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Solar Shingles – Better Than Panels?

One of the newest types of solar photovoltaics (PV) available for home owners is the solar shingle. These are replacement shingles for standard asphalt (they are also available as Spanish tile replacements) on the rooftop. These solar cell arrays are made to look like the asphalt shingles they replace.

For the suburban prepper, this makes them an ideal camouflage compared to large, obvious solar panels. It also makes them nearly impossible to steal. In addition, they are easier to maintain, have a good lifespan, and more. These more aesthetic solar options have been around for about five years with recent breakthroughs making them more affordable and available than previously.

These photovoltaic shingles use thin-film solar technology to retain the flexibility of the asphalt they replace and are sized and colored to match. Several companies in the industry are now manufacturing them, including SunPower, Dow, Atlantis Energy and others.

How They Work
These solar shingles work just like conventional solar panels. Sunlight hits solar cells, which convert it to electricity. The shingles are sized at 12×86 inches – the size of conventional shingles. They can be stapled directly to the roofing cloth (often called “tar cloth”) as are conventional shingles. Older PV shingle designs required vented plywood decking for heat dissipation and pre-laid wiring before the shingles were put into place. Newer designs eliminate these requirements.

Installation takes about ten hours for the average roof, putting these solar shingles on par with their asphalt counterparts and making them lower per watt to install than traditional panels. The circuits are automatically connected through the overlapping shingles’ connection, making the electrical nearly wireless in its installation.

Desired voltages and total output depend on the number of shingles installed and the converter used. Output is DC, of course.

Comparable Output and Longevity
Solar shingles have a better sunlight absorption rate than traditional solar panels thanks to their wide exposure. They are made from amorphous silicon, which allows higher exposure to sunlight without the requirement of a glass covering, which can filter some light.

PV shingles shed moisture and provide weather protection in the same way their asphalt counterparts do and stick to one another using the same EVA compound. Their expected lifespan is 20 years, double that of many asphalt types and equal to most solar panels. In most southern areas of the U.S., they can repay their cost within five years in the electrical savings they produce.

Each shingle produces between 50 and 200 watts, depending on its size, exposure, and specifications. The average roof of about 2,000 square feet, covered in PV shingles, can produce enough power to provide the home’s required electricity for the day. Most installations are tied to the home’s electrical and to the grid, allowing the homeowner to sell excess electricity to the utility and use utility-provided power at night or when the roof is not producing enough. Off-grid storage is also an option, of course.

Cost Comparisons
Currently, the national average utility power cost is about 10 cents per kilowatt hour. Most solar PV installations cost about 30-40 cents per kilowatt hour. Solar shingles cost 20-25 cents per kilowatt hour. In areas like California or Arizona, the solar roof can pay for itself in 5-7 years on average, whereas in areas like Boston or Seattle, it may take 15 years to get the same return.

Solar costs are dropping, however, thanks to increased competition and better, cheaper technologies. At the same time, utility costs are on the rise nationally, especially in areas where PV is more effective. Although a full rooftop of solar shingles may not be the total answer to off-grid power, it can be a major contributor to a full system.

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