Installation - Day 2 - Power

It was the early evening when I got home from work but the Sun was shining and its photons were already pushing electrons around the house. It had been doing so since about 5 pm and had already generated its first unit. I was delighted. My WSW roof now carries 20 panels, each capable of generating 175 watts when the Sun shines directly on them; a total of 3.5 kW.

The installer showed me his handiwork. The 20 panels sit about 10 cm off the roof and have been connected as two 'strings' of ten panels each. The panels are connected in series so that the voltage from each panel is added with the others so the 44 V max that each is capable of becomes 440 volts DC total. A more typical voltage for each is about 35 V. In the attic, each string goes through its own isolator switch before running down the cavity in the wall to the cupboard under the stairs.

This cupboard is now lined with equipment. The two DC strings go into a large red unit, the inverter, which converts their power to AC, and does so at the same phase as the incoming mains power. Its output goes to a meter certified by Ofgen that measures the power being delivered by the system. Its reading is the basis of the payment of the Feed-in Tariff. Finally the power is fed through another isolator switch and a circuit breaker for high current protection before being merged with the house's main electricity supply.

At 5:40 pm, this system was pumping out 2,300 watts. The little red flashing light on our retail meter was flashing no longer and instead glowed a steady red. Amazingly, the entire house; all the computers, monitors, lights, TV and internet systems, fridge; absolutely everything was running off the Sun. Whatever excess power was left over was being fed to the grid. The middle of the day was obviously the time to run those power-hungry appliances such as vacuum cleaners, irons, dish washers and tumble dryers.

In this blog I've avoided identifying Installation Company. This is because they have a family connection and so I cannot make any unbiased recommendation. However, on this occasion, I'll make an exception to this anonymity. I'd like to thank the folk at Absolute Solar and Wind for their service, particularly Robert and Chris. The system looks great and it's working well.

So now the fun starts - and I'm delighted that tomorrow is a day off for me. The weather is supposed to be cloudy but I'll regularly monitor the instantaneous power output from the inverter to get an idea of its profile during the day. Tonight, I'll begin filling in a spreadsheet that I've already formatted and I'll start to carefully observe how the system performs over the coming year. My intention is to post weekly performance figures on this blog that will keep followers up to date with daily and cumulative performance.

My expectation is that I will generate 2,500 units annually which is an average of 6.85 per day. Anything over that will be considered a bonus. It has to be kept in mind that the first few months of this will across the longest and brightest days of the year. Generation will appear very good at first. However, the short days of winter will be a strong counter to the optimism of summer. Wish me luck!