Panels vs Inverter - how much oversizing makes sense?

Qyburn

QrizB said:

PVGIS now lets you download hourly historical data.

https://re.jrc.ec.europa.eu/pvg_tools/en/

Cheers I'll have a proper look at that. Just to make sure I'm looking at the right thing, is column B titled "P" the expected power for that hour, ie where it says 44.92 that would be 44.92Wh at that time?

QrizB

Qyburn said:

QrizB said:

PVGIS now lets you download hourly historical data.

https://re.jrc.ec.europa.eu/pvg_tools/en/

Cheers I'll have a proper look at that. Just to make sure I'm looking at the right thing, is column B titled "P" the expected power for that hour, ie where it says 44.92 that would be 44.92Wh at that time?

Yes.

There's a key right at the bottom of the spreadsheet, row 8800 or so!

Note that in your spreadsheet you've left "system losses" at 14%. If you want to know the generation potential of your panels, you need to zero that in PVGIS before downloading. (Most of the losses are after the panel.)

If it helps you, the technique I used was to enter a nominal inverter value (eg. 900) in cell J11, then in J12 enter "=IF(B12<J$11,J12,J$11)". I then copied that formula down the table to the bottom.

That will clip any value larger than the nominal inverter size to match the inverter.

You can then sum all 8760 values in columns B and J to get your total generation for the year in watt-hours, without and with clipping. And compare them.

Qyburn

Brilliant. Thanks