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NedS

ed110220 said:

QrizB said:

Martyn1981 said:

Plus for Spain, something I noticed a decade or so ago, when playing with PVGIS, is not just that they generate more (for any given amount of PV), but also how much less variation there is across the year.

I'm sure I'm preaching to the choir here, but this is almost all down to their lower latitude. We're just accustomed to living between 50 and 60 degrees away from the Equator!

The ~40% of Earth's surface that's in the tropics gets essentially no seasonal variation in day length.

As you leave the tropics and get closer to the poles, seasons become more distinct until you reach the (Ant)Arctic where you have periods with 24h daylight and others with 24h darkness.

We also have the misfortune of largely overcast winters. If you look at say Calgary on the edge of the Canadian prairies, it's at almost exactly the same latitude as London, but PVGIS estimates almost twice the generation in the worst month (Dec for both cities): London 43 kWh/kWp, Calgary 82 kWh. Wikipedia gives only 21% possible sunshine for London Heathrow in Dec (ie just 21% of the already short daylight hours are sunny) but 46% for Calgary International Airport. Not only is Dec the month with the shortest days and lowest sun angle, but it's also the cloudiest at least at LHR with a sunshine peak in Aug (45%).

That largely overcast weather also helps maintain our mild climate. Calgary gets a LOT colder than London in winter. I wouldn't like to say how my heat pump would perform at -35C, but I'm guessing my heating bills would be substantially higher. Would the higher winter solar generation off set the difference? I don't know.

Martyn1981

ed110220 said:

QrizB said:

Martyn1981 said:

Plus for Spain, something I noticed a decade or so ago, when playing with PVGIS, is not just that they generate more (for any given amount of PV), but also how much less variation there is across the year.

I'm sure I'm preaching to the choir here, but this is almost all down to their lower latitude. We're just accustomed to living between 50 and 60 degrees away from the Equator!

The ~40% of Earth's surface that's in the tropics gets essentially no seasonal variation in day length.

As you leave the tropics and get closer to the poles, seasons become more distinct until you reach the (Ant)Arctic where you have periods with 24h daylight and others with 24h darkness.

We also have the misfortune of largely overcast winters. If you look at say Calgary on the edge of the Canadian prairies, it's at almost exactly the same latitude as London, but PVGIS estimates almost twice the generation in the worst month (Dec for both cities): London 43 kWh/kWp, Calgary 82 kWh. Wikipedia gives only 21% possible sunshine for London Heathrow in Dec (ie just 21% of the already short daylight hours are sunny) but 46% for Calgary International Airport. Not only is Dec the month with the shortest days and lowest sun angle, but it's also the cloudiest at least at LHR with a sunshine peak in Aug (45%).

I noticed similar a while back when Edmonton Canada (for no particular reason) came up in a few articles. Although roughly in line with Manchester, it gets about 1,450kWh/kWp. Quite a surprise to me.

Though as Ned points out, colder temps, with an average January temp of -10C.

Maybe I'll just stay put, and compensate with more kWp instead - brawn over brain.