Solar water heaters on roof

Bob, coming from Australia i find it interesting that almost no one in New York uses solar hot water.

Pretty much every 3rd house in Australia has them. Google brands like Rheem/Solarhart for examples (albeit wont be available here, but will give you good examples etc).

deancollins

in General Discussion 4 years and 6 months ago

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Guest User | 4 years and 6 months ago

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In August 2019, lmiller wrote about good experience with solar water heaters. If you are still around, could you post or email me (hubbard@matrixeditions.com) information about who did your work? Brooklyn Solar does not deal with water heaters. Ideally we would like both solar electricity panels and solar water heaters on the roof of the townhouse we will be gut renovating. Thanks! And if anyone else has experience with solar, please chime in.

Augustiner | 4 years and 6 months ago

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what you are looking for is called ‘Solar Thermal’. There is no maintenance and the payback period is among the shortest of any energy efficient upgrade. As far as I know there are also Tax incentives available.
If you have radiant heating it could also supplement your gas boiler workload for heating.
BUT as usual tradespeople who know the technology are rare (let me know if you find one because I am just looking into it, too). There are no national norms and most guidelines come from Europe where this technology is standard with newly built homes. Unfortunately in the US energy efficiency still is considered a hobby for do-gooders with too much money.

brooklyndempsey | 4 years and 6 months ago

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I’m still here 🙂

Ithaca I’ll drop you an email directly and happy to discuss, but we opted for thermal because we didn’t have enough space for a sufficient number of panels for electric to make sense. The efficiency of thermal panels is much higher–we only had space for three panels, which is enough to produce quite a bit of hot water but not much electricity. Roof decks, skylights, mechanicals etc use a lot of space on our roof.

If we had the whole roof to use, I would have put electric panels over all of it rather than installing two different systems. The controls and installation for each system add a significant fixed cost so you probably want to pick one or the other.

Maintenance of the thermal system has been simple, but as noted you want someone knowledgable to install and support, and engineer it into the heating system.

Guest User | 4 years and 6 months ago

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thank you! I’ll look forward to your email, and I’ll give serious consideration to your point about controls and installation for two different systems not being cost effective.

BklnRefugee | 4 years and 6 months ago

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We have a property (vacation, not in NYC) where we did both solar PV and solar thermal. It is in a location where electric power is cheap and heating relatively expensive (truck-delivered propane). There was a limit to how much solar thermal we could realistically use — in the summer, we don’t need any heat, so it is just doing hot water and if we sized bigger, we’d just lose the extra production. As it is, we have 6 thermal panels and on a sunny day, we can get around 100K BTU (and in fact, I do notice that on many summer days the temp in the panels is like 200F, the thermal storage tank is at max heat and there is still sunshine, so I guess we sized too big?) The off-the-roof equipment for our solar thermal takes up a decent bit of space, so you need to consider that. A large thermal storage tank (bit bigger than a typical water heater) and a drain-back tank. Definitely more space and more constrained on where you can put it than an inverter you can hang on exterior wall next to your service panel. The solar thermal has needed more maintenance than solar PV ( PV, though, has needed zero, so it is a demanding comparison). We’ve had the circulating pump fail once, and I’ve had to fix air-locking in the pipes a few times. I am half-ashamed to admit that I listen for the sound of the circulator pump to come on and then I’m like “free hot water time! Turn on the dishwasher, throw in the laundry!”

RobertGMarvin

in General Discussion 4 years and 6 months ago

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Solar hot water got a lot of press in the miid to late ‘70s—I haven’t seen much about it recently.