Home Improvement | 17 July 2015How Does Solar Power Work? Share article facebook twitter google pinterest Harnessing the sun’s energy isn’t a new concept, but as author Eric Smith points out in his comprehensive book DIY Solar Projects, we’re still figuring out and developing ways to put solar power–or photovoltaic (PV) power–to work. From heating a petite home solar oven to generating electricity for entire power plants, the sun is a mighty force, and solar technology is constantly advancing. But how, exactly, does solar power work? And what does it mean to have a solar powered home–both connected to an electrical grid and “off the grid”? Here is Eric Smith’s expert explanation. Our Greatest Energy Source Every hour of every day enough solar energy falls on the Earth to supply the entire planet with power for a year. The energy is completely free and non-polluting; there’s no danger of an oil spill, no mountaintop removal, no toxic waste, no smog, no nuclear meltdowns, and no monthly bill. Plus, it will keep coming for at least a few billion years. With every passing year, solar panels become more efficient and less expensive. The day when a solar panel array is installed on every roof to provide power for the home and for the larger electrical grid may not be too far off. Photo credit: DIY Solar Projects What is Solar Power? The term “solar power” has more than one meaning. Solar power is not just big arrays of solar panels. There are two essential strategies for harnessing solar power: ?The first uses photovoltaic cells to convert light to electricity; depending on the size and number of panels, cells can power anything from a pocket calculator to an entire city. However, the basic building block–the cells–have to be manufactured. ?The second type of solar power involves concentrating and converting sunlight to heat; the technology to do that is simple enough to be understood by children, relatively inexpensive, and very DIY friendly. If you can glue aluminum foil to cardboard or cover a wooden box with a piece of glass you can make a working solar collector and start saving real money immediately. Solar electric panels provide all the power for this super-efficient house. Photo credit: DIY Solar Projects Going Green with the Sun’s Power Producing your own electricity with photovoltaics, or PV, is certainly one of the most exciting and rewarding ways of going green. Homeowners everywhere are using the sun to generate electrical power, and also to heat water for their showers, heating systems, and even swimming pools. The economic benefits can be significant, and when you consider that supplying the average home with conventional power creates over three tons of carbon emissions each year (over twice that of the average car), the environmental benefits of pollution-free solar energy are nothing to squint at. Polycrystalline silicon is used in almost all photovoltaic panels to convert photons of light into electricity. Photo credit: DIY Solar Panels How Does Solar Power Work? Here’s how PV power works: A solar panel is made up of small solar cells, each containing a thin slice of silicon, the same material used widely in the computer industry. Silicon is an abundant natural resource extracted from the earth’s crust. It has semi-conductive properties, so that when light strikes the positive side of the slice, electrons try to move to the negative side. Connecting the two sides with a wire creates an electrical circuit and a means for harnessing this electrical activity. Solar cells are grouped together and connected by wires to create a module, or panel. Modules can be installed in a series to create a solar “array.” The size of an array, as well as the quality of the semiconductor material, determines its power output. The electricity produced by solar cells is DC, or direct current, which is what most batteries produce (and what battery-powered devices run on). Most household appliances and light fixtures run on AC, or alternating current, electricity. Therefore, PV systems include an inverter that converts the DC power from the panels to AC power for use in the home. It’s all the same to your appliances, and they run just as well on solar-generated power as on standard utility power. Grid-Connected and Off the Grid Solar Home Systems Home PV systems can be designed to connect to the local utility network (the power grid) or to supply the home with all of its electricity without grid support. There are advantages and disadvantages to each configuration. Grid-connected systems rely on the utility company for supplemental and backup energy. Image credit: DIY Solar Projects In a grid-connected setup, the utility system serves as a backup to supply power when household demand exceeds the solar system’s capacity or during the hours when the sun is down. This eliminates the need for batteries or a generator for backup, and makes grid-connected systems simpler and less expensive than off-the-grid systems. One of the best advantages of grid connection is that when the solar system’s output exceeds the house’s demand, excess power is delivered back to the grid and the homeowner often gets credit for every watt produced. This is called net-metering and is guaranteed by law in many states; however, not every state requires utility companies to offer it, and not all companies offer the same payback. Some simply let the meter roll backwards, essentially giving you full retail value for the power, while others buy back power at the utility’s standard production price—much less than what they charge consumers. The main drawbacks of being tied to the grid are that you may still have to pay service charges for the utility connection even if your net consumption is zero, and you’re still vulnerable to power outages at times when you’re drawing from the grid. But the convenience of grid backup along with the lower cost and reduced maintenance of grid-connected systems make them the most popular choice among homeowners in developed areas. Off-the-grid systems are self-sufficient; they use batteries for energy storage and a generator (usually gas-powered) for backup supply. Image credit: DIY Solar Projects Off-the-grid, or standalone, systems serve as the sole supply of electricity for a home. They include a large enough panel array to meet the average daily demand of the household. During the day, excess power is stored in a bank of batteries for use when the sun is down or when extended cloud cover results in low output. Most standalone systems also have a gas-powered generator as a separate, emergency backup. For anyone building a new home in an undeveloped area, installing a complete solar system to provide your own power can be less expensive than having the utility company run a line out to the house (beyond a quarter-mile or so, new lines can be very costly). There are some maintenance costs such as battery replacement, but it’s possible to save a lot of money in the long run, and never having to pay a single electric bill is deeply satisfying to off-the-grid homeowners. As mentioned, off-the-grid systems are a little more complicated than grid-connected setups. There are the batteries to care for, and power levels have to be monitored to prevent excessive battery run-down and to know when generator backup is required. To minimize power demands, off-the-grid homes tend to be highly energy-efficient. Installing super-efficient appliances is a major step towards making a smaller, less expensive solar array satisfy the home’s energy needs. Smaller steps, such as connecting chargers and other electronic devices to a power strip that can be turned off when the devices are not in use, also help by eliminating small but cumulative energy losses. If you’re interested in taking your home off the grid, talk with as many experts and off-the-grid homeowners as you can. Their experiences can teach you invaluable lessons for successful energy independence. ————————————————- DIY Solar Projects Buy from an Online Retailer In North America: In The UK: About DIY Solar Projects: Advances in solar technology have made many DIY-friendly products available to consumers, several of which will be hitting the market for the first time in 2011. These include solar water heaters, solar battery charging stations, solar powered lights, photovoltaic shingles that provide supplementary electricity, solar heat pumps, and solar panel kits that generate primary home electrical service. Among the step-by-step projects is a solar water heating system you can build and install yourself for under $1000; simple thermosyphon solar heat collectors for barns and outbuildings; or “heat grabbers” that you can fabricate for $50 in materials and position below a south-facing window to provide auxiliary winter heat. About the Author: Eric Smith has worked for many years as a Home Improvement editor. He lives in St. Paul, Minnesota. Share article facebook twitter google pinterest If you have any comments on this article please contact us or get in touch via social media.