I am putting a new screened in porch on the north side of the house. Part of the roof is pitch @ 32 Degrees and facing south so it will be ready for solar early next year. I have been considering solar / battery storage ( aka the Powerwall approach ) as apparently you have already done so. Like you I like to have more than one option for insuring I have electric power. Georgia Power does have large solar farms and lots of Nukes, so the generation side is secure. It's getting the power to my house is the real concern.
If you would like to share ...
what was the cost of your Tesla Powerwall system? what is the capacity in AHrs or KWHrs. Did you do the install yourself, or if not who did you contract with.
What solar capacity do you have and what was the overall cost of the installation?
SAVANNAH, GA 31411-2508
I installed a ground based solar solution because I didn't want to get on the roof, I did the solar solution myself and installed 18 panels, all of them 360w. There are 2 rows of 9 and I put sonotubes in the ground to support the wooden base foundation that the frame is installed onto. That's optional. The frame does tilt but it's completely manual and it is a two person job to do it safely. After shipping, the ground frame kit for 18 panels ended up being $1080. It's similar to installing a suspended ceiling in the number or things/parts/bars/etc... You've got end caps, rails, fastening objects, inverters and the necessary monitoring. My house and property is fully home control automated right down to the NG fire pits, torches, etc. Alexa can start my grills. So, I want to know exactly what is coming from the solar which the Powerwalls appreciates and meters too so they know how to operate. They make 410w panels now btw, but those are more than I want to spend. My plan is to stay net zero. I put in the genset, an air cooled 22kW in 2014. But solar incentives from the Federal Govt are getting slashed EOY so I decided to use that excuse to push ahead. I've always wanted solar and a nanny. I wasn't sure I was ever going to get either but life rewards you now and then. My utility provider offers no real incentives and does what it can to punish alternative energy proponents so the concept of selling my energy was not in scope. So, I decided that if I had extra energy, to store it. And that is where the Tesla Powerwalls came into the plan. Buying a Tesla Powerwall has the same experience as buying the car. You can price it online, but if you call, the price is actually lower. Remember that if you buy the car, build it online, but don't buy it online. I have EV's btw, and I'll explain the one error in that plan that I have to adjust for next spring. In any case. I installed the genset myself, and the solar myself but my integrator for the Powerwall forced my hand. The suppliers who would allow me self-install either made up for it in the price or availability was too far out in the future. You need to find an integrator who orders Powerwalls under fake customer names who magically back out after the Powerwalls come in .... a couple in my area do that. In any case, I paid for the Tesla component installation, see below.
Solar panels, monocrystalline 360w x 18 delivered was $4100. These are dropping fairly fast in cost. They come crated, so check with your HOA on burning wood.
Ground installation kit as mentioned above, $1080 delivered.
2 Powerwall 2's were $7250/ea. They are 13.5kWh units each.
Labor for the Powerwalls was $2400! It should have been half of that in my opinion. It took them less than a day.
The Backup Gateway 2, with the optional panelboard and the extra metering was a grand. They will tell you it's $2200, that's MSRP. Don't pay MSRP.
I wired for 6 Powerwalls, that's what the calculations came out for but I only installed 2 because of the genset is a variable to consider.
The genset will not charge the Powerwalls, the Powerwalls are before the ATS.
I operate in the self consumption mode, so I run the house off of the solar during the day and the solar charges the Powerwalls. The Powerwalls are set to reserve 40% for backup so they will never discharge below that. You configure that value. So, if we get below 40%, the house will take grid power. It won't charge the Powerwalls unless the grid is providing cheaper TOU power. Another item you control. The Powerwalls charge at a rate of 1.7kW's each. All these things are customizatable. You can run in backup mode if you don't have solar. Or you can run in backup mode if you have solar. In this mode, the Powerwalls will maintain 100% charge, will take that charging power from Solar or the grid. And the Powerwalls will standby for a grid outage. I am not in that mode.
Since I have the genset, I'm not so concerned about sustained grid outage run time. But, where I went wrong as I mentioned above is with my EV's. I calculated everything with summer consumption numbers. I didn't calculate what my EV energy consumption in the winter is. My primary EV has active battery management cooling so it's winter power usage to warm the battery AND keep me toasty is much more than the summer. The air conditioning hit on an EV is negligible, almost not worth measuing. But heating the cabin for the carbon based lifeforms is where you take the big hit. The hit to warm the battery is much less. So, my point is as I babble is that when I get home in the summer, the charge time is between 1 and 2 hours each night. In the winter, the same driving, is going to be between 3 and 4 hours.
What's next? Adding more solar, but I'm going to wait to see if the government renews the legislated perks that expire EOY. I believe they will, but not sure. If I didn't have the genset, I'd run more Powerwalls, but the genset is there. It's not been as reliable as it should be and much less reliable than the average 22kW. The numbers above are exact. I did get a $1000 cash rebate from a program called Focus on Energy. I received nothing else, beyond the tax credits on the Federal side that everyone gets which are not yet realized as this was all completed end of summer. My utility does not give rebates. My state does not give rebates. I paid cash, cashed out comp time from work. I do a lot of overtime. The only numbers I did not include because I can't honestly give you exact numbers is for the wire to the Solar farm which is 200 feet east of my house. I had a lot of wire left over from my generator project and 3 of my best friends are electricians (one lives 3 doors down) and I got the 'extra' wire 'left' over from jobs and 'end' of spools and other discounts that would make a great story line for Miami Vice. Also, I bought optional and supplemental surge suppressors to protect the panels and other goodies in different directions. I need to find that invoice.