Solar Photovoltaic
- Tania Hattingh
- May 1, 2018
- 3 min read
"Solar is cost effective right now. When you consider the cost to our health from air pollution, solar is just as competitive as any other energy source." — Thomas P. Kay
Photovoltaics (PV) is a method of generating electrical power by converting solar radiation into direct current electricity using semiconductors that exhibit the photovoltaic effect. Photovoltaic power generation employs solar panels composed of a number of solar cells containing a photovoltaic material.
Materials presently used for photovoltaics include monocrystalline silicon, polycrystalline silicon,amorphous silicon, cadmium telluride, and copper indium gallium selenide/sulfide.
Due to the growing demand for renewable energy sources, the manufacturing of solar cells and photovoltaic arrays has advanced considerably in recent years.
Solar photovoltaics have long been argued to be a sustainable energy source. By the end of 2011, a total of 67.4 GW had been installed, sufficient to generate 85 TWh/year.
Solar photovoltaics is now, after hydro and wind power, the third most important renewable energy source in terms of globally installed capacity.
More than 100 countries use solar PV. Installations may be ground-mounted (and sometimes integrated with farming and grazing) or built into the roof or walls of a building (either building-integrated photovoltaics or simply rooftop).
Driven by advances in technology and increases in manufacturing scale and sophistication, the cost of photovoltaics has declined steadily since the first solar cells were manufactured and the levelised cost of electricity (LCOE) from PV is competitive with conventional electricity sources in an expanding list of geographic regions.
Net metering and financial incentives, such as preferential feed-in tariffs for solar-generated electricity, have supported solar PV installations in many countries. With current technology, photovoltaics recoup the energy needed to manufacture them in 1 to 4 years
How Solar Works
The science is very complex, but the concept is simple. It’s a multifaceted system that makes the sun’s energy available through a building’s electrical infrastructure and it is our key to a greener future!
Solar power systems are complex structures that convert the sun’s energy into electrical power. Photovoltaic (PV) cells are the driving force behind the operation. They convert the sun’s energy into electricity. When sunlight hits the photovoltaic cell, it produces an electrical current. Photovoltaic cells are connected and held together in a solar module.
Solar panels are groups of solar modules (which contain the PV cells) and they are installed in open areas, like rooftops or fields, to receive sun exposure. When sunlight falls onto these panels, direct current electricity (DC) is instantly created.
That electricity then passes through a wire channel leading to an inverter which transforms it into alternating current electricity (AC), which is the form of electricity we ordinarily use. Now the electricity can be used to power your lights, appliances, air-conditioning, computers and other electrical devices!
Not too perplexing, right?
Solar energy is the way of the future. We want to reduce our dependence on costly fossil fuels; therefore we are shifting to a highly reliable, long-term, and fixed price electricity supply.
PWM and MPPT charge controllers are both widely used to charge batteries with solar power.
The PWM controller is in essence a switch that connects a solar array to the battery. The result is that the voltage of the array will be pulled down to near that of the battery.
The MPPT controller is more sophisticated (and more expensive): it will adjust its input voltage to harvest the maximum power from the solar array and then transform this power to supply the varying voltage requirement of the battery plus load. Thus, it essentially decouples the array and battery voltages so that there can be, for example, a 12 volt battery on one side of the MPPT charge controller and panels wired in series to produce 36 volts on the other.
It is generally accepted that MPPT will outperform PWM in a cold to temperate climate, while both controllers will show approximately the same performance in a subtropical to tropical climate.
Article by Thomas P. Kay
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