Verde Laguna: Bill promotes solar water heaters

Solar is again becoming popular. Nothing has been as powerful as the solar panel, in terms of an iconic technology for the green movement. Ironically, it is a close relative of the solar water heater — which provides higher efficiency and a greater return on investment than the solar panel.

Solar hot water systems capture energy from the sun to heat water, displacing the use of natural gas or electricity, with clean, free and limitless solar energy. The efficiency of the collectors can be as high as 85%, meaning very little solar energy is lost in the process.

That’s why the just-passed California Solar Initiative Thermal Program that promotes the installation of these systems makes sense. The goal of the $368-million program is to displace 585 million therms produced by natural gas and 275.7 million kilowatt hours per year of electricity by the end of 2017 — and expand the market for other solar thermal technologies.

Solar hot water can reduce California’s dependence on natural gas, leading to gas price reduction. The state relies on imports for more than 85% of its natural gas needs. A 2006 report by the American Council for an Energy Efficient Economy found that a 5% reduction in gas usage in California would be accompanied by a 32% drop in wholesale prices. Such a scenario would save consumers $23 billion in the first few years alone. These reductions can be achieved by combining the residential and commercial potential California could save with solar heating technology, which would be about 1.2 billon therms. This amount accounts for 5.2% of the natural gas statewide consumption, study by KEM-Xenergy.

Solar hot water is not new to California. In fact the world’s first commercialized system was patented in the U.S. in 1891.

It was popular in the state until gas was discovered in the Los Angeles basin in the 1920s and the cheap price dampened the demand for solar.

While conceptually simple, the systems continue to improve. But basically the systems include storage tanks and solar collectors.

There are two types of systems: active, which have circulating pumps and controls, and passive, which do not.

Passives are typically less expensive, but usually are not as efficient. However, they are more reliable, last longer and require less maintenance.

There are two passive systems: integral collectors, that work best in areas where temperatures rarely fall below freezing, and thermosyphon systems, where water flows through the system when warm water rises as cooler water sinks.

As for the materials, low-temperature unglazed heaters are one of the most inexpensive and well-proven renewable technologies, and a very efficient option to heat water to about 20 degrees Fahrenheit above the outside temperature.

Flat Plate Collectors, another type, is maybe the most common in use for hot water in homes and very cost effective, too. The proper installation depends on many factors, but California’s Mediterranean climate — characterized by warm summers and mild winters — is ideal for their use.

The bottom line is that an installed cost of $6,000 with an incentive rebate of $1,500 and a federal tax credit of about $1,500 results in a net cost of $3,000.

Systems have a fast payback period from two to five years depending upon the cost of the energy displaced.

This means that, while saving money, and decreasing our use of renewable fuels, by improving efficiencies with the use of solar energy, we can reduce carbon dioxide pollution caused by burning natural gas directly as well as in electrical plants, reducing global warming for all Californians.

GUSTAVO GRAD is a Laguna Beach resident and certified sustainable building advisor. He can be reached at ggrad@cox.net.