It is extrememly expensive to use solar photovoltaics to heat water. If you are going this route look into batch heaters and thermosiphons etc. If you have good solar exposure you may be able to have nearly year round free water heating.
Ken
It is extrememly expensive to use solar photovoltaics to heat water. If you are going this route look into batch heaters and thermosiphons etc. If you have good solar exposure you may be able to have nearly year round free water heating.
Ken
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We'd like to put radiant heat in the basement (concrete floor), but the upper floor will be hardwood, and the architect says that the heat won't be good for the wood, and that it won't come through very much, so it would be a waste of money to do it there...
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An architect is probably NOT the best source of information on such things, much as they would have you believe otherwise. Let the architect lay out the floorplan and other design elements, but do your own homework on the mechanicals.
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Solar suit my needs, but it may not be right for everyone. I do believe that if everyone used a little solar, say just for lighting, that our demand on non-renewable energy sources would diminish.
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Solar has its place, like your application. But when you consider the energy & materials it takes to manufacture it in the first place, it turns out it's less energy efficient than just burning fossil fuels.
That's part of why it's still so expensive.
Which may not be fossil fuels after all, but that's another discussion! [img]/forums/images/icons/grin.gif[/img]
Radiant heat DOES NOT IMPLY HYDRONICS OR IN -FLOOR installations.
For a heavily carpeted area or one where floor coverings have a significant R-Value you can put the radiant heat in the ceiling and it will work just fine. (Read on the RPA, Radiant Panel Association's site) I have three rooms with radiant ceilings. Two have tile floors and one has heavy padding and plush carpet. This DOES NOT make for cold floors. The floors are heated by the radiant heat, just not as much as having the radiant in the floor. Some radiant systems are intended to be floor warming systems and are not intended to be the only source of heat. Mine are heating systems, a much larger engineering problem.
Radiant ceilings are a particular advantage where you have carpet and or a high percentage of floor space covered with furniture. The radiant heat in our bedroom ceiling easily heats the top surface of the carpet and feels toasty to my bare feet. It is also nice to feel the radiant heat beaming down from the ceiling, heating you immediately rather than having to heat the room or the air in it.
Btu's is Btu's as far as replacing heat lost due to infiltration and the delta T inside to out through the R-value of your walls, ceilings, and floors (as well as the U-value of your fenestration.) So if you are controlling room temp with an air based stat there is little difference between in-floor radiant and in-ceiling. You can do walls as well but hopefully not within picture hanging height. My only hydronic heat in the walls is in a walk-in shower and it feels GRAND.
To reduce your propane requirements install a solar water heating system (with propane backup.) Don't even consider using PV to make electricity to run any kind of heater that is just too ridiculously stupid. The more you can do solar direct with no batteries involved the better. There are battery free well pumping systems but you need an elevated storage tank for water delivery or else you have to use storage batts to run water after dark.
I have resort property in Baja California del Norte and it is in a mandatory SOLAR only zone. We are prohibited from getting or banding together to get grid electricity. All my neighbors have solar installations of various complexity and design AND BACK UP GENERATORS. We have propane available but no natural gas. Water is trucked in. I have seen it all. some designs work some don't.
I have been a long time subscriber to "Home Power" and recommend you do some reading there. Be warned in advance that of all the solar installations depicted in this great publication NONE were a financial success compared to grid power when it was available. In all instances there was no economic incentive to solar electricity when the grid was available. If you have the money and make the personal commitment to do it because you want to do it then have at it but don't think it will ever amortize itself and come out ahead. Learn how to do a net present value calculation, do the math, and then you'll know the truth. Use realistic lifecycle analysis when estimating battery life and how frequently you'll be dependent on your generator for battery maint or periods of inclement weather.
Know the truth and it will set you free! If that doesn't work, eat prunes.
[img]/forums/images/icons/smile.gif[/img] [img]/forums/images/icons/smile.gif[/img] Pat [img]/forums/images/icons/smile.gif[/img] [img]/forums/images/icons/smile.gif[/img]
"I'm not from your planet, monkey boy!"
One coulkd also work it out with a slide rule! [img]/forums/images/icons/grin.gif[/img]
Egon
[img]/forums/images/icons/crazy.gif[/img] You mean a slide rule like the 12" K&E Deci-Lon that is here in my desk; the one that I bought brand new in '61? Or the battered 5" magnesium Pickett (the third one I've worn out)that has ridden a zillion miles in my shirt pocket? [img]/forums/images/icons/smile.gif[/img] I've never been comfortable punching a calculator to do those quick pumping horsepower estimates; they's nothin' beats a good slide rule. [img]/forums/images/icons/wink.gif[/img]
CJDave
Thanks for the info, Pat.
I recently discovered Home Power, and it has some very good information.
Our home is a location that is too far from the grid for it to be cost efficient to tie to the grid. Our property is about 1/2 mile from the nearest pull box, and we would have to put it underground. In addition, our home is another 800 feet from the border of the property. Cost to pull the electricity is $25/linear foot. Cost to trench is another $25/linear foot. Believe me, solar will be MUCH cheaper for us.
It's just so difficult wading through all of the options. Our plans are almost to the point of sending them out to bid, and we've just now discovered all this new information about heating and cooling - all of which could substantially change the amount of the bid.
Thanks to everyone to has contributed their thoughts, opinions, and experience.
lliefveld, Ahh, that puts a different color on it. Nothing like a long underground distribution run to tip the scalse toward alternative electrical plans. In some ways you are in the same sort of situation as the Mexican situation I mentioned. To be successfull without spending a mint you will be making some lifestyle changes. You will be learning more about lead acid storage batteries than you ever thought you'd want to know in your wildest imagination. Too bad you don't have enough wind to give a decent payback on a wind generator or year round running stream with decent head for a micro hydro. Either or both of those could reduce your battery requirements.
You not only need an effective and efficient generator but you will be needing a whopper of a battery charger. Few solar installations have the current generating capability for proper battery maintenance. You need to periodically perform an "equalization" and it is a rare installation that can do that without a generator and large battery charger.
A word of caution... there are a lot more people out there selling solar than there are folks who "really know it." A parallel... This afternoon I met the guy who insulated the shop building that came with my property. He and his brother bought the equipment to apply "glued on celulose" that was blown onto the insides of metal buildings but got out of the buisness when the callbacks and complaints got to be more than they could deal with. They did everything as right as they could and followed all the suppliers procedures. The jobs didn't hold up, literally. Mine and every other similar job I know of continuously sheds chunks of insulation. The job is 24 years old but it began failing after just a couple years. It is like it has a half life.
What has this got to do with you? Well intentioned folks will sell you what they believe will be the RIGHT STUFF. There is a good chance it won't live up to the promotional hype. Solar power sales and installation companies in general have a worse track record than resturant startups.
CAVEAT EMPTOR!!!
[img]/forums/images/icons/smile.gif[/img] Pat [img]/forums/images/icons/smile.gif[/img]
"I'm not from your planet, monkey boy!"
One thing to keep in mind if you want to generate HEAT, then don't go to electricity first -- you lose too much in the conversion. Far more efficient and cost effective to generate hot water from the sun and store it fur use at night than to try to charge batteries for electric heat.
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