Solar Radiation and PV Generation

The installation of a Davis Weather Station in November 2019 with automatic data collection via Weatherlink means I can investigate how solar radiation measurements correlate with the electricity generation from our PV solar panels.

The solar radiation sensor on the weather station measures the sun's power (W/㎡) over the wavelength range 400 - 1100 nm which, coincidentally and fortunately, also happens to be the region of the electromagnetic spectrum used by silicon PVs to generate electricity. On this basis, we might expect the two parameters to correlate reasonably well.

On the other hand, the solar sensor is fixed in a south-facing position but pointing upwards (on the left above the small solar panel) whereas the PV solar panels are in two locations, one facing SEE and the other SSW. Some variability (scatter) in the electricity generation data might be expected depending on when the sun was strongest (morning or afternoon).

 In the graph below, I have plotted monthly PV generation data (kWh) against the Monthly Solar Radiation data (W/㎡).

An excellent correlation (correlation co-efficient = 0.96), probably better than I expected!


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