I am building in California, with solar collection for hot water. Space heating requirements are low also.
Would you build a house that uses propane for appliances and mechanicals, or would you build a house that uses electric appliances/mechanicals – the electricity being provided by photovoltaics? Or would you build some type of hybrid of the two?
Thank you.
Replies
"electric appliances/mechanicals - the electricity being provided by photovoltaics?"
How much power do the appliances take. Have you priced that much power in photovoltaics?
I would be running lights, computers, oven, stove, microwave, clothes washer and dryer, boiler, and well pump on electric sources. 2 people in 2500 square feet. Space heating is provided by in-floor hydronic radiant.
The only 2 items that I would potentially move to propane would be the clothes dryer and boiler. The oven and stove will be electric anyway - we do not care for cooking on propane.
Of the remaining 2 possible uses - hot water will be substantially provided by solar collection. So that boiler is only a secondary supply of hot water for DHW and for in-floor radiant.
Thanks.
Edited 11/23/2005 3:05 pm ET by slobuds
It is hard to imagine that photovoltaics (PV) will be cost effective, unless electricity prices keep going up. It takes about 6 years just to get the energy out of a PV equal to the amount used to make it. Make sure you look at a low water usage front-load washer, as the amount of energy required is proportional to the amount of water used.
Forget photovoltaic. Way too expensive. Use solar to heat water, with propane for when the sun doesn't shine.
-- J.S.
OK then - would you think that investment into higher efficiency water collectors, such as the vacuum tube collectors, are worth the extra expense?
The folks who show a 5-10 year payback on photovoltaics, are they just wrong?
Thanks.
The payback depends on the state subsidies that are available. Here in the land of the Green (CA), there are some pretty hefty subsidies (budget deficit? what budget deficit?) that can really reduce the payback time to 5-7 years. It also helps that our utility companies are so screwed up that they have extremely high rates. With the utility rates here, it may even be cost effective without the subsidies.
Erich
Having done some solar passive HW down around Lake Conroe, we used electric for the supplemental heat as that let us use relatively uncomplicated 120 & 150 gallon tanks (no need for flues, etc.)
Most of our calculations on buy-back were tight enough that a separate WH or boiler made them upside down. And the numbers (then) got squirrelly quick. You could get a larger conventional WH, but then you had to plumb it to your PSWH system (separate tank) or with your (getting the triple-isolation heating coil in the tank). Neither of which were very cost effective (especially factoring in the PC/plumber's learning curve, as these were all one-offs).
Probably the harder answer will be the PV system. Residence can get by with 2 4x8' collector panels (3 is better) for PSWH; but you may need more than the whole southern roof for PV (it's not the volts, it's the amps you need; amps still equal area, last I saw).
Hmm, now I'm wondering what the cost would be in KWH per therm just running a propane-powered genset . . . With "enough" PV, wind, etc., now, that might be an interesting calculation (the genset gives you a "reason" to have storage batteries, too, which means "capturing" the excess from PV better).
Here in NYC even developers are incorporating photovoltaic arrays into many new residential buildings....I say this because it's always becoming easier and less expensive to go with as much solar as possible, for a number of reasons.There are so many financial incentives now, between federal, state incentives, no sales tax, etc, that they pay for appx 1/2 the system cost.Net metering - many states have net metering where youre photovoltaic array is tied directly to the electric meter/grid (no batteries).On a simple array system that will run 1/3+ of a typical home, it can pay for itself in 5-10yrs, and then you are literally getting FREE enegy from the sun, ok stop and think about this for a minute.http://www.akeena.net/solar_energy_benefits/incentive_programsca.htmlcheck it out and good luck.Peter
There are so many financial incentives now, between federal, state incentives, no sales tax, etc, that they pay for appx 1/2 the system cost.
Shoot, back in 1982, there were all sorts of huge government subsidies, but still the buy-backs were long, and the margins slim. (You were buying house financing in double digit interest at the time, too.) I learned to be very sharp on system costs (they have a very bad habit of cutting both ways).
Net metering - many states have net metering where youre photovoltaic array is tied directly to the electric meter/grid (no batteries).
Now, I got the impression that OP was a bit too rural (using propane, not NG) to be that "on grid" per se. Also, not all net metering is good. Sunset right now means the PVs kick off right in the middle of peak demand--not the best time to buy electricity. That still suggest some sort ofstorage battery system, if only to better meter when you go back "on grid."
