On May 25, 9:56*am, Martin Brown
wrote:
On 25/05/2012 09:45,www.GymRatZ.co.ukwrote:

On 25/05/2012 06:42, harry wrote:

Such a device is pointless. *You don't need any house heating when the
sun is shining. Heat collected in Winter is minimal in the UK climate.

But if the cooling of the PV increases their output and can provide a
20+ (?) degree temperature rise to pre-heat mains cold water before it
goes through the combi. that could in it's self could make quite a
reduction on gas consumption during summer months for DHW would it not?

(throwing ideas in the air for discussion and dissection)

The problem is one of cost effectiveness and complexity.

There is no point in saving power usage to create vast quantities of
lukewarm water that you don't need in mid-summer if it makes the whole
installation a lot more expensive and prone to failure.

A rough rule of thumb is that summer DHW is less than 10% maybe as low
as 5% of peak winter space heating requirements. We are just too far
north for solar power to be sensible without market distorting FITs.

--
Regards,
Martin Brown

Quite right. But that depends on the price of fossil fuel and PV
panels.
Nuclear power is subsidised too.
If I want free hot water, I can turn the immersion heater on when the
sun is shining (PVpower). if I am feelng public spirited, I turn on my
solar thermal array.