Anyone use solar panels at home?

I think the swamp cooler was around 5 years old when I bought the house, so I assume it had never had any maintenance. That greenish stuff was growing all over the inside of it, I went through a couple of gallons of bleach that afternoon.

Depending on conditions, the air can be very dusty in SLC too. Actually much more so in a place like St George. I haven't lived there in 7 years but still regularly visit.

Actually, the newer swamp coolers with plastic construction seem much more resistant to sediment and hard water buildup. That old house I bought didn't even have a water softener, and after I installed one I sure wasn't going to pipe softened water up to the swamp cooler. I would have had to have recharged the softener every day or two.

I think a lot of the buildup was scale buildup from the hard water.

 

The green stuff was probably not bad for you ... they always tell you to look for signs of life in a stream before drinking from it for a reason. I used evaporative coolers when I lived in a dry climate for 25 years, and they work great. You are using most of that water in the reservoir several times a day when its running, so you don't have a chance for things like Legionella to form. They are pretty safe. There are also tablets you can put in them that are a mild sanitizer, but if you are using the cooler frequently, you don't have a problem ... the water coming in has enough sanitizer in it already if it is city water.

 

Two things I'll add:

Federal Tax Credits
Federal Energy Tax Credit of up to $2,000 or 30% of the total installed cost for the tax years 2006 and 2007 ... not subject to the cap of $500 for other energy credits. See http://www.energystar.gov/index.cfm?c=prod...r_tax_credits#4

Beware of Appliance Energy Claims, Especially "COMBO" Units
I work for a major manufacturer of water heating equipment, and I see this stuff sold the wrong way all the time.

Carefully research any claims of high efficiency gas fired appliances. The ratings you see are "up to ..." and include claims of 97% or higher efficiencies. Most of the tank type gas fired water heaters have efficiencies of around 82% to 84%. To get higher than that, they have to start reclaiming some of the heat lost up the flue pipe. When you cool those flue gasses to reclaim the heat, it stops rising, so you have to develop a way to evacuate the flue gasses, or people die. So they incorporate additional expensive components such as fans, stack pressure switches, hot surface ignitors, etc. The appliance may have to be vented in stainless steel, which is very expensive. Some can be vented in lower cost plastic materials. In any case, instead of $200 or $300, you have an appliance that sells for $5,000.

When the heat is taken out of the flue gas, the water vapor condenses, and you have to deal with the condensate. Some communities require you to neutralize it before putting it down a drain (it is mildly acidic, so you don't want to discharge it into cast iron drains). Because of the laws of physics, the appliances only condense when the inlet water to the system is lower than about 100 degrees F. So if you are looking at a combo boiler/water heater that is a condensing unit, where you have to keep your boiler water at 135 or above for radiant, or 180 or more for radiators or baseboard, you will never see the higher efficiencies. (Technically, "never" is a word I shouldn't use, as there are brief periods where the boiler will condense and you will see the 97 - 98% efficiencies, but if you have one of these units, and aren't seeing a steady stream of condensate out the drain tube, you are running at 85% efficiency ... the same as the cheaper units).

"Instantaneous" or "on demand" water heaters will use the inlet water temperature of the source water, which will be down around 40 - 60 degrees F in most places. So they make sense as a high efficiency condensing unit. But realize that you don't heat any water until you turn the faucet on, and the water has to run for several seconds until the hot water gets to your tap. That's not unlike what you have with a storage tank system, but people get confused with the "instantaneous" moniker. You also are limited to from 3 to 5 GPM of hot water; that's enough if you change all the faucets and showerheads in your house to low flow, but if you are the type to take out the flow restrictors, these units are not for you. And, most of them won't fill a bath tub with hot water.

The most efficient form of water heating is still electric ... nearly 100% of the energy used is transferred into the water as heat, no matter the temp of the water. But electricity is more expensive to use than gas.

If you are planning on using solar cells, though, I would think installing electric water heating would be a part of that plan.

 

Can you expand a little on that last bit? If an on-demand water heater produces 3 GPM of water, wouldn't it fill a 30-gallon tub in 10 minutes?

I'm interested in this because I'm thinking about switching to an on-demand system; the one thing I'm concerned about is not having any hot water at all in the event of a power failure (whereas with a traditional water heater, you still have the heated water in the tank).

 

that is pretty hot water you are talking about. you will have to mix that with some cold water so the tub could be filled quicker than 10 mins

 

Thought I would chime in on this coversation. We've lived off-grid with solar and wind for 15 years and because we built from scratch were able to put in every energy efficient bell and whistle that we could think of; hence our monthly electric consumption of 90 kwh. You can check it out at our website: www.sagemountain.org. But back on subject, we have used propane on demand water heaters for years and they can easily fill a tub. Also, if you are considering solar electricity DO NOT consider electric hot water heating. While electricity is 100% efficient for heating water, the AMOUNT of electricity for such heating is enormous. Example: one 5000 watt heating element cycling on and off 24 hrs. a day (most heaters have 2 of them). 5000 watts of solar electricity will cost about $40,000! Better to try to use natural gas, solar hot water heater, or propane than electricity for water and space heating.

Christopher B
Whitehall MT

 

I agree, but you had the benefit of buiding from scratch. If you are already in an existing home, it's alittle more difficult, especially if it isn't plumbed for gas.

