Sun is an infinitely renewable resource of energy. Solar energy technology makes use of sun's radiation to generate heat or electricity. The process used to convert sun’s radiation into electricity is called the Solar PhotoVoltaic (PV) Effect. The process used to convert sun’s radiation into heat is called the Solar Thermal Effect. The generated heat can be used for heating or generation of electricity. Solar Energy Technology is therefore divided into two broad categories, PhotoVoltaic (PV) Technology and Solar Thermal Technology. We deal exclusively in PV Technology.
Solar Cells (also known as PV Cells) use Photons from the sun’s rays to generate electricity through the photovoltaic effect. There are several types of solar cells. A typical wafer-based crystalline silicon solar cell is 0.2mm thick and 6 inch square (150mm square) and rated at 3.75W DC (7.5A at 0.5V) under standard test conditions (STC). STC is a controlled test environment ensuring irradiance of 1000 Watt/meter2, 25 oC, and spectrum of AM 1.5.
Solar Panel (also known as PV Panels or Solar Modules or PV Modules) is an assembly of solar cells. The assembly is encapsulated under heat and vacuum between a tempered glass cover on the top and a protective PVF cover at the bottom. This process makes solar cells immune to weathering for 25 years or more. An anodized aluminum frame is attached for further protection and ease of mounting. A solar panel typically has a terminal box attached to the back where electrical connections are made.
Solar panel can be as small as 10W and as large as 400W or larger. A typical solar panel consisting of 60 series connected solar cells can be rated at 225W DC (7.5A, 30V). Typically, a solar panel made of crystalline solar cells with a power rating in the 200W to 250W range under STC, is 1 meter x 1.6 meter x 40mm in size, and weighs 20Kg.
This depends on several factors, some of them are: solar resource and temperature in the area of installation, angle of solar panel mount, time of the year, and efficiency of solar panels, inverters, and charge controllers. Electricity production per year is called Annual Energy Yield. It is determined by simulating hourly system performance throughout the year using specialized solar software. We estimate annual energy yield in the range of 1400KWh to 1800KWh per KW of installed capacity for solar installations in Pakistan.
Worldwide pricing of large-scale fully installed on-grid solar systems presently has a range of USD 2,000 to USD 3,000 per KW. Prices for smaller systems or systems with battery storage have a higher range. Prices in individual countries vary by taxes, duties, regulations, compliance requirements, and prevailing business conditions.
Most of the space in a solar system is taken up by solar panels which require roughly 10m2 of outdoor space per KW of installed capacity. In a battery backup system, additional indoor space is required for the battery bank. The control electronics require relatively small amount of space.
The longevity varies by the system component. Solar panels typically last 25 years, electronic components last longer than 5 years, and flooded deep cycle batteries (not GEL and AGM) last 5 to 10 years depending on their construction and depth of daily discharge.
On-grid solar systems are made of an array of solar panels connected in a series and parallel combination and one or more on-grid inverters to convert DC electricity generated by solar panels into AC. The inverter has built in features to synchronize to the electricity supplied by the grid. These systems can range from 1KW to 100s of MW. Typically no electricity storage is provided since it is assumed that the utility supply is reliable, the electricity produced during the day is used within the facility and the excess is sold to the utility via the grid connection, and at night when no solar electricity is generated electricity from the grid is used in the facility.
Off-Grid solar systems are made of an array of solar panels connected in series and parallel combination, one or more off-grid inverters (to converter DC electricity generated by solar panels into AC), a bank of deep cycle batteries, and one or more battery charge controllers. These systems are suitable for areas where there is no grid available.
Off-Grid DC Systems are typically in the range of 50W to 250W. These systems are made of one solar panel, one battery charge controller, and one deep cycle battery. Since these are usually DC systems, consumers can use only use DC loads such as DC light, DC fan, and DC television.
Hybrid Solar Systems work on both solar and grid electricity. During daytime, the loads are operated by solar energy. During nighttime, they are operated using the energy stored in solar batteries or on grid electricity. These systems are most suitable for locations where grid is present but is unreliable (load shedding). Hybrid system consists of an array of solar panels connected in a series and parallel combination, one or more charge controllers, a deep cycle battery bank, and hybrid inverters.