Correlate PV output to local sunlight hours information?

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basz asked Mar 9, '21

Correlate PV output to local sunlight hours information?

Hi all, I have a CCGX which is connected to VRM. All is good, but now I would like to correlate my PV output to the number of sunlight hours in my location. Is there a way to:

a) import the sunlight hours into VRM? If yes, how does one do this and where can I find data for my location? This would obviously be the jackpot solution because then I can analyse my PV output vs sunlight hours in VRM itself

b) if not in VRM how else would I go about it? I imagine exporting the data from VRM to excel but where can I find sunlight/UV hours for my location. Have checked on wunderground if there is someone near me with that data but there isn't.

I have seen the 500+ Euro solution of mounting a UV sensor and connecting it to the CCGX but that's overkill for my home installation.

Thanks!

VRM

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Alexandra ♦ commented · Mar 10, 2021 at 08:11 PM

@BasZ

We have no local information really, not sure how many other countries do.

On victrons mppt calculator page there is a yelid graph at the bottom and you can check yeild over a year to see what months are good or bad. I have found them to be pretty accurate for our area and have sized arrays accordingly to meet needs for the bad months.

https://www.suncalc.org/#/ i have looked at this website a few times to work out number of daylight hours and other info like panle angle adjusting over the year. No way to import it anywhere though.

You can set your general location in the vrm so that you are able to use local weather data to check the current conditions like cloud cover for a site so it gives an idea of what the day is like.

Unfortunately if you are really serious about the data you want more comprehensive logging you need your own equipment for comparison data. For the most part though the solar day is much shorter than the sun day as angle of sun ro the panels and temparature affect yield among other things.

As an example we have about a 12 hour sun day right now but my solar day is between 9am and 3pm (peak yield unless cloudy). Currently playing with an east array and a north array to increase my solar day a bit.

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