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About six years ago, we were offered the opportunity to install solar panels on the roof of the dwelling house.
It was one of those deals whereby we paid nothing and the parent company received all money from generated units (kWh) not used within the property, as well as all Renewable Obligation Certificate (ROC) payments.
For those who don’t know, these ROCs are magically worked out from the total units generated by whatever renewable system is in place.
After around four years, full ownership of the entire system was then transferred to me, so it is only recently that I’ve been able to take a stab at working out the actual monetary income from this 5.5kW system.
I didn’t comprehensively grasp the intricacies of the whole thing when it was first established, and I still am a bit cloudy about most of the detail.
How good or bad is more of a grey area but roughly speaking, when the sun shines on a clear day I can put on the dishwasher and immersion heater without it costing me a penny
But I can take a crude and agricultural overview of the money coming in, and now know a fair bit concerning the type of conditions that translate daylight into money.
In a nutshell, bright and sunny days are good, and dull days are bad.
How good or bad is more of a grey area but roughly speaking, when the sun shines on a clear day I can put on the dishwasher and immersion heater without it costing me a penny.
This is because the inverter box has a constant readout which displays the amount of power being generated, and suitably bright weather sees this system churning out up to 5kW. By contrast, a slightly dull day may only be converted into about 100 watts, and very dull conditions wouldn’t even light a candle.
Payback
Of course, the bottom line here is quite simple. How much did it cost, how much does it make (or save) per year, and what is the payback timescale?
Unfortunately, some of this calculating is estimated, and some of it is accurate and exact. Firstly, at the time of installation, this system may have cost around £9,000. That bit is uncertain.
Equally unclear is the amount of money saved each year.
This is partly due to variations in the weather, but perhaps has more to do with having two teenage children.
Seventeen-year-olds have an uncanny ability to leave lights blazing in multiple rooms
Both youngsters left for university across the water just after the solar panels were fitted, so there would have been a substantial reduction in the quarterly bill anyway.
Seventeen-year-olds have an uncanny ability to leave lights blazing in multiple rooms while simultaneously using 500 gallons of hot water, claiming that they are “just popping into the shower for a minute”.
Nonetheless, my best guess would point towards a quarterly reduction of possibly £100.
Electricity prices haven’t altered much, and the bill for July to October 2012 was £314. The same period in 2019 was £98.
I have more accurate figures on the amount of incoming money.
In 2019, I was paid £206 (excluding VAT) for excess units not used within the property, and a further £935 for the ROCs payment.
If we add £100 (saved) per quarter, then a total of £1,541 may be some sort of rough estimate of the value of my solar panels.
This may or may not indicate a six-year payback, assuming you had paid full whack in the first place.
Efficiency
Other questions involve the potential decrease in efficiency of the individual panels over time, and even the possibility of malfunction at some point in the future.
I am told that newer versions are much more energy-efficient, and if we add in the lottery that is government policy, it would be hard to predict what the future holds.
I suppose the real issue here is whether I would fork out a lump sum in order to become “greener” and environmentally aware if the opportunity arose again. The honest answer is: I’m not sure.
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