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!