Solar Water Heater Installation Cost

Frequently Asked Questions

1. QUESTION:
   How much did your solar water heater cost you? 10 pts.?
   I live in Phoenix Arizona and they say a typical installation cost 00. But, with the power company incentive of 1300, state rebate of 25% and federal rebate of 30% that the finally cost would be about 00. I was just wondering if these numbers are accurate. Was there any additional hidden costs? About how much did it save you a month/year ? Give me all the details you can please and you get the 10 pts. I am with SRP power of that helps.Thanks

   • ANSWER:
     in phoenix it is well worth it and that sounds cheap in many places the benefits are debatable costwise, if you get big solar panels on your roof you get free hot water and a cooler house because the roof is effectively water cooled so you save a bundle on A/C

2. QUESTION:
   Price to instal a solar water heater?
   Should you install a solar water heater? The average home has a 200 liter (50-60 gallon) hot-water tank, which is effectively drained and replenished three times per day. Assume that the entering tap water is 13 degrees C and is heated to 55 degrees C. Given an average energy from sunlight of 1.53 kJ/cm2 per day, how large would the collection area (in m2 of a solar water heater need to be if its efficiency is 20%? Assume that the price of a solar collector is 5/m2. How much would it cost to install this hot water system?

   Calculate energy required to heat 1 mL of water. Convert this to tank volume. area=heat required/(solar heat/area)/eff. Installation cost = area x solar collector cost.

   I'm getting 34x10^6 m^2
   12x10^9 dollars to install

   Apparently this is wrong but I can't find my mistakes. Anyone?
   I have 4180 J/Liter giving 837,200 J to heat up 200 Liters of water 1 degree C. I multiplied that by 3 because it's drained and filled 3 times a day giving me 2,511,600J per day. I multiplied that by 42 (55-13) giving me 105x10^6J per day, altering for the change in temperature of the tank. I took that and converted it to kJ = 105x10^3kJ per day. Took 1.53kJ/cm^2 and divided by 1000 to get m^2.

   105x10^3/(.0153kJ/m^2)-----> Divided by .20 for efficiency factor and got 34x10^6 m^2

   34x10^6 m^2 x 375 to get 12x10^9 dollars

   I know this is wrong, but I just can't seem to find the mistake.

   • ANSWER:
     Eyeballing it, about 50 m^2, and 000, which is way out of line with the real world, at least, for Hawaii. Without that 20% efficiency number, the answer would be reasonable for me. I would think 10 m^2 and 00.

     Look up the "specific heat of water", and find out how many joules are needed to heat a gram (= 1 mL) of water by one degree C. That's the same number of kJ needed to heat a liter.

     EDIT:

     "kJ = 105x10^3kJ per day. Took 1.53kJ/cm^2 and divided by 1000 to get m^2."

     105 x 10^3 kJ per day. I agree. But you should take 1.53 kJ/cm^2 and *multiply* by (100 x 100 = 10,000) to get kJ/m^2. So that's 1.53 x 10^4 kJ/m^2.

     Dividing that figure into 105 x 10^3 kJ, you'll get 105/15.3 = about 7 m^2. Then divide by 0.20 to get 35 m^2.

3. QUESTION:
   How does a solar pre-heater for a water heater work?
   If you have one, are you really saving money after taking into consideration the installation costs?
   Where does one find what models are available and installers who are familiar with them?

   • ANSWER:
     I have 2 solar collectors, consisting of glass-enclosed arrays of copper tubing, on the roof with a total area of 50 square feet. The collectors face south and at a 35-degree angle to the horizontal (which is the latitude where I live). Water is circulated between an 83-gallon storage tank and the collectors by a pump whenever the temperature in the collectors exceed the temperature in the storage tank. The outlet of the storage tank is connected to the inlet of a gas water heater, and the inlet to the storage tank is connected to the cold water supply. Whenever hot water is used in the house, it flows from the gas water heater. Preheated water flows from the storage tank and that water is replenished from the cold water supply. During sunny weather, hot water is supplied at essentially no cost. The system was installed by a professional company during the 1970's at a time when the state offered a generous tax incentive.

4. QUESTION:
   How much does 1000 square feet of solar panels cost?
   How much does 1000 square feet of solar panels cost? This is for a pool with dimensions 75ft by 25ft? How much will it cost including installation fee and the water heater?

   • ANSWER:
     My Father-in-Law had around 300sqft of solar panels installed for the equivalent of around £3000 or 00. These were just the cheap and relatively inefficient black plastic tubes that were installed on his roof. This was in South Africa where the labour rates are quite cheap. The system works okay and heats a 40ft x 20ft outdoor pool to over 30C in the height of summer.

     Rather than a pool heater, I think it might be good to look at an air source heat pump to help heat the water in Autumn/Winter when you don't get enough sun to heat the pool. These will be expensive (over 00), but they will use less than 30% of the electricity of a standard electric water heater.

     Just the solar panels could cost you -20K including fitting.

5. QUESTION:
   How much does 1000 square feet of solar panels cost (pool heating)?
   How much does 1000 square feet of solar panels cost? This is for a pool with dimensions 75ft by 25ft? How much will it cost including installation fee and the water heater?
   This is for an INDOOR SCHOOL POOL.

   • ANSWER:
     the expensive way is to have solar panels make electricity to run an electric heater.

     the cheap way is to have panels heat the water directly.

     that's a fairly large pool, but it should work.
     probably not in Alaska in January.
     but then, you're not going to generate any electricity there either.

6. QUESTION:
   How much should solar hot water and radiant heat cost in Maryland, USA?
   I'm getting quotes for a replacement for our hot water heater. So far I've gotten 22K for materials and installation of a solar hot water heater (3-4 collector panels) with heat rejection and single zone open direct radiant heating to one floor (accessible through drop ceiling underneath). Both quotes include a backup hot water heating system; the expensive one would involve installing a new backup high efficiency heater by converting our propane tank to use for heating. This would be either the Polaris or 2 Takagi Jrs, one for the solar hot water and another to power the radiant heat.

   Another quote is for 12K for only the solar hot water and heat rejection using the Velux system.

   Are these really high? I've already contacted 3 companies but it doesn't look like too many people are installing them in Maryland yet. I'm still waiting on a quote from one final company. Thanks!

   • ANSWER:
     Without information of how big the footprint of the house is, and how many people the domestic hot water (DHW) is for, it is hard to say.

     You said you got a quote for 3 -4 collectors, so I'm going to make some assumptions based on that. Four 4'x8' collectors = 128 sq ft of collector. A general rule of thumb for space heating with solar is 1 sq ft of collector for every 5 -10 sq ft of house footprint (depends on heat storage, heat loss in the house, climate, etc). So, if we say 1200 sq ft house, 1200 / 10 = 120; 128 sq ft of collectors could work (again, depending on above variables). Depending on the brand, each flat plate collector could cost about 00, so 00 for the four collectors (evacuated tubes cost more). You then need a controller, storage tank, pumps, heat exchanger, plus all of the copper pipes and fixtures. Then a couple of days for a plumber to install. ,000 installed seems about right without the backup heater. Here's a heating system that costs that just for the equipment http://www.altestore.com/store/Solar-Water-Heaters/Climate-freezes-Closed-Loop-Systems/Combined-Solar-Hot-Water-Space-Heating/Heliodyne-Solar-Hot-Water-Space-Heat-1500-sqft/p6731/.

     Note, gas on-demand water heaters like the Bosch Aquastar make great backup heaters for solar http://www.houseneeds.com/shop/HeatingProducts/WaterHeating/AquaStar1/aquastar1600psmain.asp. I don't know what size you'd need.