Newbie planning a large system. Advice? Criticism? Thoughts?

[trenshaw]

So to start I live in Georgia and my utility is Georgia Power. I almost installed a system a few years ago, but I was not able to get into the original 5000 net metering contracts before they switched to "instantaneous net metering". Because of that we decided not to proceed because I couldn't see the value in solar plus instantaneous net metering without also installing batteries. Fast forward to this year and we now have an EV, we are on a TOU plan, and Georgia Power has just raised their rates resulting in our highest bill ever at $482.92 for 2854kWh (396 on peak, 1210 off peak, 1248 super off peak). We are also projected to owe about $8000 in taxes this year, so I figured I start planning a new system, then that tax money could go toward something useful instead. We have a large house, 4171 square feet with a 400 amp service and two 200 amp panels. Our main air conditioning system uses both panels, with the condenser on one and the air handler on the other, so we really need to power both panels. Right now my plan is in get the inverters (2 EG4 18KPV) and batteries (4 EG4LL-S 48V) installed this year and add solar next year, which will spread out the costs and make it a little easier for us. With just the inverters and batteries we can start peak shaving and hopefully eliminate all on peak usage, which is about 10x more expensive than super off peak. I think I have a decent plan but there are some gaps that I need to fill in, namely how to connect the batteries to the inverters since I don't plan on a normal rack.

This is the meter panel on the outside of the house.



This is the wall inside the garage behind the outside service panel, and where I plan to install the system. If I disassemble this wall it should be easy to get access to the feeder lines to the two 200 amp panels and redirect them to the inverters, plus install new feeder lines from the outside service panel to the inverters.



This is a sketchup rendering of what I plan to install. You can see the two inverters on the wall, with 6x6 wire troughs horizontal below them and vertical between them. You can also see the batteries along the ceiling. Right now the plan is to support them with 4x4s on wither end and a 4x8 (2 2x8's plus plywood) header across. If I need to add another post in the middle I'll be fine with that too. The batteries will sit on angle iron runners for support, though I didn't model that. This rendering has way more batteries then we'll have at the beginning, but I figure we can add on over time to fill it out. I briefly thought about EG4's indoor wall mount battery because it would fit so well here, but since the two 200 amp panels are not utilized equally, I thought it would be a little lopsided and we wouldn't get the best value out of them.



The part that I haven't figured out yet is how to get the batteries wired to the inverters. I was thinking I'd add another wire trough either horizontal along the wall just under the batteries or on the back side of the header. I'd like to put a bus bar in it but I'm having a hard time finding a source for actual bus bars that long outside the ones bundled with server racks.

Also is there free or affordable software to draw all of this up for the permitting process? I plan to install everything myself but have a licensed electrician come in to to the final "hook everything up".

Any ideas, thoughts, warnings, criticisms would be much appreciated.

 

[ConnerLabs]

Heavy batteries at ceiling height? How are they getting up there and down for maintenance?

 

[TechRider]

For the batteries, you want them all connected to both inverters. (Especially if you run them in parallel.) You'd just wire the inverters to the same bus as the batteries. You could do something like run 2 large wires (4/0) down to a smaller bus and hook the inverters to that. The rule of thumb is to have all the batteries have the same length of wire/bus. There are a few threads discussing it here.

 

[Bananaman321]

Heat is the number one enemy to these batteries it is recommended to keep them closer to the ground and also the energy density of a wall mount batteries would be preferred in your installation

 

[Bananaman321]

It looks as though you have room for three of those wall mount batteries 43kwh they also make outdoor versions but it is not recommended to have them in direct sunlight.

 

[wpns]

Have you done a sanity check on your loads, and done a power survey? 18Kpv is good for about 50 amps, one for each 200A breaker box _might_ work, as many people have much less load than they think they do, but without a survey you'll only know if the inverters trip out that you undersized the system.

Likewise, the batteries you've chosen are good for 5KW each, so they'll trip out before the inverters do.

Get an Emporia Vue or equivalent and do a power survey, then you'll know your peak power (KW), daily energy requirements (KWHR), and you can select inverters, batteries, etc.

If you are putting them in a garage, I'd recommend the PowerPro WallMount batteries, and if you got the Outdoor model you could have room for expansion on the outside of the wall.

 

[trenshaw]

Wow you guys are awesome, lots of replies very quickly.

As for the difficulty in maintenance, I'm much more worried about using the space efficiently than I am how difficult it will be to get them up there and down. Worst case I can rent one of those manual lifts, but I have enough help that I can get them up and down just fine. With all the bikes, toys, and tools we have, space is already at a premium. I just bought a 6" jointer this past weekend and don't know where I'm going to put it. If budget was no concern I'd get a shed out back to keep all this in.

I do like the wall mount batteries, and like I said I considered them. However the price per kWh is higher, and in the diagram I have room for 75kWh, plus if I wanted we could do another section along the top of the wall to the right.

As for the heat, I don't think I'll need to worry about that. This is a built-in garage, so it is under conditioned space, and the entire exterior wall with the garage doors never get direct sunlight, so it stays pretty comfortable out there. It's definitely within the operating temps listed for the batteries.

As for the inverters, I have been considering the 18Kpv and the Sol-Ark 15K because they advertise 200 amp pass through. The wiring diagram in the manual of the Sol-Ark has the feeder lines from the meter go straight into the inverter, and the load for the entire house coming out. It is my understanding that anything we draw over the capability of the inverter will come from the grid. Please advise if I misunderstand that.

I have not checked peak loads yet. I have a simple logging power meter and I have checked total daily usage for some circuits, but not peak demand. I would assume we go over 50 amps per panel occasionally, say if we are charging the car at 48 amps and the AC kicks on, both the condenser and air handler are on 50 amp breakers so I assume the start up surge from both of them is more than 30 amps each. We also have a well pump for irrigation, so the right combination of things going at the same time would probably do it.

Room for battery expansion outside is also not doable. The outside of that wall is either doors or service entrance panel.

I've read some of those threads on the same length of wire for each battery and it's still unclear to me exactly what people mean. Is it the same length of wire from the battery to the bus or the same length of the path through the wire, through the bus, to the inverter, because as far as I can tell the pre-bundled server racks of batteries only meet one of those descriptions.