What should I know about buying a house with solar heating?

August 9, 2012 2:19 PM

We're getting ready to buy our first home and a house we have on our short list has a solar heating system. We know nothing about solar heating. What questions should we be asking the current homeowners about it? Are there any downsides to owning a home with this, maintenance costs, etc? We're in the Midland area of Michigan.
posted by MaritaCov to home & garden (7 answers total)

Solar heating? How old is it, is a good start. Another question is who the eff services this thing?

That is so far outside the norm that I'd be asking a bazillion questions and if it comes to a home inspection I'd have the guy who invented it inspect it.

How much money do they save? Is there a back up.

Are you sure it's heating and not solar water heating?

Here's a web page about it.

I'd also have the roof super-duper inspected (assuming it's on the roof.)

Are you sure this is the heating system, and not a water heater?
posted by Ruthless Bunny at 2:23 PM on August 9, 2012

Maybe call some solar heating specialists in the area? Tell them you are buying a house with a solar heating system and looking for information on servicing. They ought to be happy to provide you with the information you need, newbie or no.

Also, if you get to this point, make sure your inspector has experience in such systems.
posted by RobotVoodooPower at 3:31 PM on August 9, 2012 [1 favorite]

I am assuming you mean solar hot water heating, and maybe that is tied into a hydronic heating system.

These systems can be awesome and really, really cut down on heating costs. They can also be maintenance nightmares (note: these two things are not mutually exclusive).

The big things I would look out for: trace the plumbing from the collectors back to the holding tank/heat exchanger and then back to the collectors.

Any sign of leakage? this will be water stains below the pipe anywhere or pipe of obviously different ages spliced into the line somewhere.
How old is the pipe? If it is PVC there might be a date somewhere, if it is copper no way to tell that I know of.
Does it look good, neat and is it tightly secured? if it looks like something crappy, it probably is crappy. Like too much glue on joints, pipes that are bent to make something fit, crudely hacked away structure (huge red flag here) to make room for the pipe are all signs you might have a problem.

Does it run an antifreeze mixture through a heat exchanger or does the tap water run through the system (the antifreeze mixture is far more desirable).

Are there lots of shut off valves so the system can be bypassed and/or repaired? if not when you do have a problem (and you will-its a mechanical system, its going to break sooner or later, and this is true of every. single. thing. in the house) it becomes a huge pain in the ass when it does. BTW this is a great check for the plumbing system in general. A lack of good quality cut off valves in the plumbing is a sure sign they either didn't know what they were doing or they were cutting corners during construction.

And lastly if you are not fairly handy and don't know much about plumbing, hire a plumber to come and look at it. Just offer a plumber a straight 100 or something for an hour of his/her time to check it out and tell you. Its cheap considering the cost of the house. This is true for any mechanical/electrical system in the house. If you don't like something or it doesn't match your expectations, hire a pro to evaluate. Then you know what you are getting into.
posted by bartonlong at 4:39 PM on August 9, 2012

If the solar heating system is just a way to make domestic hot water, and is a separate system with some sort of back-up heat source, then I wouldn't worry. In fact, this sort of system can save a lot of money and is only slightly more complex than a typical hot water tank. If the solar heating system really is connected in some way to maintaining heat in your house it is a whole different scenario and I'd encourage you to find a third party you trust to help you understand and evaluate the system.
posted by meinvt at 5:32 PM on August 9, 2012

First of all, "solar heat" can mean a few things.

"Passive solar design" tends to take advantage of lots of South-facing windows, "thermal mass" (aka indoor stone walls) and Northern insulation (or even inset into a hill so you largely have no Northern side) with juuuuust the right amount of overhang to keep the sun out above a certain angle in the summer. When done right, it means you need almost no heating and cooling. When done poorly, it usually errs on the side of overheating and turns your house into a furnace in the summer. Note that in the latter case, a few strategically located deciduous trees can largely make up for the error, since they block the sun in the summer but allow it in the winter.

Solar hot water had a period of popularity, but PV has come down in price to the point that you would honestly do better to use an electric hot water heater, and pave your roof with PV panels. You need a backup electric or gas system anyway, for prolonged shady periods, and the entire system ends up tons less complicated - DC to a grid tie inverter, and everything just works like you normally expect it to in a modern home.

As a fellow green energy enthusiast, I have one major suggestion if you want to maximize your home's renewable generation potential (or just minimize utility bills) - Pick a spot with enough wind for a mid-sized wind turbine. You can get 5KW turbines pretty cheaply these days, and in combination with a modest sized PV array, you can realistically exceed your average electric load year-round.

Getting back to heat, though - Passive solar rocks, but you still need a backup system. And for that - Go with ground-loop geothermal. More energy efficient that anything else I personally know of (and I've looked around, believe me!), they also work as central AC, and since they work fully by electricity, you can feed it from your wind/solar installation.
posted by pla at 5:36 PM on August 9, 2012

Thanks, everyone. I've e-mailed some of these questions to the agent. Like I said, I know nothing about this other than the panels on the side of the house and a note on the counter saying "The solar heating system works great!" for as much stock as I can place in that. Once we get some answers as to what kind it is I will be sure to ask the inspector for a reference to somebody who can check them out if we decide this house is the one.
posted by MaritaCov at 2:54 PM on August 10, 2012

When pressed further the owner admitted he had no idea what the panels did and now they will remain a small mystery forever as we have gone with a different house.
posted by MaritaCov at 7:33 PM on September 12, 2012