Anyone use solar panels at home?

I haven't been able to keep up with Priuschat lately. It's grown so large, it's hard to even scan it all. I just read this thread and would like to chime in with a few things that I consider myself informed on. They are not on topic to PVs but are very important to reducing demand so that a PV system is doable.

Godiva et al-
A vented crawlspace is a bad idea in almost any climate. The modern way to approach a crawlspace is to cover the soil with a tough layer of poly as a vapor barrier to keep the soil moisture and gases out of your home. Next insulate the perimeter with either sheet or spray foam. Leave a strip uninsulated for termite inspection if you are in an area that is subject to infestation. Completely air seal the crawlspace from the exterior and vent it to the living space. This will create a mini basement. You will lower your energy consumption, improve your indoor air quality, and your floors will be warmer in winter. Go to www.buildingscience.com for more info on this.

While we are on the subject, in most climates it is desirable to use an unvented conditioned attic with foam insulation at the roofline and no insulation at the ceiling line. This must be done in the correct manner and the climate of the building must be taken into account. No statements about vapor barriers or insulation placement should be made without consideration of the climate of the area where the building will be located.

I have extensive knowledge of building science and can answer your questions on these topics here or in a PM. PM may be better as I can't seem to keep up with all the threads anymore.

On the subject of flash heaters; gas yes electric no. Rinnai makes a gas on demand water heater that outputs 6 gpm at a 50 degree rise or 4.7 gpm at a 70 degree rise. It has a 180,000 btu capacity on natural gas or 190,000 btus on propane. That is the equivanent to about 4- 50 gallon tank type water heaters.

I live near austin tx and my 4200 sq ft home used 896 KWh of electricity in January and 10 gallons of propane. This efficiency came with no lifestyle compromises. We pump and sterilize all our water with electric(rain water). We use mostly incandescent light(dimmable). We use a hot water circulation system for truly instant hot water. Our refrigerator is old and inefficient. We will replace it someday but it is hard to justify a 2000$ purchase with a 5 KWh per day savings. We could definitely do better but because of the way we built our home, our electric consumption is about half that of our freinds and neighbors whose houses are half the size of ours. Our next home will be smaller and by then we will be able to afford the solar panels.

 

I don't think sealing my crawlspace would be very healthy for my particular home.

It is wood frame, on pillars with a perimeter foundation wall, built in 1919. There is a huge furnace in the crawlspace that heats the house. I keep the pilot light on all of the time, even in the summer, to minimize any rust problems. I'm not sure sealing it up would be really great for the furnace or healthy for me. I will eventually insulate under the floor, but I won't seal up the vents.

I think the most practical place for the water softener is in the kitchen closet where the current water heater is. The on-demand will only take up half the space so hopefully both will fit. The closet is in the kitchen so I don't have to worry about an insulating blanket in a cold garage. I have a detached garage, so having the water heater in the house means the hot water stays in the house.

 

Your situation would require the replacement of your existing furnace with a new sealed combustion 90+ efficient unit. I would guess there would be a pretty short payback on that depending on the details of your system. I recommend at least looking into it.

best wishes,

 

New priuschatter here. My wife and I purchased a 3.3 KW system 11/04. We originally ordered a 2.8 kw system(20 140w BP panels), but a misorder gave us a 3.3 KW system(20 165w shell panels) for the same price. Yippy. Actually, the best energy output we've ever registered is 2.5 KW on super bright temperate days. We love it, nonetheless. No more bills. Putting extra energy back into the grid(too bad we don't get paid for it). The whole set up cost 17K. Financially we could have done better by just banking that money and using it to pay the bills, but for the environment's sake and after 4 years of debating, we decided to go with the panels. Now we're getting my dream car, the prius. Though, my wife will be driving it cause she's got the longer commute.

 

Really, you don't get rated output? We do, with 2.4kW of Evergreeen 100s, here in Bedford, MA (~71N Longitude). Where are you located?

 

And what is the orientation? At least in the first few years, you should have a few days of rated output. Usually cool, clear days. I get clobbered on the hot days with derating.

You say you'd be better off putting the money in the bank, but I don't think that's true if you look at average returns. You'd have to pick a pretty good investment to beat investing in your next 30 years of electricity right now! I decided that I couldn't afford NOT to do it, personally. But then mine "paid back" the moment I turned it on. My monthly loan payment is less than how much I used to pay for my electricity.

 

I have this system and it works great... I've only had it for a year but from what I could read up on-line this is the defact system in Japan and supposed to be very reliable. The warm water is almost instant in kitchen on 1st floor but takes awhile to pump to 3rd. That said this combined with modern appliance and energy efficient windows etc make me pay less total heating+electricity then I used to pay in my old house that was a 1/3 smaller!).

The energy efficient system I have are no compromise and what most people would consider high-end products and yet they save me money.

I will never buy anything but the most efficient systems again.

For my next 'house' I'm seriously considering solar panels and/or wind. As I love in a condo now I'm limited in what I can do

 

Nope. We don't and we live in southern california. I saw 2.7 kw once, but I think that was some fluke. We were told by the installers that that the angle of the roof was suboptimal.

I'm glad to see that your eslr panels are so efficient. I was told by the installer that he didn't like evergreen panels. He gave me the cost as a reason. Fortunately I didn't listen to him and bought the stock almost 2 1/2 years ago for a buck forty per share. Didn't buy a lot of shares, but enough that if I sell them, ironically, the profits would cover the solar panels.

 

Now THAT is cool.

 

agreed, that is cool. I started looking at ESLR at about $3, decided to buy at $6, couldn't get the cash together before they'd gone to about $8 and change. But now it's what, around $14?

