I considered solar for hot
water, but the payback would have been nearly infinite as our hot water comes from the central heating boiler which is
wood fired, and wood can be found very cheap or even free if you look hard
enough. the reason I was thinking of solar hot water was so I didn't have to fire up the boiler in summer to have a
shower, but the price. ouch because the hotwater tank on the boiler is built in we would need one of them as well, and between that, the panels and installation (legally has to be done by a professional) the price was horrific it would never pay for itself. The "official" count on how long a electrical solar array takes to pay for itself here in Denmark is between 11 and 22 years depending on roof and usage. Basically not worth it at all.