A very interesting article on solar thermal and solar PV.

it’s now cheaper to heat water with a photovoltaic array than solar thermal collectors.

It would be quite interesting to make up some numbers and comparisons for New Zealand since the install cost for a solarthermal system seems to be high whereas the cost for solar PV seems incredibly low.

Of course, some contractors can beat this price, while others will charge significantly more. (In a recent comment posted on GBA, an Ohio-based solar contractor named Daniel Young estimated that the solar thermal system I describe would cost $16,250.) For the purposes of the comparisons made in this article, I’ll assume that the installed cost of a residential solar thermal system is $9,000.

I know that cost for PV has come down, however two years ago the cost was rather right of the $10K, whereas solar thermal was rather $6K – $8K. Now I realise that there is only a little more ($2K) to pay, however usually the question is whether you have those $2K or not. We do not have subsidies in New Zealand unlike other countries.

One more point to consider: if your numbers result in a tie — if your calculations show that solar thermal equipment and PV equipment cost exactly the same — remember that the maintenance costs for a solar thermal system will be higher than the maintenance costs for a PV system.

That is not entirely true. Our last solar thermal system run for 5 years without any maintenance other than filling up water. While in contrast I have heard stories of inverters failing and needing replacement. At the end I guess it comes down to what system you choose – there are better ones and worse ones.

All in all the suggested prices seem to be rather low. A hot water heat pump would cost rather ~$5K in New Zealand compared to the estimated $3K and I probably would not even get a solar PV installer out to my place for $2.5K.

From Solar Thermal Is Really, Really Dead | GreenBuildingAdvisor.com.

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