Sharpe Solar - Frequently Asked Questions

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Renewable Energy (RE) may seem puzzling to some people that are not familiar with it. To help we have compiled and answered a dozen of the most frequently asked questions that we commonly hear. We hope this FAQ file is helpful to you.

HOW DO SOLAR CELLS GENERATE ENERGY?
Photovoltaics or PV for short can be thought of as a direct current (DC) generator powered by the sun. When light photons of sufficient energy strike a solar cell, they knock electrons free in the silicon crystal structure forcing them through an external circuit (battery, inverter or direct DC load), and then returning them to the other side of the solar cell to start the process all over again. The voltage output from a single crystalline solar cell is about 0.5V with an amperage output that is directly proportional to the cell’s surface area (approximately 7A for a 6 inch square multi-crystalline solar cell). Typically 30-36 cells are wired in series (+ to -) in each solar module. This produces a solar module with a 12V nominal output (~17V at peak power) that can then be wired in series and/or parallel with other solar modules to form a complete solar array

WILL SOLAR WORK IN MY LOCATION?
Solar is universal and will work virtually anywhere, however some locations are better than others. Irradiance is a measure of the sun's power available at the surface of the earth and
it peaks at about 1000 watts per square meter. With typical crystalline solar cell efficiencies around 14-16%, that means we can expect to generate about 140-160W per square meter of solar cells placed in full sun. Insolation is a measure of the available energy from the sun and is expressed in terms of "full sun hours" (i.e. 4 full sun hours = 4 hours of sunlight at an irradiance level of 1000 watts per square meter). Obviously different parts of the world receive more sunlight than others, so they will have more “full sun hours” per day.

HOW MUCH WILL SOLAR COST FOR A 2000 SQUARE FOOT HOME?
Unfortunately there is no per square foot “average” since the cost of a system actually depends on your daily energy usage and how many full sun hours you receive per day; and if you have other sources of electricity. To accurately size a system to meet your needs, you need to know how much energy you use per day. If your home is connected to the utility grid, simply look at your monthly electric bill. If not, you can fill out the “load evaluation form” (Click Here). Using this information, we can design a system to meet your own specific needs.

WHAT COMPONENTS DO I NEED FOR AN OFF GRID SYSTEM
There are many components that make up a complete solar system, but the 4 main items on a stand-alone system are: solar modules, charge controller(s), battery's) and inverter(s). The solar modules are physically mounted on a mount structure and the DC power they produce is wired through a charge controller before it goes on to the battery bank where it is stored. The two main functions of a charge controller are to prevent the battery from being overcharged and eliminate any reverse current flow from the batteries back to the solar modules at night. The battery bank stores the energy produced by the solar array during the day for use at anytime of the day or night. Batteries come in many sizes and grades, which you can see starting on page 49. The inverter takes the DC energy stored in the battery bank and inverts it to 120 or 240 VAC to run your AC appliances.

Grid Tie In

WHAT COMPONENTS DO I NEED FOR A GRID TIE SYSTEM?
Grid-tie systems are inherently simpler than either grid-tie with battery back-up or stand-alone solar systems. In fact, other than safety disconnects, mounting structure and wiring, a grid-tie system is just solar modules and a grid-tie inverter! Today's sophisticated grid-tie inverters incorporate most of the components needed to convert the direct current from the modules to alternating current, track the maximum power point of the modules to operate the system at peak efficiencies and terminate the grid connection if grid power is interrupted from the utility.