Ive been looking into getting a solar hot water system for my home. It looks like the cost would be around $6,500. With the 30% government give away I guess my cost would drop down to around $4,600.
This is a 80 gallon drain back system with two 4x8 collectors. The seller claims that it should generate 64,000 to 65,000 btu/day, and save me around $35-$40 per month on my electric bill. I am all electric and electric cost here are around .08. But the electric company is asking for an increase.
So does this sound about right? Is it worth spending $4,600 to save $35 per month? That is about an 11 year payback, will the system last that long?
Anyone here with a system?
We've had one since early 2005, but they're a no-brainer in Hawaii. Something like 35% of residential homes use solar water and they have a 3-5-year payback.
I'd love to see your seller's unit-conversion factors from BTUs to $$s. It sounds so simple & straightforward from their sales perspective. And they know what the sun will deliver so precisely, too, within 1000 BTUs/day! Impressive!
The problem is that the payback depends on a number of factors outside the seller's consideration-- your family's hot-water use, your local temperatures & sunshine, whether your water heater has an insulating blanket, whether your house's hot water pipes are insulated and how far away from the water heater they run... you get the idea. Exterior piping insulation breaks down in sun/weather and has to be painted/replaced every 4-5 years. DC water pumps may die every 8-10 years. You may want extra temperature-limiting valves or isolation valves. Solar water tanks may only last 15-20 years. All of these issues can add several hundred dollars to the price and extend the payback. We did the math for our family and came up with $10-$15/month savings.
The best way to determine your savings would be to connect a 220V version of a Kill-A-Watt to your water heater's supply wiring and measure it directly. A second-best way would be if someone in your neighborhood has gone solar. Then you'd want to see their utility bills for the year before/after (12 months' average, especially if your winter is a lot colder than your summer). A very unpopular way to figure it out (unless you live alone) would be to shut off your water heater for a few days and see how your power use drops.
Is the system a drainback because of your area's weather? A better question might be whether it's as simple/low-cost as it can be. Ours was built with 30-year-old collectors and a used water heater so it's already paid for itself. But we don't have to worry about winter temperatures.
You may want to check your state's incentives:
DSIRE: DSIRE Home
If you get an additional state tax credit then that would factor into your payback. And it's even possible that your county/city govt might have some incentives, or that your local utility company would offer a rebate.
Finally, are you going to stay in the house for the entire payback? Only a buyer who's an engineering geek or a green zealot will give you extra money for your solar water system. Most buyers would be concerned that it'll "break" and so they'll be even more reluctant to offer full price.
Your payback spreadsheet might also want to factor in 3-5%/year utility-rate inflation. That actually tilts the calculation in the sales guy's favor but it's realistic.
