You forgot clouds. German experience shows they are at times, on average, only about 2% as effective (24 hours average, i.e. min vs max). And around 5% weekly average min vs max (battery storage over even longer periods is hard to imagine).

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elric 8 hours ago | parent [-]

Modern PV cells are pretty effective even in cloudy weather. Mine seem to produce more energy on overcast wintery days than on sunny wintery days because there are fewer harsh shadows that way.

	▲	nkmnz 4 hours ago \| parent \| next [-]
		This depends on the kind of clouds. Thick, low hanging clouds look gray for a reason.
	▲	rhubinak 8 hours ago \| parent \| prev [-]
		Make and model please. I'll be adding more solar on my roof and the current ones (sunpro SP460-N120M10) don't perform well during cloudy days.