Expected monthly generation in San Diego (SDGE area)

[Kaya]

I recently have solar installed in San Diego (4.8W DC (16 - 300W panels), 4.26W AC) and received PTO on November 1st, 2017.

I have a few questions to experts on expected power generation in San Diego area.

1) For the first 21 days of the month, I generated around 306kWhr (5 of my panels are facing south, 11 facing west, tricky roof). I will probably have around 400-450k kWhr generated by the end of the month. Do you think this is a reasonable amount for November for a system of this size? I have built in inverters and can see west facing produced around %25 less than the south facing panels.

2) I was expecting on average 5kWhr per 1W DC for the whole year in sunny San Diego. Is this a realistics expectation considering longer summer days? Do you have any generation data you can share over the course of a year in table format on a monthly basis? I am trying to figure out the delta between summer and winter months.

Thanks!

[sensij]

Team San Diego at PVOutput has lots of historical data of real systems in the area. This year, November has been kind of cloudy, so production is lower than some other years.

5 kWh per kW is probably optimistic for a daily average, especially with so many panels west facing. Here is data from a 4.8 kW system with SW facing panels in Carlsbad, showing 4.88 kWh / kW average daily production in 2015, and 4.79 kWh / kW in 2016. That system has produced 360 kWh so far month to date, so your system with less optimal orientation looks about right.

In any case, that daily average will vary with the seasons and weather, probably over 6.0 kWh / kW in the summer and less than 3.0 kWh / kW in winter.

[Kaya]

Thanks sensij, that site has very detailed info, I will register and feed my generation on PVoutput. I wish I could place more panels facing south but I did not have any roof space.

It is interesting to see that spring generation is higher than summer generation for this year for most systems in Southern California. I was reading cooler/sunnier weather is bettter for panel performance (compared to hotter/sunnier) -even though summer has longer hours. In winter shortest days provides roughly 10 hour, in summer on 6/21 we get 14 hours and 40 mins in SD.

I was grandfathered into 5 year plan DR-SES with ToU, may be west facing panels will be more helpful after 5 year when I switch to new ToU rates. Although I may generate more than I consume at the end of the true-up period, which will make ToU irrelevant, is that true?

[J.P.M.]

Thanks sensij, that site has very detailed info, I will register and feed my generation on PVoutput. I wish I could place more panels facing south but I did not have any roof space.

It is interesting to see that spring generation is higher than summer generation for this year for most systems in Southern California. I was reading cooler/sunnier weather is bettter for panel performance (compared to hotter/sunnier) -even though summer has longer hours. In winter shortest days provides roughly 10 hour, in summer on 6/21 we get 14 hours and 40 mins in SD.

I was grandfathered into 5 year plan DR-SES with ToU, may be west facing panels will be more helpful after 5 year when I switch to new ToU rates. Although I may generate more than I consume at the end of the true-up period, which will make ToU irrelevant, is that true?

Between west and south facing panels around here, and in spite of what some may say, without obstructions/shading, south facing will produce more output and more revenue to offset an electric bill than west facing.


Theoretical ideal is a tilt if about 30 deg. or so and an azimuth of about 200 to 220 deg. or so, +/- a bit. Most of us are stuck with fixed roof orientations, so unless you are ground mounted, optimum is a moot point. Still, south facing or close to it will almost always produce more annual output and bill offset revenue than west facing.