PV Gap

Brent Said:

COP for adsorption and solar photovoltaic?

We Answered:

I could be completely wrong here, but I though Coefficient Of Performance (COP) is only for heat pumps, as in the link below.

I don't see how the photo-voltaic comes into that. Electrons in the region of the diode junction are released by the photons. It is a quantum process. I could be just dumb and ignorant, but I cannot see where specific heat comes in. Temperature, yes it has an effect on the efficiency. Up to you to prove this is a meaningful formula.

The link below refers to quantum (internal) efficiency for PV cells (and lots of other stuff). This is still relatively meaningless in a practical panel, so there is an external efficiency. All references I have seen talk of solar cell's efficiency of light conversion, so Watts/m^2 for sunlight versus Watts electrical in the output. They are always quoted at the maximum power point (optimum voltage and current) because that makes the cells look best.

You can record sunlight in W/m^2 with a (solar) radiometer. You can record the electrical power W, as in volts x amps. Efficiency then is output/input. You can do the measurements (integrated) over time to get energy instead of power. You might eventually want to report the results on a "per 24h" basis.

Yes you totalize the readings taken at regular times, then divide by the number of readings. The more regularly the readings are taken the better. Things can change quite a bit in 30 minutes. You can totalise volts and amps, multiply them to get power, then divide by the number of readings to get average power over the period, then multiply by the time, to get Wh or Joules (1 Joule = 1 W.s).