It is now easier than ever to provide power to your home through one of the cleanest sources of energy available.
Solar power is power obtained from the energy of the sun’s rays that can be used for electrical (power) or thermal (heating) purposes. It can be used actively or passively and is one of the cleanest and quietest sources of energy available without producing pollutants or noise.
Solar power is a renewable resource, meaning that it is replenished over time and essentially should never run out. The sun is expected to be around for at least another 5 billion years, but just how much energy does it generate for us? The earth receives about 8.2 million “quads” of Btu energy per year of solar energy. In relation, the entire world consumes about 400 quads of energy total per year. To put in perspective - the amount of solar energy that hits the earth is over 20,000 times greater than the amount of energy used by mankind (see more at How Much Solar Energy Hits the Earth). The sun is fully capable of fulfilling our power needs for a very long time, but the tricky part is being able to harness the energy and efficiently use it in a cost-effective manner. Advances in science and technology, along with research and incentives are making solar energy a more accessible form of power for homes and businesses.
History of Solar
The sun’s energy has been used as a power source since 7th century B.C. when magnifying glasses were used to help start fires. For thousands of centuries, people have been using passive solar energy (using sunlight directly for lighting and heating purposes) in order to light and heat their homes and buildings. Ancient Romans through today place many windows on the south side of buildings to take full advantage of nature’s light and heat. Principles of solar energy have been used essentially since the beginning of time, but it wasn’t until the 1800s that solar energy transformed into a more sophisticated source of energy.
Looking for a deeper dive into the history of solar power? Visit the Department of Energy for an in-depth solar timeline.
Solar energy is more accessible than ever and continues to increase in efficiency and decrease in cost. There are three main forms of active solar - Concentrating Solar Power (CSP), Photovoltaic (PV), and Solar Heating and Cooling (SHC).
There are four different CSP system configurations - parabolic trough, linear fresnel, power tower, and dish engine. Each system has a different way of focusing sunlight, but all use similar components, like collectors, receivers, and thermal storage.
For more information on CSP plants, check out: SEIA - Solar Energy Industries Association.
Photo courtesy of NREL/DOE- Greg Glatzmaier/ NREL 19807 at Gemasolar Plant owned by Torresol Energy.
Photovoltaic cells, also known as solar cells, are composed of semiconductor materials (silicon is most common). Semiconductors have molecular structures that are beneficial to generating electricity. The atoms of the material have electrons that can easily be knocked out of place, which generates electricity. When light hits the cell, a certain amount of it is absorbed into the semiconductor material. This energy knocks those previously mentioned electrons loose, allowing them to move freely, which creates a flow of electrons. This flow of electrons is the electrical current that travels through wires and electrical circuits. PV cells vary widely in terms of size and capacity to supply power - all the way from your calculator to large buildings with equally large energy needs.
PV cells are often connected together to form PV modules, which can supply more energy than a single cell. Modules can also be connected to form even larger units that generate even more power called arrays. The ability to change the power level through the amount of cells allows solar technology to satisfy a large range of power needs.
PV systems are made up of multiple cells, modules, or arrays and include balance of system (BOS) components. BOS components include structures that point the cells toward the sun, components that condition the electricity produced, and may also include batteries.
PV systems can be set up in many different ways or places as long as they are stable, durable, and can withstand severe weather. Different set ups include solar panel roof mounts, ground mounts, pole mounts, and even carport mounts. Structures can either be stationary or tracking. Stationary mounting structures take into account the latitude of the site, sunlight availability, and load requirements, which means the PV array is tilted at a fixed angle based upon those items. One type of stationary mounting structure called rack mounting can be installed on either slanted roofs or on the ground, making it very versatile. Tracking structures, on the other hand, have two basic types: one-axis and two-axis. One-axis trackers usually track the sun from east to west, where two-axis types track the sun’s seasonal course between the northern and southern hemispheres, along with its daily east to west movement. Two-axis tracking systems tend to be more expensive and require more maintenance.
Photovoltaic cells produce direct current (DC) power, but most appliances and electronics require alternating current (AC) power. In order to use the DC, a PV system requires a conditioner. Power conditioners process the electricity produced by the system and make sure it is compatible with the specific demands of the load. These power conditioners can also match the converted AC to a utility’s electrical network, and have safeguards to protect both personnel and the network from any harm during repairs.
On occasion, it may not be possible to generate power through the PV system (i.e. clouds, poor weather, or nighttime). However, electricity is still needed, so it must either be stored or come from another means. Many PV systems are also connected to the power grid. When the PV system is not generating electricity for any reason, power is supplied through the grid. As an added bonus, when the PV system is generating more power than needed, the excess power can be transferred to the grid. There is a monthly fee to be connected to the grid, even if your system's production offsets the costs. In the case of a power outage, a home equipped with solar will also lose its power. Using a battery backup system is a way to store energy when being connected to the grid is not an option or is not desired. The system will be completely independent and will remain powered even if the grid goes out. However, only about 80% of the energy that enters a battery can be reclaimed, which lowers the efficiency of the system. They are also large and require periodic maintenance.
There are multiple photovoltaic cell technologies being used and in development today, including PV solar shingles and PV thin film.
|PV Solar Shingles|
|PV Thin Film (Photos courtesy of DOE/NREL)|
Solar water heaters use the sun’s thermal energy to heat water.
Solar energy can be used for cooling too, whether it is a cooling system that primarily uses a PV system to run, or through solar-powered absorption chillers. Some air conditioning units are designed specifically to run primarily on solar energy.
For more information on Solar Heating and Cooling, check out: SEIA - Solar Energy Industries Association.
Pros and Cons of Solar Technology
|One of the cleanest sources of energy||Cannot be used at night; not as effective on cloudy or stormy days|
|No pollutants; Quiet||Will not operate during a blackout unless connected to a battery backup|
|20+ year life expectancy||Not suitable for all locations|
Frequently Asked Questions
The most suitable location for a roof-mounted Solar PV System is a south-facing roof with little to no shading from nearby trees, chimneys or other obstructions. Any shading on the system can reduce energy output. With new panel and inverter technologies, homes with east or west-facing roofs and moderate shading can benefit from solar voltaic energy as well.
Yes, just not as much. Under an overcast sky, panels will generate less electricity than they produce on a clear, sunny day.
- The Smart-E Loan allows you to go solar for no money down with flexible terms from 5 to 12 years and rates as low as 4.49% and no repayment penalties. Bundle solar with additional upgrades and save even more with rates as low as 2.99. You can finance over 40 energy upgrades that generate clean energy or reduce your home’s fuel or electricity use.
Solar power is listed as a Class I renewable energy source as defined in the Connecticut General Statutes (CGS) Section 16-1(a)(26)(i).
If you are interested in adding solar technology to your home or business, you have many options.
- Residential Solar Investment Program
- Smart-E Loan
- Solarize Connecticut
- Go Solar CT
- Sun Shot
- Residential Solar Hot Water