For us, the best bet is to stay ON the grid, that way when we need more electricity, we get it, and when we don't, we sell it back. During the peak hours of the day, no one is home, so the AC is set higher, there's no hot water being used, so cycling is minimal, and most everything is off. So at peak production, use is at a minimum. Yes, electric is more costly, but it is manageable.

 

I would use natural gas to actually heat the water -- but the tankless units use electricity for ignition and to power the thermostat.

 

I've been offline for a month, learning to transfer stuff from my 5-yr. old P.C. to my new Mac Mini, so just tuned in to Prius Chat again. (Yes, it does take many hours for some of us pre-1930's to adapt.)

The 1000 sq. ft. shop my son-in-law and I built 15 years ago included design of solar hot water for the full bath at the S/W corner. The single panel (4' x 10') faces due south at a fixed angle to capture the average max solar radiation. This was before PV became feasible, so includes cumbersome recirculation and freeze protection, even though night temperatures rarely reach below 30 degrees F. on the central CA coast (experts told us that reverse radiation can freeze water in the copper collector at temperatures as high as 40 degrees).

The only use out there for solar heating was bathing and cleaning greasy mechanics' hands, so was huge overkill, since the 70 gallon storage/recirculation tank stayed hot enough to scald hands even on sunny winter afternoons. At the time, my primary reason for designing solar was to eliminate the extension of natural gas lines, though beating utility companies was satisfying. I never tracked the consumption of electricity to run the recirculating pump, because our "expert" said it was insignificant.

I appreciate the updates on PV from members, and am looking into a whole-house installation, and conversion of more gas appliance use to electric. Even though we are on PG&E's E7 time-of-use rate, it begins to look sensible, even on a straight $ basis.

 

The problem people run into is the loss of heat off the surface of the water if you are filling the tub at that 3 gpm rate. You are mixing about half with cold water (depending on how hot you want the water), but even at 5 or 6 gpm, the heat loss off the top of the water is greater than most people like. Most bathtubs have a 1/2" spout that is unrestricted, and they can draw 10 - 12 gpm. That's 5 or 6 gpm (or more) from the 40 gallon tank, and the rest from the cold water.

I don't have the exact calculations with me here at home, but I'll get them and post them for you. I'll check with our Applications Engineering department to make sure my "practical field experience" matches the specs on these things.

 

Electric water heaters are hungry beasts. My brother's got one (50 gal capacity) and it uses as much energy in a year as our entire house (granted our water heating is done with NG)... about 4.3 mWh! If instead of wasting money on more solar panels also install a modern solar thermal system. That makes a lot more sense. If you can't do that put a timer on your electric heater.

 

There are some calculations that give you the "recovery rate" and "first hour" rate of the water heaters. I'll get those and post them.

My comments are from the standpoint of complaints I receive ... people just aren't happy with the performance of a 3 to 4 gpm hot water output if they take baths. They end up adding "booster tanks" and pumps to circulate the water and warm it when the booster tank cools off.

The colder the area you live in the worse it gets, both because the heat loss off the surface of the water as you are filling the tub, and because the ground water you are mixing it with is colder. Most people like baths that are slightly warmer than body temperature, about 100°F. Where codes exist for this, the output at the tap can be no higher than 125°F. I think using 3 GPM of 125°F water and just 2 GPM of 50°F ground water gives you 95°F water, if I'm calculating that right. That's not warm enough for most people. If ground water drops below that, and it does in very cold areas, then its worse. It helps if you can boost the water temp to 140°F, but then you really should install anti-scald valves to prevent burns.

Solar heating of water itself is probably more cost efficient than the conversion from solar energy to electricity to heat in the water. But I was talking about the difference between the "new" tankless "on demand" water heaters and the tank type, and the confusion that may cost consumers money. (My company sells both, so I don't really care which one people buy. But they should not be mislead by the marketing of efficiency numbers that they will never really see).

 

Will (and anyone else): Contact me off chatline at my email address: [email protected], and I'd be happy to share specifics on our system.
It's performing quite well. Our all electric house is operating virtually free on solar energy during the summer months, and at about 30% solar efficiency in Nov-Dec-Jan.
More later,
Bob

 

There are different sizes of on demand tanks.

What I'd like to know is....should I install a water softener in conjunction with the on demand tank? I've read that if you have hard water installing a softener will greatly extend the life of the on demand system, and since it will be so much more expensive than a conventional water heater I need the lifespan to be as long as possible.

 

Get the softener! Regardless of anything else you do, this will increase the effectiveness of your cleaning appliances (dishwasher, clothes washer, etc.) and decrease the buildup of scale on fixtures and appliances. I LOVE my softener. I recommend you fill it with potassium chloride (KCl) instead of sodium chloride (NaCl). The NaCl is bad for indoor plants and not particularly good for YOU. The KCl increases the potassium in the water to the point where your normal water intake will give you about as much potassium as a banana, and it won't harm your plants. Any modern salt-type softener will work with either NaCl or KCl.

 

Where would one purchase KCl? I've not seen it for sale locally.

 

Here in Santa Clara the local Home Depot stocks both NaCl and KCl. No problem finding it. It's more expensive than NaCl (about 2x) but well worth it IMHO.

 

Ah thanks. I'll go check it out next time. I appreciate the tip.