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17kW System = 98.4 kWh Production (5.79kWh/kW of Panels)
- Thread starter mstgkillr
- Start date
darhall993
Member
Yep I‘ve done several upgrades in panels and from 7.6 to 11.4 inverter, when it’s cool in spring I can clip a fair bit, but once summer comes along the production degrades as it in the 90’s alot here so I made the decision to add a few more panels (went from 10.8 to 13.8 kW) to hit 1.2 ratio.
I have the system oversized for peak usage of AC in the summer, we rarely use more than 70kWh/day on the hottest days of summer. This system should do 85-90 kWh or more during summer on nice days. I did the last panel additions in September so I’ve not seen spring or summer with the current setup
darhall993
Member
I'm in DFW area, 42 panels I think (don't remember), but it's a 16.2kWp system.. Had my best day the other day, almost hit 100.. Had the system since Aug-20.
Also included my lowest ever when we had that terrible winter storm here in Texas in Feb that shutdown the grid.. My Solar did nothing to contribute back to the grid those few days.. Panels covered in snow, cloud cover, and the grid kept coming and going.. Renewable energy did jack for us during that terrible week.
Also included my lowest ever when we had that terrible winter storm here in Texas in Feb that shutdown the grid.. My Solar did nothing to contribute back to the grid those few days.. Panels covered in snow, cloud cover, and the grid kept coming and going.. Renewable energy did jack for us during that terrible week.
Get a roof rake and clear off some panels. We received over 2 feet of snow on 3/14/21. The next day, I cleared the snow off a quarter of our panels with our 21' roof rake. An hour later, the snow slid off another third of our panels in a mini-avalanche. Our system generated over 45 kWh that day since the sun was out.
Even when the sun doesn't come out, our system is able to generate 2 to 3 kW throughout the day. On 3/21, we had another 8" of snow. I cleared off a few panels and even with all the clouds, our system was able to generate 17 kW over a 5 hour period, which was more than enough to power the house and charge the Powerwalls back up slightly.
Would you buy it from me when I never use it again? Lol.. We don't get cold and snow here like that, what happened in Feb is unheard of in the last 100yrs in Texas..
I've been here for 8 years now, we've had maybe 1" total of snow the whole time I've been here. I'm from the north, and the north can keep the snow and cold.
Our 21' snow rake cost like $30 and has already paid for itself. We just ordered a 24' one that cost more but will allow us to clear nearly all panels.
If you already have Powerwalls then $30 is a pretty small investment to keep your solar system up and running during a multi-day grid outage. If you don't have Powerwalls, then solar is pretty worthless when the grid is down...but I don't know why anyone wouldn't put in at least one Powerwall to keep their solar system operating in an emergency.
SoCalSolarRoof
Member
In California, I've only had 2 power outages that were more than 5 minutes in the last 10 years. The last one was summer 2020, and it was at 7pm, for 90 minutes, so I wouldn't have been producing anyways.
With that track record, it's hard to justify the cost of the battery.
Same here.. I can count on my hands how many power outages we've had since living here for 8 years.. There would never be any ROI for me with Powerwalls, and the batteries would go bad before that ever happens.. Power is so cheap here too, it was hard to even justify Solar at a 10yr ROI even after the tax credit, but I sucked the up front cost and paid it outright, mainly just to have a consistent bill and hedge my bets. Power is around 10.5 cents/kWh fixed rate, but my power does company does give 1:1 credits which is nice.
Would it have been nice to have it during that storm? Of course, but 3 days of power going off/on every 30 minutes vs another 25K+ in power-wall costs (need 4 for our power requirements, we have a very large home). The neighbor across the road had it and they were laughing at us, but they spent almost 100K on their solar/battery system, which is just nuts to me.. If anything I'll just get a whole home generator for a fraction of the cost.
It kind of depends on how one views the word "justify" - it looks like my 16.32 + 3 PWs in SoCal will allow me to be off grid from about a week ago until November, straight through. During that time, it will be interesting to see what credit I get for power fed to the grid during that time.
Without going into detail, from a pure "how much does it cost" angle my system is oversized - like buckweet1980, there have not been many extended outages.
But over twenty years the extra cost per month is like $100 or $150 vs. a system which is perfectly sized. That $100 or $150 is, of course, another $20k.
