Energy is expensive.

Mixing thermal and PVsolarPV-T

Truth is that we all would like to hold down our energy bills but unless you have a new build the issues and costs of such an upgrade would take an awful load of time to recoup. For many of us more than our lifetime and probably the lifetime of the equipment. What are the new kids on the block? Solar PV-T cells. Yes thermal and photo voltaic in one unit. As to aesthetics it is certainly better than two separate systems but does it work and is it economical? As we are asked to conserve energy and our heating bills head for Mars, this is of supreme importance. The answer is yes and no. Without going into macro economics a simple thermal system would probably take 102 years to pay back on a basic household without teenagers. For those with sons and daughters who take so many showers you would think they would be washed away, that would probably be reduced to five years! (I jest) For PV cells the equation is complicated by Feed In Tarriffs. The fact is that any return quoted will conveniently neglect to calculate that at the end of any term, the PV cells won’t be worth a lot but the same cash in the bank, whilst not paying you much will still be CASH. Now an interesting issue with PV-T cells. One expert pointed out that PV cells actually produce less power as they heat up. I didn’t know that either! With thermal cells they may start cool and as they heat up they transfer that heat to your water system. At 60/65° the system shuts down to prevent scalding and the fluid remains in the cell. This can raise up to 240°. Back to square: one PV cells output degrades with heat. So on a hot day we could assume that the PV cells, rather than cooking with gas, are effectively useless. Now I AM NOT AN EXPERT but I am quite prepared for someone to come and fit some FREE PV-T cells on my roof and in twenty five years I will be pleased to  let you all know how well they worked. That is if my nurse will allow me in case I get too excited and assuming that my memory is still intact. In the meantime I shall save my pennies and watch with interest how those installed perform.

Now here is a thought. Take that surplus heat and pass it back to the ground via a ground source heat pump. At the day comes to an end and the sun goes to bed the ground source heat pump recovers that energy stored during the day. Now before you award me a degree in climatology, I confess that this was far from my idea but a suggestion at the end of the link below. Does it work? Don’t ask me. Nearly everything in the renewable field is a house of cards. Maybe this simple answer actually is THE ANSWER. I have always said the future is not in mammoth wind farms or tidal barriers but in something simple, probably built in the man shed!

The Facts – as the manufacturer sees them!


About Dougal Quixote

Slightly mad. Always believes a cup is half full so continues to tilt at Wind Turbines and the politicians that seem to believe it is their god given right to ruin Scotland for a pot of fool's gold.
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2 Responses to Energy is expensive.

  1. Brian Bell says:

    I’m not an expert but presumably solar cells have a limited lifetime [25 years?]

    Presumably the units are then useless and worthless.

    Next comes the question of having them removed and disposed of.

    But at what cost? Will savings generated in the short term be expunged by removal / disposal costs? And the only people who make any money are the suppliers / installers / removers?

    • Solar cells installed thirty years ago are still going strong. OK age degrades them a bit. The thermal ones are actually relatively cheap(c. £400). That of course is far from the whole story. By the time you have changed your hot water cylinder, paid for the electrics and the installation, you have parted with the best part of six grand. At a suggested saving of £55 per year (Which Magazine) the return on investment is poor. As to PV-T, a simple house would require possibly two thermal cells but an equivalent installation of PV would be eight. That is why you need to look on this with great care. My reaction to these people are that they are all ex double glazing salesmen and not to be trusted. Personally I want a roofer on my roof, not a window fitter! However I don’t dislike the principle although I hate the FITs. If something is economically viable, it should stand on it’s own two feet. If it is not then a viable alternative is preferable. Like a nuclear, coal or gas power station for example. Just let us get what we pay for and don’t saddle us with bills for a scam(Wind).

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