Now, the coolest PV install I've seen is where a curtain wall outfit used PV to power Photochromic panels on an entry canopy. When the sun was bright enough, it generated enough juice to opaque the canopy panels to make shade. Gets dark, panels clear. Very cool.Occupational hazard of my occupation not being around (sorry Bubba)
Wiring houses I commonly advise people to run the feeders and panel capacity necessary to have everything run on electricity. I also advise that gas lines be run to all major appliances that can be run on gas. If done during construction the extra cost is small.
Installing electric heat strips in a gas system is relatively simple if the electric feed is already installed. Similarly a gas water heater or stove installation is simple to change to electric if the feeder is already run.
Given that I think that in the next decades having the maximum amount of flexibility is going to be an asset. I think the energy prices, and possibly availability, are going to, or be made to, fluctuate wildly. Having an option may save you in the long run.
If you do go for a solar system make sure provision is made for maintenance. A lot of solar systems installed during the energy crisis failed early when they were not maintained. In some cases they were installed in such a way as to make maintenance virtually impossible. A shame and one, along with systems that were simply poorly designed or misapplied, that gave the whole solar energy industry a black eye.
I like solar. The idea and beauty of a well designed and implemented system but, contrary to popular belief, solar energy is not free. The sun may work for another four Billion years without us messing with it but the equipment needed to harvest that energy won't. It has to be maintained and parts regularly replaced. Same as anything else.
I would try to set up my house to use as many different forms of energy as possible while making any transitions, in changing equipment, as simple and efficient as possible. Hydronic heating systems are, from what I read, fairly easy to convert. Potential being anything from oil, wood, gas, electric and even solar.
Wood would be a good backup in most areas. Even in urban areas where scrap wood it more available than immediately apparent. Coal would be good, I guess, in West Virginia where it is easy to find. Water power in the mountains and solar in the sunshine states. Natural gas and/or propane in some areas.
I used to know a guy who had a furnace that ran on used motor oil and would heat his house and water. Very practical as he owned a couple of garages and the oil was free.
Regarding PV - are you on or off grid? On grid, depending on usage patterns you can get a pretty decent return. My 3KW system is projected to be a 13-year break-even (based on PG&E's ever climbing rates).
That includes a $3/watt rebate and a first-year state tax deduction. The California rebate is dropping to $2.60 IIRC in Jan. (I locked mine in last Dec., went live in Aug.). The state tax deduction goes away in 2006 but is being replaced by a federal $2,000 deduction. One other possible factor - through 2005 assessors can't hit you with an improvement; that protection is set to expire at the end of the year.
Check out time-of-use metering; it accelerated the payback by a couple of years for me; your milage may vary.
Now, add batteries into the mix and PV gets WAY more expensive. AND, the batteries need to be replaced - every 5 years according to the solar electric instructor at the local JC (who is running a whole electronics lab off-grid). You have to be pretty far from the grid to make the numbers work for you, and you would definately want to absolutely minimize your electirc usage if this is your situation (e.g. wood for your hydronics).
Luckily, I AM on grid. The battery proposition never did look appealing to me. And I do live in California which means that I will be able to take advantage of the rebates and other tax incentives.Are you using natural gas or propane with your 3kw system?I have not yet gone to the effort of actually figuring out what our consumption would be. With it being a new house, different part of the state, new appliances, new mechanicals, etc., it's more challenging than just looking at our current electric bill.Thanks again,
Martin
Martin,
We have NG - makes the decisions easier than if propane were part of the equation...
I talked about going with solar water heating when we were in design but no one seemed interested. One of the two biggest installers in the SF Bay Area started out doing water, but only does PV now - too many maintenance issues with water, and not a very good payback according to them. I suspect propane helps with the payback.
When do you plan to start construction? As long as your request for a rebate is mailed by the end of the year you lock in the current rate. Once the state processes the rebate request (2 to 3 months typically) you have 6 months to complete the install (extenstions are available and pretty much automatic).
Wayne
Thank you Wayne. I am getting opinions on this all over the board. Someone much smarter than me probably needs to do a real cost-benefit analysis.
Our house won't start construction until 2007. So I am afraid that we are going to have a reduced credit, and also looks like the the tax basis will be impacted by the solar as well.
Thanks again for telling me about your experiences.
Martin