Solar Dream Home: This Chameleon House by the Missouri University of Science and Technology was part of the 2013 Solar Decathlon, showcasing stunning examples of self-sustaining houses of the present and future.
THE ADVANTAGE OF WIND POWER OVER PV? The wind often blows when it’s dark outside. But before you buy, take a look at the national wind map published by the National Renewable Energy Laboratory (NREL). You’ll see that not every area of the United States is well suited for wind-powered living. In fact, if you live in any of the Southeast states—and you don’t have a place right on the water—wind is a long shot. You will make a lot more power with a good solar PV setup.
The race is on to build better PV cells that convert sunlight to electricity. New solar films and panels are being tested that are more efficient, less expensive and lighter than ever. The current challenge is to find a more affordable alternative to the polycrystalline silicon based panels that dominate the market. But while that R&D is going on, existing solar products are becoming more practical. For example, Sanyo recently came out with double-sided solar panels that can simultaneously provide shade (in the form of an awning), and take in sunlight on both the top and bottom surfaces.
At the same time, the range of building integrated photovoltaics (BIPV) has exploded. That’s good news for homeowners. It means you can now have a solar generating system built right into your roof that looks like asphalt shingles or architectural metal or even clay tiles. And, as we mentioned earlier, many states require utilities to buy any leftover electricity you generate. One of the key improvements in BIPV in recent years has been the way they connect to each other and your home’s power system. The early products were co-dependent. In other words, when the connection broke on a solar shingle, the whole roof stopped producing. Newer systems have built-in redundancy in their wiring, and most are more modular, making replacement of a single faulty tile or panel less of a hassle.
Solar Hot Water
The availability of extremely durable hot water storage tanks—which in some cases also serve as water heaters—has made solar hot water collection even more viable. Many tanks now include a separate closed loop of a freeze-resistant liquid. That extra loop is specifically for solar hot water—so that when the sun is shining, the solar panels on the roof heat the clean water in the tank.
But when the sun is not sufficient (or you have teenagers using up the “free” hot water) an external boiler or heating system built into the tank kicks on to make up the difference.
One of the great advantages of a solar hot water system is the relatively rapid payback. In other words, if you install this year, it may pay for itself in less than three years, especially once you figure in the tax credits and rebates available.
Cogeneration has been common at large factories for decades. It’s basically a way of squeezing more work out of fossil fuels. Also known as combined heat and power (CHP) generation systems, these mechanical wonders put the waste heat generated by a home furnace or boiler to work making electricity. By some estimates, they achieve 90% efficiency, compared with 30%–40% from your local power station. If you’re already replacing or installing a new boiler or furnace, why not take it to another level and try cogeneration?