Week two update

It's a little later writing this than I intended as pesky brother-in-law (   ;-)   ) decided to phone and tell me how his system was operating. He was also asking if my large spreadsheet for entering power data into could be passed onto another person who generates solar power. No problem. One of the points we discussed was that it would be a good idea for Installation Company to ease their customers into the Feed-in Tariff by providing at least a checklist of the hoops they have to jump through to claim the tariff. It's an onerous business and it wasn't clear to me. In particular, installers would be doing their customers a favour by getting them to claim as early as possible. A good few sunny days can go by before the FiTs are applied for and serious money can be lost, as happened to me last week.

So, onto the readings for this week. There wasn't as much Sun with a lot more Atlantic air passing over, so no maximum days:

Day 8: 17.5

Day 9: 16.1

Day 10: 13.7

Day 11: 15.5

Day 12: 5.5

Day 13: 11.3

Day 14: 14.0

That's a total of 93.6 units. However, day 8 was still prior to my FiTs claim so the financial return is less than it would otherwise be at £31.43. The running average since I started is 13.26 units a day which is excellent and well ahead of the 6.85 annual target. It's also becoming clear that when it comes to buying power, I'm using about 10 units a day less than before which represents about £1 a day financial saving on top.

One interesting fact during the week is that my son caught the inverter stating a momentary power output of over 3,600 watts. That's ever greater than the array's rated peak output. How can that be? Here's my theory:

A bright overcast sky can easily generate getting on for 1,000 watts, whereas a blue sky before the Sun gets to the panels generates only about 200 watts. I suspect it would be true to say that blue sky is relatively poor for solar power. So compare two situations. The first is where a bright Sun is in the middle of a clear blue sky. Presumably all but 200 watts of the power is coming from a direct Sun - say 2,800 watts. Now suppose we have a lot of broken cloud and a strong Sun shining through a gap. Could we then have 2,800 watts from the direct Sun and a further 800 watts of reflected light from the clouds - 3,600 watts in total? These numbers are just illustrative, but you get the gist?