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Solar production getting worse in Bay Area, California

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Size is about 30kw. The panels are all south, north and west. The north ones will get very little in the winter I expect. But, I hope I oversized enough that during the great months of like april to July, I can bank lots of energy for the winter use, since I am 99% electric with a big house.

I produced 4.8MKh in June.
Would love to see your panel layout if you can please.
 
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Hello fellow bay area,

My 4kW system (installed in January 2021) production peaked in May and then got worse and worse over this summer.
I wonder if it is due to wild fire smoke or my panels just need cleaning.
Please share your data point, thanks!

...
Others have mentioned some good points. We are not far apart in location so your daylight hour length are very close. Mine is 14:40 hours long on 20 June and 9:40 hours on Dec 20th, shortest day; five hours difference in daylight and sun arc changes as well, highest in June and lowest in Dec. day length changes the slowest around the 20th of each of those peaks, meaning it takes many days to gain or lose 1 min and changes the fastest around Mar 20 and Sep 20th. Easy to find out if you subscribe to your local newspaper with weather info.

My system is essentially the same size as yours. I am in my 10th year of operation and made a yearly and monthly chart. Weather is the greatest changer of production. Monterey has lots of fog especially where my house is. Your short time on line is too short to make heads or tales of it. I bet you have fog issues as well.
As an example my first year production for May was 717kWh and was the best month for the year. Year two, 2013 May was also the best for the year with 711kWh. Same for year 3, 2014 with 682kWh and best for that year as well. But, that year 3 May while the best for the year was only 4th best May of 10 Mays. 2019 May was number 3 with 691kWh and also the best month for 2019. So, it is all over the place, more or less. If you want I can post my chart and rankings.

In 2017, July was the best month for the year with 661kWh and also the best July of 10 Julys on the chart. In 2015, Aug has that honor, best for year and best for all the months.

As you can see from this short synopsis there is no real pattern of degradation , just weather related.
 
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Our production in central MA is definitely down this year, mostly due to the absurd amount of rain we've had this summer.

These are our readings for the past 5 years, starting 2017 (1st full year of install) - all data is Jan 1st to Sep 3rd each year

2017 - 5177 kWh
2018 - 5166 kWh
2019 - 5452 kWh
2020 - 5403 kWh
2021 - 4603 kWh
Don’t forget all of the extra “cloud” cover in the form of the smoke crossing the country from the PNW fires.
 
I am in the Bay Area and my system is clearly degrading. 2020 was less than 74% of 2013. These are 240W polysilicon panels on Enphase M250 micros.

Solar Production Charts_r.jpg
 
bumping this, but after the "rain" we got here in the bay area last night, my panels peak production went up by 1kW from the previous day. I have 8.16kW system installed on 8/24/21, first week I has hitting peak of 6.1-6.2kW, over the next month and so, peak production started going down, I saw the panels had some dust on, but thought we are going into fall, so probably that is why. However, today my system start peaking 6.1-6.0kW and panels looks clean.
 
bumping this, but after the "rain" we got here in the bay area last night, my panels peak production went up by 1kW from the previous day. I have 8.16kW system installed on 8/24/21, first week I has hitting peak of 6.1-6.2kW, over the next month and so, peak production started going down, I saw the panels had some dust on, but thought we are going into fall, so probably that is why. However, today my system start peaking 6.1-6.0kW and panels looks clean.
Sounds good. But at least by me, yesterday was partially cloudy and that means you get cloud edge effect that can temporarily boost the peak production numbers as the sunshine goes through the water molecules at the edge of a cloud. As I understand it, these edges act as lenses concentrating the photons. I know we see some of our highest peaks on partially cloudy days like yesterday.

I am interested to see what we get today which looks to have fewer clouds.
 
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So this thread brings up a question I have on the powerwall setting for the winter. I’m running my house off the Powerwalls from 4 to 9 peak, should I lower my reserve and just keep my setting on time based and if it gets to the reserve because of not enough sun let it then pull from the grid until the Powerwalls charges to 100%. Looks like for the next 7 days or so it will be cloudy and raining.
 
So this thread brings up a question I have on the powerwall setting for the winter. I’m running my house off the Powerwalls from 4 to 9 peak, should I lower my reserve and just keep my setting on time based and if it gets to the reserve because of not enough sun let it then pull from the grid until the Powerwalls charges to 100%. Looks like for the next 7 days or so it will be cloudy and raining.
I have had my reserve at 15%. But, yep, with the rain coming, do not expect I can fully recharge the PW's, so the first time this happens, guess I will increase the reserve
 
So this thread brings up a question I have on the powerwall setting for the winter. I’m running my house off the Powerwalls from 4 to 9 peak, should I lower my reserve and just keep my setting on time based and if it gets to the reserve because of not enough sun let it then pull from the grid until the Powerwalls charges to 100%. Looks like for the next 7 days or so it will be cloudy and raining.


IMO, this is the toughest season for Solar + Powerwall unless you're h2ofun with a monstrously oversized solar array.

The rain and high winds present what is supposed to be the worst impact to grid reliability. For example, the 0.25 inches of rain we saw on Sunday knocked out power to like 30,000 homes. 3 people at my work alone had no power for most of yesterday. Can you imagine any other grid in the USA that becomes unstable with 0.25 inches of rain?

So if you have Powerwalls with the intention of having some backup during an outage, you will want to set your reserve to a rather high level.

That is why the ideal situation is to be able to top off your Powerwalls a bit with grid energy from like 3am to 6am. Maybe not to 100%, but just enough so that the next day's muted solar production can fill up the remainder. This way you make sure you never tap into shoulder or peak rates. I really wish Tesla would allow this functionality when the weather has expected rain/clouds in the forecast.
 
IMO, this is the toughest season for Solar + Powerwall unless you're h2ofun with a monstrously oversized solar array.

The rain and high winds present what is supposed to be the worst impact to grid reliability. For example, the 0.25 inches of rain we saw on Sunday knocked out power to like 30,000 homes. 3 people at my work alone had no power for most of yesterday. Can you imagine any other grid in the USA that becomes unstable with 0.25 inches of rain?

So if you have Powerwalls with the intention of having some backup during an outage, you will want to set your reserve to a rather high level.

That is why the ideal situation is to be able to top off your Powerwalls a bit with grid energy from like 3am to 6am. Maybe not to 100%, but just enough so that the next day's muted solar production can fill up the remainder. This way you make sure you never tap into shoulder or peak rates. I really wish Tesla would allow this functionality when the weather has expected rain/clouds in the forecast.
I would say California is the issue for we cannot keep power on, but lets force more things electric