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Old 06-12-12, 12:03 PM   #1
hedgehog
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Default what makes more sense up north

this might be a loaded and complicated question but here goes.

i heat my home with a gshp with superdeheater and would like to cut the electrical consumption on my electric hot water tank.

would it be smarter to install a drain back solar hot water heater , with a storage tank to feed the hot water tank

or

iv also stumbled across 24v heating eliments for hotwater tanks that are powered via 6 220w solar panels with a controller.

or?


Last edited by Piwoslaw; 06-12-12 at 02:18 PM.. Reason: Title typo
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Old 06-12-12, 12:04 PM   #2
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sorry , im just north of the boarder in Ontario Canada close to the lakes
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Old 06-12-12, 01:25 PM   #3
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This is actually pretty complicated to figure out.

First on pure energy use if the sun is shinning strong enough to make decent electricity with the PV it's going to be strong enough that you could more easily make hot water. So hot water is your better bet.

Now the question comes on finances. Normally hotwater tends to be cheaper to purchase and install, but that isn't always the case. Ontario also has/had an amazing program giving you really really good rates for electricity you generate and sell to the grid. It could very well be that the best financial move for you is to install PV and sell the energy you don't use to the grid using the profit to also install hotwater leaving more electricity to sell back.

It all depends on your installed costs and the current incentive rate. It used to be 70 cents/kwh for a grid tied roof mounted PV system. I believe they've reduced that now but it's still quite good.

I forgot to point out that both of these systems could be pointless if you don't get enough sun in your install location. Hit builditsolar.com and find the site assessment chart. Do that for your preferred install location and figure out how badly things are going to be shaded. Then find the section where you can look up your areas expected climate/cloud coverage and figure out how many hours of good sunshine you can expect. From there you can make a reasonable estimate on payback periods of various things.

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Old 06-13-12, 12:53 PM   #4
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Default What makes more sense in the north??

Short answere: Lots of panels.

We have reduced our overall heating cost min 20% max 50% In dollars for us a minimum of $1200 savings per year. It depends on the amount of sun. Here in southwestern Ontario the seasonal sunshine can vary a lot. The first winter I had logged the amount of sunshine and it was 2 weeks/month we had ample sun. The first winter with only two panels again about 2 weeks per month. Second season 6 panels alot of sunshine. This past winter albeit warmer but very little sun. Typically we get near 100% of our domestic hot water from April to Oct. The odd two or three days we need to turn on the GSHP. or the aux. heat element.

For my installation here it has been very worth-while. Mine is a closed loop with most panels mounted vertically. The last addition of panels is mounted on an adjustable mount. We found during the middle of June summer solstice we didn't get enough hot water with the sun being so high on the vertical panels.

The space heating is via in concrete-floor heating. With 6 hrs of good sunshine we get enough heat for 24 hrs. For our back-up we have the GSHP water to water warming the floor.

Hedghog wrote:
I heat my home with a gshp with superdeheater and would like to cut the electrical consumption on my electric hot water tank.

would it be smarter to install a drain back solar hot water heater , with a storage tank to feed the hot water tank.

I would recommend go for it. 2pcs 4 x 8 panels for domestic hot water and only if you can install in-floor heat more panels to off-set the space heating.

Randen
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Old 06-13-12, 01:24 PM   #5
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Default More sense up north

strider3700 Wrote:Now the question comes on finances. Normally hotwater tends to be cheaper to purchase and install, but that isn't always the case. Ontario also has/had an amazing program giving you really really good rates for electricity you generate and sell to the grid. It could very well be that the best financial move for you is to install PV and sell the energy you don't use to the grid using the profit to also install hotwater leaving more electricity to sell back.

I agree PV could be good but the pay-back could be over a much longer period. The Solar Hot Water is substantually less expensive to purchase and install. For me I had manufactured most of the system my-self and the in-floor heating had already been installed. The payback I calculate should be less than five years. We're into our third.

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Old 06-13-12, 01:46 PM   #6
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It probably makes more sense to increase the amount of insulation you have in the house and/or work on sealing up the house better. Its not nearly as expensive as installing solar hot water or PV.
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Old 06-23-12, 12:13 AM   #7
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my home is completely finished , including the basement so im not looking to remodel to insulate. also the attic has lots of insulation.

Im just looking to save on the hot water.
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Old 06-23-12, 06:35 AM   #8
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There is always air sealing to do.
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Old 06-23-12, 06:59 AM   #9
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Another option for your consideration could be to install a timer on your existing hot water tank to stop heating water during periods of little or no demand. I have installed a Stelpro solid state timer, with battery backup, on a system at our Church hall, along with an 8 Imp. gallon 3kW heater. Our water heating costs are now almost nothing. In Southern Ontario you can find this timer at Ideal Supply, cost about $150.00.

The interesting thing that I find is that if you carefully evaluate your hot water needs you'll likely find that that you actually use water at very predictable times, and you really don't need a lot of hot water ready all the time.

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