If my financial advisor hadn't talked me down and convinced me to 'diversify' more I'd be showing about $40K profit right now...

Oh well.

 

I'd love to do solar, but the big ol' oak tree in the backyard
would probably have to go for it to be any use in the summer.
.
I would want to do a few atypical things, for better efficiency.
First of all, why are PV and solar heating systems always separate?
Where does the other 85% of the energy hitting the 15% [optomistic]
PV panels go? *HEAT*. Why is nobody making panels that combine
PV on the front with a coolant loop on the back, letting the same
area do double-duty? And it seems to me that adding a few side
reflectors at close to but not quite vertical along each panel
would greatly help extract the goodies from off-axis insolation.
.
I think what I really want to think about is a large, moveable rack
mounted against the south side of the house, carrying the panels
and pivoted/counterweighted so that it can tuck right in against
the wall [protection from weather when needed] and then swing out,
up, and then *over* the roofline. A large structure, which would
obviously have to be robust against wind and have its connections
rigged in a way that could follow the movement, but rather than
worry about how much snow is piled on rooftop panels, simply lower
the rig during storms and let it never accumulate in the first place.
.
Sure, I want solar someday, but I see a lot of well-established
deficiencies in current systems. And if I wait a bit, the more
efficient panels may begin hitting the market.
.
Heck, what I really want to do is *work* somewhere I can help
develop this stuff...
.
_H*

 

They have and they do. They were terribly problem-prone and unreliable,and I doubt that they're selling any longer. The plumbing between the individual panels was a nightmare. And in my case, the only time I'd make good hot water is during the really hot days... when I don't need it. In the winter, it wouldn't make any. Much more efficienty to use a REAL hot water accumulator and a real PV system, silly as it sounds. There's plenty of heat hitting the other parts of your roof/property, might as well take 100% of the heat instead of the PV leftovers. Cheaper to produce, and more efficient to operate. The only thing you lose is realestate.

 

until the installer came for the first site visit it hadn't hit me how difficult it is to do PV in most New England suburbs. Heck, the whole east coast I guess, but I don't get out much. We've basically built our megalopolis in a forest, and that makes it pretty hard to get a spot with dawn-to-dusk solar exposure, unshaded so the single-crystal cells won't hiccup.

My refrain is "PV should be the last solar thing you do, not the first like we did!" Solar domestic hot water (DHW) gives the best bang for the buck.

I've been looking at these solar hot air heaters - AAASolar has a model (http://www.aaasolar.com/design/HOMEMAIN.html
that looks good, I've seen a competitor with less time on the market. I think this would be a good solution for retrofit on lots of homes across the country...

About the idea of getting heat from the back side of the panels, I think the big problem is you don't want the PV panels getting that warm. Thermal de-rating kicks in pretty early, so you want to dump heat not collect it there. Now if you were talking about liquid cooling and using low output temps, maybe you could get somewhere. But you'd probably be better off with dedicated thermal collectors...

 

Well, not all of it. A lot of the electros that get "excited" by the impact of the photos onto the silicon surface never make it into the ciruits that lead to the house. This is because they have to travel a long way to make it there (hundreds of nanometers). Only of the reasons that the quantum dot technology is exciting (pardon the pun) is because the distances involved are much shorter, 10's of nanometers I think.

Also, the two things sorta work against each other. In one case, the PV, you want to keep things as cool as possible so your module efficiency stays as close to the rated power as possible. Obviously, with solar thermal it's the opposite.

 

Okay, the various responses sent me off into an all-day whirlwind
of reading about PV systems. Maybe an odd way to trigger the
rathole, but it works... I understand the I/V curve now, and the
thermal derating although that particular effect doesn't seem as
severe as I might have thought. Still, I see why cooler is good.
.
Then, to follow up here, I had to dig up wherever this thread had
gone, buried under SIX PAGES of newer posts in only 24 hours.
Boyhowdy, PC is gettin' too big fer its britches...
.
Anyway, it still seems vaguely plausible that some sort of liquid
cooling loop embedded in panels could help; suppose, for example,
it was simply doing preheat for the real water heater but starting
with the 50-degree water coming in from the street ... except that
the required volume probably wouldn't be sufficient to carry enough
heat away from the panels. It would need a "heat dump" somewhere
else in the system.. maybe too complex with all the extra hoses
and stuff, but hey, the prius has liquid cooling for its inverter!
.
_H*

 

Wow, I haven't heard the word "britches" since the last age. But yeah, I think you hit the nail on the head with that last bit. I think for many people, one of the selling points of solar is its simplicity. Very simple maintainence, basically just washing dust off periodically. A combined system increases the cost and complexity but without a good ROI. Unfortunately, the ROI does matter a fair amount to most people, even the green types when it comes to laying out that much money.

 

The Oregon Energy Trust (state program) made it possible for us to install a 3.2K system (sunny Boy, BP) for under $11,500.
Net metering. For new construction only.
Because we have electric heat (heat pump) our yearly average total energy bill is around $65 a month.

eric

 

That sounds like payback less than 10 years. I'm jealous.
How much subsidy did you receive ?

 

somewhere in the area of 12 Grand.

 

We're looking at solar, in spite of not having the best overall location. Our house is shaded by a big redwood, that I'm not going to touch. But we have an adjacent field that gets pretty good sun, so we would have to go with free-standing panels. Has anybody done this in WA state? It looks like we have a pretty good net-metering program. Are there installation subsidies that I should be looking into? Will freestanding panels run much cooler?