Simulating Photovoltaics Production with AstroBinding

Dear Team,

We will get a solar roof within the next months. Upfront I would like to track the solar radiation in order to get an idea of “when the sun is shining”.

I think one approach could be using the Astro binding … I would appreciate any suggestions to set up a rule.

Many thanks

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Astro can give you sun position, you will probably be able to find out panel orientation, but there are so many weather variables in calculating incident light.
Is there a reason not to use the great big photocell you are having installed to actually measure this? Panel power output.

What does that mean, charts? No rules required, simply use persistence.

I give some hints in #2 here… The Astro binding provides solar radiation Channels. You can then reduce one of them, I prefer diffuse, with the percentage of cloudiness reported by your favorite weather binding.

Currently, there is no panel power output because the system isn’t purchased yet. :wink:

I was considering the “radiation” channels - but it doesn’t take clouds into account (as you’ve mentioned too).

Sorry for jumping the bandwagon I’m just trying to accomplish the same: to predict solar yield for the rest of the day. But I cannot simply take the “now” radiation value because yield is about the integral throughout the day also factoring cloudiness in at any point in time, and I think that part of the answer is missing for the OP, too.
Or is there any clever math formula or approximation ? Can I use the cloudiness value from the weather binding and multiply that by… yeah, by what ?

Clearly it can be done, but it gets complex quite quickly. There’s clouds and clouds. And for prediction you want the wind direction, strength, and cloud conditions at some distant point.
Let someone else do it maybe?

How useful or how free it is, I do not know.

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Thanks for pointing to solcast - seems to be usable data compared to my actual installation.
10 API calls/d seems reasonable - about one for each hour.

I’m comparing the next few days to my installation and report back. Maybe it’s not worth parsing the JSON :wink:


Indeed. Thanks for the link. I found another one at Forecast.Solar - Estimate your solar production.

I found this in an old rule. It was fairly similar to solar radiation values provided by the TheWeatherCompany binding.

#         #corrected_lux = str(items["Sun_Radiation_Total"].intValue() * (100 - items["Current_Cloudiness"].intValue() / 3) / 100)
#         corrected_lux = items["Sun_Radiation_Total"].multiply(QuantityType("100 %").subtract(items["Current_Cloudiness"].divide(BigDecimal("3")))).divide(QuantityType("100 %"))
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