For someone that wants to install their own solar water heater, the batch heater may be the way to go for them, if they live where freezing is not much of a problem. The batch heater is the simplest system to build and can produce some really hot water if in a good geographical location. These heaters are good for families with up to four members.

A tank that holds up to 40 gallons would be good for families this size. Remember that a gallon of water weighs about 8.5 pounds so the larger the tank you use the weight will add up. So, a 40 pound tank with the hardware could weight up to 500 pounds. If you use a number of smaller tanks connected in series you could increase your water capacity and keep the individual weights down.

Many batch water heaters have the tank and solar collector together in the same enclosure. This is a good set up but needs to be insulated well. If you live in a freezing location you may want to design it so the holding tank is inside a room where it is protected from the cold and the solar collector on the roof.

When you separate the collector from the tank you would be able to make a larger collector giving you more square feet to heat the water. If you could configure your holding tank to keep the hot water separate from the cold you could have hot water more quickly. If you are a DIY type you make one on your own for a reasonable cost. All you would need is a good book for instructions.