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Solar for your Home or Business – The Basics

There are basically two types of solar PV systems (Photovoltaic, solar electric as oposed to solar thermal where the sun’s energy is converted directly into heat): stand alone and grid-tied.   A stand alone system is where there is no power available from the grid, like a cabin on the woods, a flagpole or sign that needs light and is too far from the grid, or a gate opener or electric fence.  A grid-tied system has the advantage of not requiring batteries, and when there is more power being produced than is being used, the excess goes into the grid.  A good primer on the basic of solar systems is at:  http://www.fsec.ucf.edu/en/consumer/solar_electricity/basics/index.htm

In a grid tied system, the grid acts sort of like a battery, because in Florida (as in most states) the utility company is required to purchase the power back, and pay the same amount for that power as they charge for the power.  This is called “net metering”.  The net metering rules in Florida state that when you have produced more power than you use, the utility company credits your next month’s bill for up to 12 months, at which time they send you a check.  This makes sense, as the amount of power your solar system produces varies by the season.  A grid tied system is less expensive initially, because you do not have to buy batteries, battery enclosure, battery charger, cabling and related equipment.  A grid tied system is less expensive in the long run because the batteries have a limited lifetime and require periodic replacement.  Grid tied systems also have the advantage of gathering and using all the power your solar panels make, because any excess can go back into the grid.  Several of our vendors supply complete grid ties systems, see:  http://www.sunwize.com/products/solar-grid-tie-systems-solar-installers.php  or   http://www.kyocerasolar.com/products/mygen.html

In a stand alone system, the batteries are charged during the middle part of the day, and discharge somewhat at night.  If it will cost as much to bring the power lines to your property as the solar system will cost, then the pay back is immediate, with no power bills in the future.  Several companies make this kind of equipment.  One of the best is Outback, see:

You can also have a hybrid system, that is grid tied with battery backup.  If you live in a area with frequent power outages, this might be a good choice.  The batteries in a hybrid system could be expected to last longer than a stand alone system, because they are not being cycled (charged and dischaged) as much.  If you are considering a stand alone or hybrid system in order to have power during a hurricane, consider that typical golf cart batteries will need to be replaced about every 5 years.  A better choice might be to have a generator, especially a propane powered one (so the fuel does not go bad).

How much does it cost?   That depends on a lot of factors.  Prices of solar modules have come down a bunch in the last few years.  Roughly about $1 per watt for the panels and $1 per watt for everything else.    The federal tax rebate program pays 30% of the total cost, see: http://www.dsireusa.org/library/includes/incentive2.cfm?Incentive_Code=US37F&State=federal&currentpageid=1&ee=1&re=1    The system on our home provides nearly all of our power, not including the air conditioning.  Our system is about 2800 watts.  Our house is very efficient.  Our electric bills (when the A/C is not on, or used very little) less than $20.  A good way to calculate how much power you will get is available from the National Renewable Energy Laboratory: http://rredc.nrel.gov/solar/codes_algs/PVWATTS/version1/US/Florida/ .

A great source of information is HomePower Magazine.  see: www.homepower.com

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