May 152012

Solar energy produced is a function of how many photons from the sun strike your solar cell, and how many of these photons actually get an electron moving to create a current. The number of photons, or amount of sunshine, that strikes your solar cell needs to be determined to see how many cells or solar panels you will need for your solar system. This energy will vary considerably depending on your latitude, the time of year, and cloud cover that your region can expect.

photons from the sunThe two components to incident solar energy that most flat-plate and evacuated tube solar panels can use are: Direct radiation and diffuse radiation. Understand that concentrating panels are not able to benefit from diffuse radiation.

First, direct radiation means that incident energy comes as though it was a beam of straight rays coming from a source. A good example is, clear, dry days, with no dust in the clouds. That is direct, meaning it comes straight from the sun.

dry daysOn cloudy cover days, with rain, humidity, air pollution, or dust in the atmosphere, much of the solar radiation is all scattered, meaning the energy that comes from the sun go in different directions. We call this diffuse radiation, it’s still available solar energy but its rate is smaller. On days like these a rooftop of a home can receive an average of 1000 Btu’s per sq. ft. for that day. On a good day of direct radiation it could double or triple that. It all depends on the location and time of year, diffuse radiation still produces anywhere from 1/4 to 1/2 of what direct radiation will produce.

irradianceHow do we use Solar Insolation to plan the size of your system? If we know how many kilowatts we need to meet the electric requirements of our home, we are now in a position to size our system. If we are building a grid-tie system, you can use the average annual irradiance for your calculation since the objective is to make our payment to your utility company zero for a full year. If we are building a off-grid system, we need to pick the irradiance value for December since we need to produce sufficient power all year.

A radiant floor heating system will work well with solar because it can make use of relatively low temperature hot water that solar systems produce very efficiently. Your radiant floor heating system can accept heat from solar, a masonry heater, or a gas boiler by sharing a heat storage tank.

heating systemMore solar energy is used today for heating swimming pools than for any other single use. There are over one million solar heated pools in the United States alone. There are 40,000 new solar systems being installed every year by pool owners. A solar pool heating system will give you a reliable, low-to-no maintenance heating solution that reduces or eliminates heating costs and will give you a longer swimming season.
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Homemade Swimming Pool Solar Heating System

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