Solar Power
So how much sun do we get in the UK? Using this tool [1] I created graphics for the average mid-day intensity of sunlight month-by-month and also the total monthly sunlight received
The sunlight intensity around noon averaged 700 W/m² over May 2016 making it the sunniest month that year, although individual days had more intense noon sunshine. Sunlight intensity exceeded 1,000 W per square metre on 36 days; but on no day did it reach 1,100 W. Note that the rated power of a solar PV panel is based on it receiving 1,000 W of sunlight. So for example RS Components Model 9046156[2] measuring 1.49m x 0.67m (area of 1 square metre) is rated 150 Wp (p standing for 'peak') with an implied efficiency of 15%
The monthly figures are cumulative and also confirm May to be the sunniest in 2016 with 170 kW-h/m². At 15% efficiency this will have generated 25.5 kW-h/m² of electricity. Multiplying this figure by 1000 to convert to Watts and dividing by 31 days and by 24 hours the average power output over the whole month, day and night is 34W
Another way to look at the figures: for 4 hours around noon, if the panel received the average 700W of sunlight and produced 15% as electricity (105 W / 0.105 kW) then 4 hours x 31 days x 0.105 W = 13 kW-h/m² which is half the monthly total. Half the electricity is produced over a four hour slot (1/6 of a day), the rest over the remaining 5/6. To effectively 'smooth' the power over 24 hours you would need to be storing approaching 50% of the energy produced at the peak period