The rumours of my demise have been greatly exaggerated

[SIR VEYOR]

If you think of trying a NG genny, plumb a big bottle/tank in-line somewhere. Big hit to fill first time, but then you have a reserve in place. Should be able to let it free flow and auto shut off the intake on a pressure drop, or plumb it in parallel and work the taps to change it over.

Just don’t make it obvious what you’ve done.

 

[CanCuba]

I've had a battery backed PV system for about 14 years. They cost a lot more back then and our rates haven't gone up a whole lot (yet), making the breakeven point pretty bad. I'm not sure of hitting it even in 20 or 25 years. Since the initial cost I've had to replace the charge controller and batteries making the payback even worse. On the flip side, the convenience is of huge value. It's a mostly whole-house UPS, and when the power goes out we don't know it until a neighbor calls to ask if our power is out. I'm disappointed with the slow payback, but the UPS function makes it all worthwhile.

If you've had to replace the batteries, that's a huge setback in terms of break-even. They're far and away the most expensive part of the these systems now. Have you had to replace any panels due to failure or storm damage?

Yeah, the UPS part would be very convenient. I guess it's not all about money.

 

[tigerwillow1]

They're far and away the most expensive part of the these systems now. Have you had to replace any panels due to failure or storm damage?

At the time my system went in, the panels were the most expensive part, plus I had a small battery 5 kWh. Since then the price of panels has come way down, and batteries up. Now I have 21 kWh of LiFePO4. No panel failures or damage, in spite of a bunch of hailstorms, including one that was close to golf-ball sized hail.

 

[Mike A.]

Now I have 21 kWh of LiFePO4...

I've been thinking about building a bank for myself. How many physical batteries does that represent? Seems like LiFePO4 batteries have come way down lately. But I'm looking at them for boat electronics/trolling motor use not hooked together. I bought a 100ah for < $200 a while back and that was kind of a better one with high-amp draw, Bluetooth BMS. Probably can get basic no-names for $150-ish.

 

[tigerwillow1]

I have three 52 volt batteries, with 52 volts being 16 cells in series. If you're ever connecting 12 volt batteries in series, make sure they can do that, because some of the 12 volt BMSs won't tolerate the higher voltage. My batteries use 135 amp cells, for right at 7 kWh capacity. They were in kit form from Seplos at an introductory price. Seplos still sells kits but no longer includes the cells, and they don't target the USA market any more. One of the popular brands with solar installers is SimpliPhi SimpliPhi Batteries - Inverter Supply, and with DIYers, EG4 All Products - Batteries - Signature Solar . These are all targeted for PV system storage, although there is a 12 volt 5 kWh (400 Ah) version of the EG4 battery that could be attractive to tinkerers with its front panel display and remote monitor capability. If you want or need that capacity, it might be less hassle than paralleling smaller batteries and wondering if they're balanced. I never got into the bluetooth connectivity. As with cameras, I prefer a wired connection

 

[Mike A.]

Yes, I should have specified 12v above. Looks a lot different for the higher voltage batteries. Not as much of a commodity. I'll have to study up some. I'm aware of the limits to connecting multiple batteries. A lot of 24v and 36v in the boat world also. Bluetooth is nice to have for my purposes to easily track charge level and remaining power when on the water. There are shunts that can be wired in but more wires and more 'stuff' in a small space, And from what I've seen having it tends to be an indication of a relatively better quality BMS used at that level of battery.