Chart Details

The total of 3208 kWh shown was calculated using the NREL calculator which is provided by US National Renewable Energy Laboratory using default settings of panel angle of 20 degrees and oriented due South. NREL takes account of the local weather.

How much electricity does an average Scots household consume? According to DECC (now Business, Energy and Industrial Strategy) the median use in 2014 was 3082 kWh though the mean was much higher at 3602 kWh The median usage divides households so that 50% use more and 50% use less which that seems the best sense of “average” here which is used on the chart. DECC explains the divergence between median and mean largely by the fact that some people heat with electricity and they use a great deal more (over 5000 kWh).

People use more electricity in winter than summer though it is rather less than you might think. In 2015 with data extracted from Gridwatch we used about 25% more in January than we do in June:

The red bars on the chart are derived by multiplying the total household use of 3082 kWh by the proportion used in each month according to the monthly demand chart.

Many solar installations are not set up in an optimum way. There are some fascinating examples at Euan Mearns blog including this picture of panels in Aberdeen shaded and pointing due East even though there is a South facing roof available (the direction reduces electricity produced by some 16% - ignoring the shade). So in reality you would likely get less than chart suggests.

Comments

A commenter declared that “Solar works just fine in Aberdeen” in reply to my saying that it had a role to play in Abu Dhabi powering air-conditioning exactly when it was needed, but not in Aberdeen.

The fact is that at the Winter Solstice there are only 6.4 hours of daylight in Aberdeen (calculator here) and the sun at noon is only 9.35° above the southern horizon and it’ll be cloudy anyway. You need electricity in the winter and in Aberdeen you won’t get much from solar.

Of course if solar panels were free then you might as well install them - if 4kW give you a a sixth of what you need in December then install 24kW. But they are not. Googling around it seems the present cost of 4kW solar panels is between £6000 and £8000 (hard to get an exact figure without signing up for a quote). 24kW would cost what is for most people a fortune.

There is always the optimistic talk about battery storage. You can buy that. 4kWh of battery storage by the German company Sonnen costs another $5995 (in the USA) - of course the December deficit is about 250kWh. That is just not economically feasible.

“Not economically feasible” - that is why solar does not work in Aberdeen. In the end enthusiasm and its subsidies fade and the economics wins. Always.