DIY Solar Water Heating

Overview: How a solar hot water system works

If you've ever left a garden hose lying across your lawn on a sunny day and felt the nice hot water coming out the end, you know that sunlight is an effective water heater. Solar hot water systems of yesteryear were often leaky, failure-prone and ineffective, but the industry has matured. Today, you can choose between super-efficient, professionally installed collectors and this less expensive DIY-friendly system. And if federal tax credits are available or additional state and local incentives, you may be able to recoup your investment in a few years, and enjoy cheaper hot water for years beyond that.

Using a solar water system doesn't mean surrendering the convenience of your regular hot water system. Solar hot water systems are designed to tie in to conventional electric and gas water heaters. The tank stores the solar-heated water and serves as a backup heat source. Even if the water from the collector isn't shower-hot, you'll still save money since your tank will have had a head start heating the water. With all solar water systems, it's vital that the panels be installed where they will receive the most direct sunlight. Ideally, you'll want to use a south-facing section of roof. An east- or a west-facing roof will also work, but you'll need additional panels to collect the same amount of heat.

Solar hot water system

Closed-Loop Solar Heating System

Here's how it works. When the controller senses that the sun is shining and your tank needs a warm-up, it signals the pump to send water through the black collector panels. The heated water then flows into the storage tank before it's channeled into the heat exchanger. There, it transfers its solar heat to the cooler water coming from your hot water tank. In this closed-loop system, the water in the panel never mixes with the water in the tank, so there's no chance of contamination. When the sun is down or the temperature drops, the controller protects the panel from freezing damage by automatically draining the rooftop panels into the storage tank.