Understanding Solar Electric Power: Facts and Stats
Solar Electric Power, Facts and Stats
by Don Ames
Solar electric panels take energy from the sun and convert the energy into electricity. Once the solar panels are built and installed, the process of converting sun energy to electricity is clean and usually trouble free. The nice part about solar power is the reduction in carbon production from this type of energy transfer. Energy is transferred to electricity without mining or burning coal – without drilling, pumping, and burning natural gas - without throwing millions of gallons of water off a dam, without mining, enriching, and storing radioactive uranium – or without planting thousands of sterile wind generators with turbine blades that are big enough to threaten airplane flight paths. Solar panels provide earth friendly power.
Most Americans do not have a personal relationship with a bunch of solar panels. About all most people really know about solar panels is from pictures in magazines and the short caption written underneath. Perhaps you have additional knowledge from viewing an ad on T.V. that promises solar electric production and then you never have to buy electricity from the evil empire again. Here in America, most of us have not touched a solar panel.
Let me introduce you to a solar array I have regular contact with. This array and I are personal friends, colleagues, we work in the same place, so we a
re buddies.
A solar panel, on the outside, is made of metal and glass. Inside, silicon crystals. The glass is strong enough to walk on and the panel weighs enough that two people work best when moving the panel ( 50 lbs ). The panels are usually mounted on an aluminum frame that is then attached to a roof or stand. The aluminum frame is light, strong, and resists rusting. Once a year, in the spring, the solar panel glass is washed with water and a soft brush.
The electricity that is produced by the panel is direct current (DC). To use the DC electricity in our home, we either need to change our appliances and light bulbs to use direct current ( like a flashlight ) or we need to run the DC current through an inverter and change it to alternating current (AC). Then we can use the AC electrical power by connecting it to our homes electrical panel. The problem with an inverter is the expense and the lack of efficiency. You know, 24 watts DC in and 18 watts AC out, that sort of thing. The inverter on my friendly array is made by PV Powered, it’s a 30 watt inverter and weighs 750 pounds.
When you hear about a country homestead living off the grid, it usually means they have solar panels charging a large bank of batteries that store the DC power until needed – like at night time for lights. It probable also means that they heat their home with a wood burning stove. The electric panels often times do not produce enough power to operate a furnace.
My array has 98 REC brand panels. Each panel is 39″ wide and 65.5 inches long. From their mounting location, they are all connected by wires that end up at the PV Powered 30 Watt inverter. The solar array produces about 23 watts so a few more panels could be added to the system before the inverter would need to be upgraded. It is important to have the inverter sized to the array. Heavier wires leave the inverter and travel to the side of the garage. The wires pass through a shut off panel then through a digital electric meter that keeps track of total kWh produced. From the meter, the wires connect to the electrical panel and th
en to the grid. An agreement was signed with the power company that sets the provisions of this net-metering system.
During the times that the solar array produces more power than needed, the electric meter runs backwards and electricity is fed back into the grid. The electric company does not pay for the electricity that goes back into the grid. Once a year, the amount of electricity that was used is balanced against the amount produced. If more was produced than used, then the excess is donated to the power companies low income weatherization program. Just how much the access power is worth to the low income program in dollars I am not sure.
On this day, the sun is centered in the sky and the temperature is a nice 63 degrees. The display on the front of the inverter indicates the 98 solar panels are producing 8.0 kilowatts of AC power. So how much electricity is 8.0 kilowatts AC. Converting to kilowatt hours, so far this day, my friendly solar array has provided 57.0 kilowatt hours of electricity by 3:14 in the afternoon. Before the sun sets, even more kilowatt hours will be provided. A 1500 square foot home built in 1995 with good insulation levels, a natural gas furnace and gas water heater uses about 40 kWh per day. This solar array would provide far more electricity than the house uses.
Instead of being connected to a house, this solar array is located at an office building where it proudly produces about 60% of the good clean electricity that the building uses.
THE FIRST STEP in researching solar power for your home is to select qualified Solar Contractors to give you proposals on your solar system.
THE SECOND STEP in deciding whether a solar array is appropriate for your home is to use a solar pathfinder to determine the suns path across the area where the solar array will be mounted.
What’s Net-Metering and will I be asked to sign an agreement with my power provider that allows me to get paid for the power I generate?
Here is the corner of a power bill from a small business that has a solar array connected to the grid. You can see the difference the solar power made. In this broadcast, I also point out how to use your power bill to determine how large a solar system you should install.
Hope you’re a little more knowledgeable about solar arrays, solar panels, and inverters and I hope you will have the opportunity to have your very own solar array someday. Thanks for stopping by Detect Energy, come back soon, but I won’t leave the light on for you…Don Ames