Wednesday, September 27, 2023

Solar power on a good day

Last May we installed solar panels on our roof capable of generating 5kW of electricity per hour - this is of course when the sun is shining. When the VAT was eliminated and SEAI grants added, it was an attractive proposition - we reckon it will pay for itself in about 5 to 6 years. So - four months later, how are we doing?

Of course, the summer of 2023 was not a great summer for sunshine. The best day for electricity generation was on 3rd June when our system generated 38.65 kWh. You can see from the green line below that at peak time (early afternoon) almost 5 kW was being generated per hour. 

One of the reasons for getting solar power was to avail of the opportunity to charge my car with cheap and possibly free electricity. You can see above from the red line that I charged the car from about 13:30 until 16:00 (the second peak is the immersion heater coming on. The car charges at a rate of 8kWh, and for most of the charging period 5kWh was produced. This means that it was only slightly better than half price night time rates. So - only on really sunny days does charging at this rate make sense - I have since reduced the car's input from 8kWh to 2kWh. It takes longer, but is effectively free.

We also generate excess electricity that is automatically fed back to the electricity grid. We should get about 21c per kWh - on the same day as above, we should have received €4.83 from our supplier, Electric Ireland. However, as we don't have a smart meter in our house (though one is coming soon) we only get an estimate of electricity generated, which is way lower than what you see on the chart below.

So far, solar power is a positive experience. It's great on sunny days when 5kWh can be generated - however, when a cloud blocks the sun, this figure can drop to 1kWh. On rainy and dull days, very little is generated (more about this in next post), and of course the winter is coming!

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