In defense of Neil, this is a capital addition to his property, so you cannot account for it as dead money. I’m not saying he’ll get dollar for dollar, but this system adds value to his property that will be realized when it is sold. Also, he’s reducing the load on the Texas grid and reducing greenhouse gasses.
Some questions for Neil:
I believe your home is a relatively new build, but have you had its air-tightness checked recently? It might be worth having that done so as to close up any major leaks that inflate your electric usage. Further, having it checked for major heat sinks might be worthwhile so they can be remediated and further reduce your usage.
Are you allowed to use the battery system when the grid is down? I remember Waldo saying that Texas requires your system to be off when the grid is down, whereas most other states allow you to have an automatic cutoff to isolate your system from the grid if it’s down.
It looks like you’re designing the system to power the whole house during outages. Alternatively, you can install a smart breaker box that allows you to shut off power to non-essential circuits so that, for example, you are only air conditioning certain areas of the house when on battery, and only powering certain appliances. The Span Smart Panel does this, is controlled by an app on your phone and includes an automatic cutoff from the grid. You might be able to get away with one battery in those circumstances.
As I recall, here are the possible scenarios, at least when I got my system in 2017:
You can get solar panels without a battery system, and sell excess power back to the grid. Your house loses power in the event of a utility outage.
You can get solar panels with a battery system, but cannot sell excess power back to the grid. Your house runs off of the batteries in the event of a utility outage.
You cannot get a permit for a battery system without having solar panels.
Not sure if all of that is still the case, but I think it is.
I don’t know if this methodology is correct, but 24,795 kWh / 8,760 hours mean you’re averaging 2.83 kWh per hour. I know I’m somehow doubling up on “hour”, hence my equivocation. This seems too simple.
Solar systems are sized in kW (not kWh), which is just the raw aggregate generating capacity of all the solar panels. I have 43 panels which are each rated for up to 320W, so my system size is 13.76kW.
As far as how that directly translates into kWh, it gets pretty murky for a number of reasons. What I can say is that since June 2017 my daily average for solar production is about 48kWh, which works out to about 17,500kWh/year. YMMV.
Right…this is what I’m asking…if a system is 15 kW, how many kWh can that produce, at what frequency. I know there’s a formula for figuring that out, and that depends greatly on where you live and how much raw sunshine you get at what angles. I might need as much as 100 kWh/day during August, so just trying to understand how many panels I’d need. I think a lot more than 43 panels, and I have a two story house, which halves my roof area relative to square footage.
Not getting into the math, but you don’t need to have a system that can handle the worst days; that’s what the grid connection is for. You build the system to handle the rest of the year, e.g. Sept to May.
If I want to get off the grid, I do. And even if I’m on the grid, every kWh I don’t get from my solar system lengthens the time it takes to break even on the initial investment. I’m not arguing against solar panel, I actually do want to get into the math.
you have to look at the panels and battery separate. The batteries aren’t necessary for the solar system, and replace a generator. They do smooth out the system, but essentially instead of spending $15000 on a generator we’re spending $24000 on batteries. Maybe not the smartest deal, but I don’t have anyplace to put a generator.
We’ve been told that when the grid goes down, the system will be taken off the grid. The batteries will run the house for 13 hours, but the system will let us choose critical loads to increase that. More importantly, power produced by the panels will divert to the batteries. I asked about this specifically.
3). Solar only produces power during the day. With three of us home most of the time, our highest usage is in the summer, but with solar, most of our purchased electricity will be in the winter at night. I can either get credits by overproducing during the day, or find plans that offer special deals on nighttime power. To answer part of HH’s question, when you use the power becomes important, so you can’t completely translate annual usage into system requirements.
Houston doesn’t have rebates, so the cost of an 80% system, without considering the batteries, will be about $40,000, less the 26% tax credit, so about $30,000. It’s estimated that of our total annual electricity cost of $3500, we’ll save about $2600. That’s a return of bit more than 8%. I’m sure we’ll have additional insurance and maintenance costs.
Obviously I don’t know the actual numbers, but it will come down to the additional cost to build a system to handle the worst summer months, vs. building a system to handle the non-peak months and paying the cost to buy juice from the grid to top up when needed.
For example, a Tesla Powerwall battery cost about $12,000. If you can get away with one for 10 months of the year but need two during the peak months, you can go a lifetime paying the top-up cost from the grid before you have spent more than the cost of the additional battery.
Look at say your March vs. August electric bills, and multiply the difference by 2 months and, say, 25 years (which I believe is the advertised life of these systems). Even if the difference is $100/month, over 25 years that’s still only $5,000, in increments of $200/year. Hard to justify an extra battery, or perhaps even just additional panel area, simply to avoid that bill.
But if you want off the grid completely and forever, you’re going to have to invest upfront in the infrastructure to do it, or you’re going to have to Apollo 13 your way through July and August.
Someone above asked about the F-150 Lightning fleet model. Here’s a review of the “Pro” model, which is ridiculous value for $40k (less $7,500 tax credit).
I read that many towns/communities (likely in CA) are outlawing gas-powered equipment and generators. This thing is ideal for a contractor in such circumstances because you can run bench saws and probably a cement mixer off this thing - it has a 240V outlet - and there are tons of 110V outlets to have spare batteries charging for your handheld equipment.
The only downside - other than about a 2-year waiting list if you don’t have an order placed already - is the 150V charging infrastructure. It has a huge battery (98kWh) and, with only 230 miles of range, by the time your work day is done I’m not sure you’re going to be able to be back at full charge overnight even on a Level 2 charger.
You have the option of hitting a DC fast-charger to start the day, of course, but that’s where the 150V charging limit is going to hurt. They need to give it 350V charging architecture so that the battery can be topped off while the guys grab coffee/breakfast. A food truck at every fast-charger now sounds like an essential element of the EV experience.
The rolling production pause of EV’s from VAG is over and they are starting production across multiple lines again. With the fight in Ukraine shifting to the eastern regions, the wiring harness production that supplies most of the German and French automakers has started up again and the production pause allowed them to restock depleted chips. Like other EV makers, VAG is focusing restarted production on their highest ($$) yield vehicles. Specifically, those that were designed from the ground up as an EV rather than a retrofit of an ICE-bodied vehicle since they yield lower revenue margins. For me personally, this means the estimate for delivery is now the first week in August.
