“If every house in Florida had a solar-heated water tank, that would eliminate consumption by 17 percent.”

In a race for the state attorney general, we’d usually expect to hear about consumer protection, fraud, and corruption. So we were surprised when Lt. Gov. Jeff Kottkamp, a Republican candidate for attorney general, brought up the question of energy efficiency in a recent interview with Newsmax TV, a conservative Web site.

“If every house in Florida had a solar-heated water tank, that would eliminate consumption by 17 percent,” said Kottkamp.

He’s right they would help. But would they help that much?

According to the U.S. Department of Energy, solar water heaters are indeed a cost-effective way to generate hot water. Although they are generally more expensive to install than conventional systems, the cost is offset through long-term savings: On average, water heating bills drop by 50 to 80 percent. That also reduces carbon dioxide emissions.

First, we contacted Kottkamp’s campaign to ask about the source of their claim. A press representative told us that because water heating makes up anywhere from 17 to 20 percent of the utility bill, a solar water system would reduce our consumption by up to 20 percent.

We checked a variety of sources to see how much water heating makes up of the average utility bill. We found a few different numbers, but for the most part, Kottkamp was in the ballpark. According to the U.S. Department of Energy, it’s about 12 percent. An MSN Money article puts the figure between 14 and 20. The Western Area Power Administration says that it’s 18 percent.

But there’s a flaw in Kottkamp’s conclusion because he’s assuming a solar heater would eliminate energy consumption. Kottkamp didn’t note that most solar water heaters also require a back-up system, usually in the form of an electric or gas heater. And it takes energy to power them.

Dan Olney, vice president of operations for Suntrek Industries, a California company that installs solar systems, said he tells customers that solar heating “can only supplement conventional water heating.”

That’s why the Department of Energy says the reduction for water heating energy costs is more along the lines of 50 to 80 percent of the current cost. That means rather than the 17 percent savings Kottkamp cites, it could be as low as 8.5 percent.

So Kottkamp’s underlying point is correct, but he’s overreaching with his conclusion that it would reduce energy costs 17 percent. According to the federal estimate, the actual savings could be only half of that — as low as 8.5 percent of total energy costs. So we find his claim Half True.