To be truly independent from your local power grid and still have the capability of generating electricity during a disaster, you would need a stand-alone photovoltaic (solar panel) system with or without a battery backup. The basic concept is that the solar panels are directly connected (direct-coupled system) to a Direct Current (DC) load. This means that when the sun is shining you are generating electricity and can directly power devices once converted from DC to Alternating Current (AC).Typically households operate using Alternating Current. You can of course purchase appliances that operate on DC such as appliances found in recreational vehicles/campers and so forth. You can use the solar panels in conjunction with a diesel generator and wind turbines for nighttime use and during cloudy days. Once the sun goes down the panels stop generating electricity and there is no storage capabilities.
Stand-alone systems can however, incorporate storage batteries. Batteries are useful because the demand from the load does not always equal the solar panel capacity thus, a battery pack would pick up the slack so to speak. Batteries are also needed to supply start up surge to certain appliances where direct coupling could not provide the needed surge to start a refrigerator or air conditioning unit for example.
Grid-connected solar systems are the most common because any excess electricity generated is fed back to the power grid, and in most cases, you would be given credit for the excess to use at night or on days without sunshine. Obviously grid-connected systems require an operational power grid.
To determine the number of panels needed you would need to study your current electric bill to determine the number of daily watts used. You will also need to determine the hours of peak sunlight daily.
Divide the total watts used daily by the hours of peak sunlight daily. The figure arrived at is the number of watts you need to generate each hour. Each solar panel will produce a certain number of watts per hour depending on its size. For example, if you need to generate 500 watts per hour you would need at least five 100-watt panels. Keep in mind you can add panels later on to meet a growing demand.
For great DIY solar help visit www.earth4energy.com
Check back next week for part 2
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