiring . The Sol Ark appears to be bigger than I need or can reliably recharge from my remaining 10 year old panels.

My house is small, 1250 sq ft, and I heat with wood for the 3 or 4 cold months. I am almost 70 years old, so I don't expect to do this again. But then I didn't expect to have to do this now, either.

I have pretty good insurance and many friends who helped out, so up front cost isn't as important as total cost and safety over the next 10 to 15 years (assuming the panels hold up).

 

[houseofancients]

Yes the ebike batteries were similar chemistry to those used in EVs, and I thought all lithium batteries were similar ... apparently not true.

And the less DIY involved, the better, as far as I am concerned. I even considered a solar generator ( jackery ? Or some such name) just to avoid some wiring . The Sol Ark appears to be bigger than I need or can reliably recharge from my remaining 10 year old panels.

My house is small, 1250 sq ft, and I heat with wood for the 3 or 4 cold months. I am almost 70 years old, so I don't expect to do this again. But then I didn't expect to have to do this now, either.

I have pretty good insurance and many friends who helped out, so up front cost isn't as important as total cost and safety over the next 10 to 15 years (assuming the panels hold up).

sol-ark has multiple models, from 5KW up to the in q3 released 15k.....
i would think there might be one that will fit your need

as a personal opinion, stay away from solar generator and such....
lots of fluff for what you get (, low power mppt, too small inverter, too small of a battery and not much more)
in your case, given your insurrance, take a very good look at what they cover ( UL and power codes requirement)
a nice power setup is nice, but you did just find out how important insurance coverage can be if the doodoo hits the fan

 

[Quattrohead]

There are also silicate salt gel batteries that are totally safe and less fussy than LifePO4 - https://watts247.com/product-category/batteries/low-temp-silicate/

 

[ArtDeco]

sol-ark has multiple models, from 5KW up to the in q3 released 15k.....
i would think there might be one that will fit your need

as a personal opinion, stay away from solar generator and such....
lots of fluff for what you get (, low power mppt, too small inverter, too small of a battery and not much more)
in your case, given your insurrance, take a very good look at what they cover ( UL and power codes requirement)
a nice power setup is nice, but you did just find out how important insurance coverage can be if the doodoo hits the fan

Oh Ok. The only sol-ark pages that came up on the first 2 pages of google search results were all 12k or more systems, so I thought that was all they made.

And of course the smelly stuff is still hitting the fan on an almost daily basis with insurance, lawyers, and such people but still better than nothing.

 

[ArtDeco]

There are also silicate salt gel batteries that are totally safe and less fussy than LifePO4 - https://watts247.com/product-category/batteries/low-temp-silicate/

Something else to add to my reading list ! Thanks!
Edit : These look good, so I wonder why I've never heard of them before. Anyone have any experience with them?

 

[ArtDeco]

I am writing back and forth with Enphase about both their microinverters and batteries. This is a very cloudy part of the world and it appears that the microinverters have some advantages here, but that may only be in theory. 9

Or they may be so expensive that they would never pay for themselves, IDK. I haven't found any microinverter based systems in my area, much less an installer that has experience with them.

I expect the panels will need replacing in 10 to 15 years or so, and probably the inverters and batteries as well, I hope I am wrong about that, but an under 10 year payback seems very optimistic .

 

[Quattrohead]

I had a 16x250w panel setup with Enphase micro-inverters in Western MA and you could actually get a few watts out of them on a full moon night, so yes they are very efficient. It was installed in December 2012 and is still providing the estimated output. I can still access it even though I no longer own the house....the buyers could not have cared less that there were panels on the roof :-(

 

[ArtDeco]

At least they didn't take them off as many do. And I recall MA has a rep for cloudy skies, too. That's good too.
Have you heard anything noteworthy about their battery?

 

[ArtDeco]

Apparently the Enphase products are going to be much more expensive than a quality string inverter plus 18 optimizers that are supposed to deal with clouds equally well. In theory, anyway.

Since the panels are already 10 years old, I am told I should try for something with a faster payback even if production suffers , and that would mean a slightly smaller inverter ... 4k vs. 5k for example. It looks like my old inverter (SMC sunnyboys) are back ordered many places. Is there a reasonable substitute that anyone is familiar with?

 

[BentleyJ]

Fronius Primo 3.8 or 5.0 may be of interest. Our 11 year old Solar City system has the Fronius IG Plus 3.0, so far no problems other than 1 of the 2 cooling fans started making noise so I replaced it recently. Since Tesla now owns the lease I probably should have contacted them for the repair but all things considered it wasn't worth the trouble dealing with Tesla just to save $40 and about 30 min.