Comments on: On Rooftops Worldwide – a Solar Water Heating Revolution

By: Matty

Matty — Fri, 27 Aug 2010 08:54:57 +0000

Perhaps compost under snow but remember compost is aerobic so needs goodly amounts of air. Some air tubes inserted vertically thru the snow might help. We are using reed bed greywater treatment systems in cold climates very successfully simply by covering them over with a thick layer of mulch to prevent the water from freezing. So maybe Jean Pain would work for hot water, but how many months does it produce heat for? Thing I like about wood is that the tree has done most of the work for you harvesting solar energy.

By: Arian I

Arian I — Fri, 20 Aug 2010 02:41:33 +0000

P.S., I forgot to mention that a water line coil is to be routed through the compost heap ^^;

By: Arian I

Arian I — Fri, 20 Aug 2010 02:39:07 +0000

In cold climates a variation of the Jean Pain compost heating system could be employed to provide hot water. If an active compost heap is buried low enough underground or under a thick layer of soil to insulate it from cold weather, it can provide hot water for – at least – most of a winter season.

By: Mark

Mark — Thu, 19 Aug 2010 12:45:37 +0000

Yes, $200 in China, $600 in Mexico, but try getting solar hot water installed in coastal California and it costs thousands, even for the thermosiphon (cheap kind) system.

By: Matthew Salkeld

Matthew Salkeld — Wed, 14 Apr 2010 15:52:36 +0000

Great news. Solar water heating is quite a varied technology and climate specific. I expect these systems have the domestic water heated directly inside glass tubes that circulates into the tank via natural convection (this can only be done in the absence of frost unless you drain the whole system down before frost events). The tank above the tubes would be low pressure (no more than 5 psi) likely gravity fed from a roof-top storage tank (not practical in freezing climates) that you see in much of the “third” world. There is no freeze protection and therefore no heat exchanger necessary. The cost of labour to install is 20 to 50 times less than in rich countries. I just saw these systems in Mexico being installed for around US $600 – very economical.

A system in a freezing climate gets relatively complicated, you have to comply with advanced cross-connection plumbing codes, and it requires a pump and a heat exchanger. The price for us in Canada is now running US $5000 to $8000.

The lesson is simply, from an energy perspective, it is way easier to do many things in a warm climate, and some technologies are much more climate appropriate than others.

I like solar water heating but, due to the high price tag, complexity and lower solar resource, expect it may have a poor energy payback in cold climates. I expect the rocket stove water heater is more appropriate, provided there is biomass fuel on site.

Cheers

By: Oeyvind Holmstad

Oeyvind Holmstad — Sun, 14 Mar 2010 09:42:57 +0000

What I like about solar thermal heating is that it is “low tech”, I always prefer technology that I can understand myself, not depending too much upon experts. Even here in Norway you can still harvest more energy from sun thermal harvesters than from solar cells, the only problem is that in many places you must install them on the walls because of all the snow, so you cannot get the optimal angle.

By: Ed Mac

Ed Mac — Thu, 11 Mar 2010 17:15:56 +0000

Somebody show me where to sign up. I will take two for $200 today. What is wrong with a country with so many intelligent people in it that we have to depend on the Chinese for everything.

By: Bruce Zell

Bruce Zell — Thu, 11 Mar 2010 09:36:15 +0000

Thanks
Lets look into quality brands and distributors in Australia. Also we need to understand any subsidy scheme the government has going. We are into converting immediately from a worn out gas system
Cheers Bruce

By: JBob

JBob — Thu, 11 Mar 2010 02:49:09 +0000

Awesome. So if a Chinese villager can get set up for $200, what can I get here in the US for $200?