Your not stupid Mart but a schoolboy error.Mart wrote: ↑Sun Jun 18, 2023 1:33 pm Slight digression, but talking about a block of flats, that was one of the examples from the PV trolls, going back a decade or so.
People in flats etc etc, can't benefit from PV, blah blah blah, ignoring of course investing in a solar farm, or even better now, something like Ripple, with an actual impact on your bill.
But, getting to the point, I always argued that a block of flats would be great for BIPV* (building integrated PV), or simply retrofitting, by cladding the outside with PV panels on sunny sides. Obviously the cladding argument got tricky after the Grenfell Tower disaster, as trolls could throw 'oh great, cladding' comments in, despite the obvious differences.
For generation comparisons, popping a PVGIS pin on my house in Cardiff gives 1,026kWh/kWp for south facing, and optimised pitch of 39d, whilst south facing at 0d pitch is 855kWh/kWp.
For want of a better calculation for area, I'm just going to pick my house (1930's semi-detached 3 bed, but of course many flats will be smaller than 3 bed), which has faces of approx 5m by 5m (ignoring roof), so 25m2, then half that for windows, so 12m2, maybe 2.5kWp, and 2,100kWh's pa. That would be useful, I think. Better still would be if they are 45d off south, so have a SE and SW facing wall. To my shock, those are 855kWh/kWp pa too (unless I'm doing something stupid), so that's ~4MWh's pa.
Of course, now I'm picturing a row of tower blocks, all laid out like dominoes in a south facing row, so only one does well.
0d is a flat horizontal panel, hence 45 degree off south gives you the same answer as would a north facing one.
90d is a wall mounted one.
Surprisingly though its still not that much lower.
