Solar energy facts

Information to Know About Solar Energy

  1. Renewable energy is energy which comes from natural resources such as sunlight. It is one of the most abundant resources on earth. In fact, 173,000 terawatts of solar energy strikes the earth continuously. That’s more than 10,000 times the world’s total energy use. So it is safe to say that the sun’s energy is in abundance and it is free to harness.

2. Solar energy (photons) is comprised of both radiant heat and light and can be utilized through the use of photovoltaic technologies (solar panels) that take advantage of the sun’s light energy and its heat energy which is captured by solar heat collectors to heat buildings, water, etc.

3. One of the main benefits of solar energy is that it is a clean source of energy and it is renewable. Solar panels, once installed, requires low maintenance. One limitation to solar panel generated energy is that it cannot be used at night and are affected by weather conditions, location, time of day and time of year. 

4. Photovoltaic panels and solar thermal collectors are considered to be active solar technologies. 

5. Solar power can significantly reduce electricity bills. In most cases, solar generated electricity does not cover total demand. There will still be a need for a public utility provider. In fact, these solar systems, in most cases, are tied into a public utility provider through a net metering contract. Net metering is defined as a system in which solar panels or other renewable energy generators are connected to a public-utility power grid and surplus power is transferred onto the grid, allowing customers to offset the cost of power drawn from the utility.

6. A solar panel system consists of several solar panels, an inverter, wiring and support materials. Solar panels can be roof mounted or ground mounted. Sunlight is absorbed by the solar panels and is converted to electricity by the installed system. Storage batteries can also be integrated into the solar system. By utilizing batteries, solar energy can provide around the clock electricity even at night or on cloudy days. 

7. There are Federal tax incentives and in some cases, a public utility rebate program to help defray the costs of installation for both businesses and home owners. Any good solar energy system installer, like Heartland Alternative Energy, will let you know what is available.

8. Solar Energy is measured in kilowatt-hours. A kilowatt hour is simply one kilowatt of energy being consumed for one hour. An average home electrical usage is approximately 10,950 kilowatt hours per year (kWh/Year).

In Case You Want to Know More…

There are different types of photovoltaic cells:

Mono-crystalline cells:

1. Silicon based – extracted from sand.

2. Extracted from melted silicon.

3. Allowed to cool forming large rods that are sawed into thin plates.

4. More pure, more costly, and a labor intensive process guaranteeing a relatively high level of silicon cell efficiency per square meter.

5. Because they have a higher power output per square meter, they are ideal when space is limited.

6. Using all available roof space with mono-crystalline cells will generate more energy than poly-crystalline cells.

Poly-crystalline cells:

1. More expedient and cost-efficient. 

2. Made when liquid silicon is poured into blocks and sawed into thin plates.

3. During the solidification of the material, crystal structures of varying sizes are formed.

4. Defects along the borders of the blocks can emerge which produces a less efficient solar cell. 

5. During the solidification of the material, crystal structures of varying sizes are formed.

6. Defects along the borders of the blocks can emerge which produces a less efficient solar cell.

 Amorphous cells:

1. The silicon film is deposited on glass or another substrate material resulting in a  so-called amorphous or thin-layer cell. 

2. The layer thickness amounts to < 1µm – the thickness of a human hair for  comparison is 50-100 µm. 

3. Production costs of this type are lower because of the lower material costs.

4. The efficiency of amorphous cells is much lower than that of the other two cell types.

5. These cells are mainly used in low power equipment such as watches and pocket calculators. 

What is Insolation?

  1. Insolation (Incoming Solar Radiation) is the amount of solar      radiation incident on any surface i.e. Earth’s surface, Solar cells. The      amount of solar energy that strikes a square meter of the earth's surface      in a single day. The values of solar insolation are commonly      expressed in kWh/m²/day. 
  2. Insolation on the surface of the Earth is controlled by the:
    1. Angle of the sun 
    2. State of the atmosphere 
    3. Altitude / Latitude
    4. Geographic location

Basic Electrical and Solar Cell Terminology

1. Direct Current (DC) Is a steady stream of electrons traveling along a conductor from one place to another.

2. Alternating Current (AC) is an electrical current that reverses its direction of flow several times per second. (60 cycles/sec or hertz in US)

3. Amperage (Amps) is the volume (or quantity) of electrical current flowing through a circuit.

4. Circuit is a complete path for electrical current flowing from the building power source to the equipment being powered and back to the power source.

5. Voltage (Volts) is the measure of electrical pressure in a circuit. One volt of pressure is required to push one amp of current through a conductor with one ohm of resistance.

6. Ohm is the measure of electrical resistance, or impedance, in a circuit. One volt will cause one amp to flow through one ohm of resistance.

7. Inverter is a device that will convert the DC current from a solar array into AC current.

8. Wattage (Watts) is the amount of power used by an electrical device. It is also the basic measure of electricity.

9. Calculating the cost of electricity:

Wattage x Hours Used ÷ 1,000* x cost per kWh = Cost of Electricity

* (Dividing by 1,000 changes the calculation from watt-hours to kilowatt-hours.) 

Learn More

View a couple of short videos that explain:

1. How solar panels work.

2. How net-metering works.