Maybe I am wrong, but since power is a monthly cost, I look at the system as a monthly cost. I probably blow $100 a month on coffee. To have 3 PW's for the cost of a month of overpriced Starbucks does not really seem foolish.
I mean, depending on how one defines "foolish."
I might add, this is not the same as comparing, say, one cable company to another or Dish network to ATT. In that case both are simply a service, there is no satisfaction in selecting one cable/internet utility over another. But I find the difference between having my own energy system v. LADWP to be very, very much different.
Maybe we all justify our own spending. But if find grid independence to be so incredibly cool that it far exceeds whatever coolness there is in someone preparing coffee or food for me. Ciao gang.
For me, playing with the technology is fun. Spending my kids inheritance is even more funIt kind of depends on how one views the word "justify" - it looks like my 16.32 + 3 PWs in SoCal will allow me to be off grid from about a week ago until November, straight through. During that time, it will be interesting to see what credit I get for power fed to the grid during that time.
Without going into detail, from a pure "how much does it cost" angle my system is oversized - like buckweet1980, there have not been many extended outages.
But over twenty years the extra cost per month is like $100 or $150 vs. a system which is perfectly sized. That $100 or $150 is, of course, another $20k.
Maybe I am wrong, but since power is a monthly cost, I look at the system as a monthly cost. I probably blow $100 a month on coffee. To have 3 PW's for the cost of a month of overpriced Starbucks does not really seem foolish.
I mean, depending on how one defines "foolish."
I might add, this is not the same as comparing, say, one cable company to another or Dish network to ATT. In that case both are simply a service, there is no satisfaction in selecting one cable/internet utility over another. But I find the difference between having my own energy system v. LADWP to be very, very much different.
Maybe we all justify our own spending. But if find grid independence to be so incredibly cool that it far exceeds whatever coolness there is in someone preparing coffee or food for me. Ciao gang.
I'm on PG&E and the offset of not using $0.49 / kwh energy ever when I'm running the AC in the central valley in the summer will net over $7 to $12 / day through most of the summer over no solar alone....and that doesn't include the fact that I'm sending every kwh produced from 3 to midnight (part peak and peak) back to the grid allowing me to use 2.5 times as many kwhs for the same price.
SoCalSolarRoof
Member
Totally fair points. For our family, using ~7,000kWh/yr and generating ~10,000kWh/yr, I couldn't make the math work for 2x powerwalls, which is what we were told we'd need to run the AC. Every case is different. Glad it made sense for you!
And it's not a 100% offset in ROI time. But it's really significant that it's not that much further out than the ROI payback on solar alone. But that relatively small difference is the actual cost for me having a power outage backup.
Also, I've had 8 power outages since December. 3 of those were at night where neighbors got to drive by or look out there windows and see all my lights still on. I admit I even turned on outside lights just to show off
Another way to look at it. For every kwh I could time shift from peak to off peak, I save a 30 cents (58 (peak) - 18 cents (off peak)).
The estimated charge life cycle of full 0 to 100% charges (worst case scenario) is 3100. Assuming a high level of degradation resulting in only 80% of the 40KW of 8m 3 powerwalls over it's lifetime, this gives me:
3100*40*0.8*0.3(cents) = $29760 in peak time offset over the estimated life of the product. My cost for all 3 powerwalls after the tax credit is $15170. The price has gone up twice since I ordered last year so it's not quite as attractive now as it was then.
The estimated charge life cycle of full 0 to 100% charges (worst case scenario) is 3100. Assuming a high level of degradation resulting in only 80% of the 40KW of 8m 3 powerwalls over it's lifetime, this gives me:
3100*40*0.8*0.3(cents) = $29760 in peak time offset over the estimated life of the product. My cost for all 3 powerwalls after the tax credit is $15170. The price has gone up twice since I ordered last year so it's not quite as attractive now as it was then.
I am assuming without running numbers that if I can use my batteries 100% during ev2-a peak, and send back solar from 3pm to dark, that I would end up far ahead overall. I just want to be able to heat and cool my house and have a zero, or even I over produced, True up. This is why I am thinking of putting more panels on. It is all a game. I sure know that PGE rates or processes will not favor the consumer going forward, in Calif. So the closer I can get to being off grid, the less their changes impact me
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