ENGINEERING ARTICLES

REGULAR MAINTENANCE: There is very little maintenance required on a PV system with no moving parts. Some system owners wash their panels, but in the Northwest, our climate tends to take care of this chore. You may want to brush off the panels if they tend to collect leaves, but other than that, your system should operate as designed with no intervention. You can also keep track of your production by reading your production meter or checking the inverter display. RESALE VALUE: The affect of a solar system on the appraised value of your home can be hard to predict, but according to a study by ICF Consulting, every $1,000 reduction in annual energy bills increases a home’s resale value by $10,000 to $25,000. However, homes are generally valued in comparison to similarly sized and aged homes around them, and if there aren't many solar homes in your neighborhood, the appraiser may not have a bar to measure against. The market for solar homes continues to grow as energy costs increase al...

Three core factors affect the sizing of your system: your electricity usage, space availability on your property, and your budget. YOUR ELECTRICITY USAGE Do you want to try to produce 100% of your power or some smaller percentage? While any excess production from month to month will carry over as a credit on your utility bill (net metering), you will not want to install a system that produces more than 100% of your power as the utility will not reimburse you for excess power produced at the end of the year. You may also not want to size the system too large if you are planning more energy conservation measures for the future. To determine how much power you use right now, look for the kilowatt-hour (kWh) consumption on your utility bill. Sum the kWh for the past year to get your annual electricity usage. Space Availability The amount of unshaded, easy-to-access, space available for mounting panels will limit the size of the system. You can use In My Back Yard (IMBY), an online t...

A well-designed solar electric system has clear and unobstructed access to the sun for most of the day throughout the year. Siting a PV system correctly is critical in order to achieve maximum power production and thus maximum energy offset and financial return. Orientation and Tilt Optimal orientation for solar panels is true south. As you move away from true south, a system will suffer production losses, up to as much as 15–25% for panels oriented east or west. However with advancements in technology these losses are decreasing as inverter manufacturers learn how to maximize off-of-south orientations. In Seattle, solar panels produce the maximum power annually when mounted at a tilt of roughly 30 degrees. Shading Avoid shading as much as possible. Even minimal shading can significantly impact power production. You will want to consider potential shading from trees, buildings, power lines, telephone poles, and obstructions like chimneys and vent pipes. Your contractor should inclu...

A PV System includes: 1. PV ARRAY Multiple PV panels installed together are called a PV array. Mounting arrays to rooftops is most common, yet they can also be located on a pole, a ground mounted rack, parking area shade covers, window awnings, etc. The PV array produces Direct Current (DC) power. 2. DC DISCONNECT The DC Disconnect is a safety device that, when manually opened, stops power running from the array to the rest of the system. The DC disconnect is used during system installation and anytime your contractor needs to work on the system. 3. DC/AC INVERTER The PV array produces DC electricity, however, we use Alternating Current (AC) electricity in our buildings and power grid. The Inverter converts the DC power to AC power. 4. AC DISCONNECT The AC Disconnect is another safety device and is often incorporated into the Inverter. Seattle City Light does not require an AC Disconnect on most small residential systems. (For details on this exemption, contact your Electric Se...

The first solar cell was created in 1883. It was inefficient by today’s standards, converting only 1–2% of sunlight into electricity. The breakthrough in solar cell technology came in 1954 when researchers at Bell Laboratories stumbled across the photo voltaic (or PV) properties of silicon while experimenting with new transistor technologies. Three years later, PV research began in earnest to develop an independent solar energy source for space technologies. Thanks to continuing research, modern commercial PV cells have improved to 11–15% efficiency. Historically, PV has been used extensively in areas that are not served by a power grid. As PV prices have dropped, and grid energy has become more expensive, PV systems are increasingly used in grid-tied applications. A solar electric or PV cell uses a semiconductor material similar to that used in computer chips to absorb sunlight and convert it into electricity. Multiple solar cells are linked together to form a module or panel. Multipl...

􀂃 Solar electric systems are safe, reliable, pollution free, and use a renewable source of energy—the sun. Most systems have no moving parts and are increasingly easy to install. 􀂃 The option of net metering, or interconnecting a customer generating system to the utility grid, makes solar electric systems more economically viable. 􀂃 Landmark federal and state legislation have created new financial incentives for owning and operating a solar electric system. If you are interested in making a long-term investment to protect yourself from rising energy costs and want to reduce your personal environmental impact, now may be the time to learn more about installing a solar electric system for your home or business.

THERMOSOLAR ENERGY: Thermosolar Energy is a technology for harnessing solar energy for heat (at low temperature); it is mainly used for the production of hot water in residential buildings, to heat water in swimming pools and for climatization plants and other application.THERMOELECTRIC ENERGY: Thermoelectric Energy: (Solar thermal power) is a technology that uses the sun rays to heat a fluid, from which heat transfer systems may be used to produce steam. The steam, in turn, is converted into mechanical energy in a turbine and into electricity from a conventional generator coupled to the turbine.