Get Started with Solar Water Heating
Solar hot water is appropriate for nearly every household, north or south. Of course, access to good sunlight is requisite, but most people have enough of it. The first step is making sure. If you have a roof that you are sure gets sunlight for a few hours a day, even in the winter, then the next step is to survey the site with a tool like the Solar Pathfinder. Most professional solar companies have a siting tool, or they can sometimes be borrowed from a local energy agency. But if you have dawn to dusk sunlight on your roof, you’re in!
If yours is like a typical U.S. household, its residents waste a lot of water. And wasting hot water means you are wasting energy, so your next task is to pare your usage to what you consider to be the minimum. Low flow shower heads, faucet aerators, more efficient washers (clothes and dishes), and insulating pipes are the starting place. Behavior is important too, teenagers taking half-hour showers is beyond wasteful.
So if your solar access looks pretty good, and you’ve done what you can to cut down on usage, the next step is to find a professional with a good reputation. Look for someone with significant experience, who can provide both business and customer references—and then you should check them. They should be willing to come to your home and chart your usage, so that you end up with the correct system and size for your needs.
But maybe you are a DIY type, with skills that include mechanical, plumbing, and a little electrical. If so, and after some serious research, you might be able to design and install a system yourself. Certainly, all the components are available to anyone that takes the time to search them out. But capability is the big question that only you can answer for yourself.
Sizing a system can be fairly straightforward. For a conservation-minded, energy-efficient household, you can figure about 15 gallons of hot water per person per day. From there, you can determine how many square feet of collector you will need. If you get 5 sun hours per day, and need 80 gal. of hot water, two 4 by 8 ft. collectors will probably do the trick. You can be much more precise than that, but even if you are in the ballpark, you should still end up with a system that will significantly cut back on your conventional water heating. For sizing the solar storage tank, it should be equal to or greater than the daily usage.
You will almost certainly need to back up your SHW system with a conventional water heater so you will have enough hot water even during long periods of no sun, to cover deficits because of winter sun, or for those times when guests are staying with you. The choices are tankless and tank-type, and both are available in gas or electric. If you choose tankless, you will need to the kind that can accept preheated water. Then you plumb the backup heater in line with your solar hot water system.