Cheap Device Harvests Both Solar Power + Waste Heat For Hot Water
Now that California has a terrific solar rebate of 30% to fund solar hot water systems; as a Californian, I’ve been looking into solar hot water systems.
One of the cheapest that would qualify for both the California rebate and the new 30% Federal tax credit, and is certainly a uniquely interesting idea, is this one that not only collects solar heat, but also captures the waste heat going up and out of the attic, rather than only warming the water with sunshine.
The Greenward Ridge Vent by Nuenergy Alternatives is simple, and is installed the same way as regular ridge vents by simply capping the roof ridge, as shown this week at the Las Vegas International Building Show.
It uses some solar power as well, and in the basement it uses the same technology as a solar hot water heater uses to transfer heat to water with a heat exchange.
Here’s how it works. The sun and waste heat from your house both heat up your attic. The heat rises to the ridge. Normally you expel the heat. But instead, this device with plastic tubes would cup the ridge. Inside the plastic tubes, an ethylene glycol and water mixture would heat up.
The mixture would be pumped down to a heat exchanger in the basement, the same way as a solar thermal hot water heater works. The heat exchanger transfers heat; preheating the water before it gets to the water heater. Normally water heaters start off with 55 degree (Fahrenheit) city water. Like a solar hot water heater, this gives the boiler a head start on that job by preheating to 120 degrees.
Forty feet of this ridge vent with the PEX pipe embedded costs about $300. A kit for a full system including the preheat tank is about $3,100. Take the 30% California rebate on this and then the Federal 30% tax rebate next year on the remainder, and it is about 51% cheaper: about $1,500. And it is something the average handy homeowner could install fairly easily.
For those who would like to add solar hot water, but do not have the space, or worry about the aesthetics, or don’t have the money for a solar hot water unit – this simple ridge cap might be perfect.
You can checkÂ your own state’s incentives and rebates at www.dsireusa.org, which a solar estimator can help you with.Â You should always get an estimate from at least several solar companies. They’re free!