Solar Power/Heating options...

[rgramjet]

Ive been researching solar options for my house. 

Photovoltaic panels are cool but still very expensive.  Batteries, inverters and panels cost an S load.

I have a pretty good southern exposure and am planning on a solar hot water heating system.  Id like to preheat my water to 100 degrees using  propolyene glycol antifreeze pumped between roof mounted collector boxes and a heat exchanger made from an unplugged electric 50-80 gallon hot water heater linked to my gas hot water heater.

Anybody have experience with this kind of setup?  Suggestions?

[Popeye the Sailor]

When you say  "hot water heating system" do you mean to heat the hot water, as in for showers, or to heat hot water, and use it to heat the house?


Budget?


How much roof space do you have?

[the_Journeyman]

My parents have a woodstove with copper ran back and forth in the top that pre-heats water for the electric water heater.  They have 1 'dummy' heater that the water that goes through the stove is stored in, then as the live water heater refills, it draws from the dummy rather than the ice cold well.  He's a bit.  Not sure what temp it gets heated to though ~

JM

[Popeye the Sailor]

I just figure if he has the space, the other method I've seen floating about is a number of mirrors all aimed at a central water tank and used that to store up heat.


I'm sure there is more info on this out there, and that it's probably cheaper than solar panels.

[rgramjet]

Was referring to Hot Water as in showers.  Tons of roof space, facing the right way even!

Ive got gas forced air and R19 in the exterior walls, the house is Tight! 

When I rebuilt, almost went the insta-hot route instead of my 80 gallon hot water heater.  Plumber talked me out of it with the technology at the time.

[Popeye the Sailor]

Look into the mirror route. Green power companies use it-should work for you.

[Ivan]

Look into "net metering", which eliminates the need for batteries.  This significantly reduces the cost of a solar electrical power system.  When you generate excess power, your meter spins backwards and you feed power to the grid.  When you need more power than you can generate directly from your solar cells, (like at night), you draw power from the grid.  My buddy at work installed  one of these systems, he hasn't paid a dime to the Electric Co in over 7 years.

If you're a DIYer, you can save a lot by sourcing/installing the panels yourself .  You need to know what you're doing to make sure that the installation is compliant with the building codes, and you still need a licensed electrician to install the main switch that connects to the grid.

I'm waiting for the govt to announce an increased federal tax credit for installing solar systems.

[angler]

Bookmark.  I just put an offer on a house about 15 minutes ago that uses such a system.  It has a south facing roof full of panels, a 150 gallon heat exchanger (guess, but can't be much bigger and seems small) upstream from a standard gas hot water heater.  It is also used to heat the pool.  Can be set up to heat just the pool, just the house hot water or both.  It was installed in the mid 80's, so I am a bit leery as it is probably close to the end of its effective life.

[NAKID]

Depending on where you live, the local utility company may even subsidize part of the cost of the unit. In AZ, two of the local power companies will pay for up to HALF of the price of the system if you do the net metering thing...

[The Architect]

As for the photo voltaic system, in NH, it averages out to 19 years for your payback.

The domestic hot water is different.  A few questions first:

What instant hot water system did you get?  From the 100 degree comment it sounds like you have a Rinnai.

How are you getting a coil into the electric storage tank to run the water from the solar collector?

The instant hot water makes the solar domestic difficult.  But I wouldn't recommend any other hot water system.  Ideally you will need a mixing valve from the solar storage to the instant hot water.  When the temperature from the storage tank exceeds 95 degrees the mixing valve tempers the water.  (In my opinion this defeats the purpose of the solar hot water but it's better than nothing.) 

During the sunnier seasons the water in the storage tank can exceed 120 degrees.  When this occurs you want to take full advantage of it.  This will require a sensor in the storage tank.  The sensor will activate a valve to bypass the instant hot water.  The water will pass through a mixing valve to temper it in case it exceeds 120 degrees.

The option above is a royal pain in the ass but works great and requires minimal observation while functioning.  If you don't mind tinkering a little then I recommend this route.  Find a tube collector system such as these http://www.eos-solar.com/index.htm  Mount them someplace accessible.  Get a solar power pump for the system.  The pump will go on only when the sun is out.  The pump will eliminate the need for electrical wiring and sensors.  The number of solar tubes will depend on the size of your tank and what season it is.  That's why you want the collector in an accessible area.  You'll want to place inline thermostats at the solar line feeding the storage tank, the return back to the solar collector and the domestic feeding the instant hot water.  If the water temperature going to the instant hot water starts getting close to 100 degrees then start removing tubes in the collector.  You may need to play with the setup for a while to get it right. 

Also be aware that you don't want the water that's fed to the instant hot water to get too close to 100 degrees.  This will cause the instatn hot water to cycle on and off excessively and will shorten it's life span.

WARNING: YOU MUST HAVE THE APPROPRIATE EXPANSION TANK AND THE PROPER RELIEF VALVE SYSTEMS!  Or you will create a rocket in your house!

[rgramjet]

I dont have an insta hot, plumber talked me out of it.  Will be preheating the water for my 80 gallon gas h2o heater via solar.

[The Architect]

I dont have an insta hot, plumber talked me out of it.  Will be preheating the water for my 80 gallon gas h2o heater.

The drawback I see is that your heating the water in the solar storage tank while your hot water tank is also heating the water it contains.  So if you're not using any water your still maintaining the 80 gallon water temperature. 

Don't get me wrong, feeding hot water into your 80 gallon water heater is a great idea and will save you money.  Just be careful of how hot the solar heated domestic water gets.  You don't want anyone to get hurt.  Again you can temper it with a mixing valve or you can just adjust the number of tubes in the collector.

A good installer or supplier will help you size the system according to your usage.

Keep us updated.

[rgramjet]

Still havent done it yet but getting close to pulling the trigger.  Ive had some clients inquire about solar for their pool heaters and to take advantage of net metering.  First meeting will be this Thursday!

[rgramjet]

Just signed an agreement with a local company that provides and installs Schuco Solar Thermal Hot water systems.  They have been covering the Upper MD, Baltimore area and want me to open up Montgomery County, DC and Northern VA.  Could be good!

Primary product will be a Schuco, 3 panel collector system with a 105 gallon solar storage tank.  With tax credits and local incentives, a ~13k system ends up being about $5500!  A 60 watt recirculating pump is the only powered moving part.   

[cyrus buelton]

my neighbor across the street was just in texas several months ago learning how to install these.

He claims for my 1300$ sq ft condo, my roof would be lined with panels, costing about 24k installed including the parts/labor.

With tax credits through state and federal, he said in the end it would cost around 6500$.

So I guess when you are generating "electricity" your meter spins backwards, throwing power back in the grid.

Then with AEP, you get refund checks.


I can't corroborate what he is saying, but that is a long-term investment in my opinion.