adminThis is the first in a four-part series on solar power and thermal systems. Every day the sun provides a huge amount of light and thermal energy. This energy is fully renewable, free and available for an average of six hours per day. In Zimbabwe, we have an abundance of good quality sunshine throughout most of the year and this energy from the sun can be converted into electrical energy by photovoltaic solar panels for power and into thermal energy by heat collectors for hot water.
Basic solar power system
The energy from the sun arrives at the earth’s surface and this energy is collected by solar panels or photovoltaic panels (PV panels) and converted to electrical energy.
Solar panels are the core to a solar power system and are made from silicon; the newer and more advanced panels are either mono or polycrystalline (bluish in colour) and have warranties of 20-25 years to 80-90 percent efficiency.
They convert the radiation/light energy into Direct Current electricity, without any moving parts, noise or emissions. The DC electricity generated by the solar panels is then stored in batteries or accumulators, these store the power until such time as it is required. The stored power can be used as direct current or is converted via an inverter into Alternating Current the same as supplied by a normal power grid.
Batteries can be arranged in systems, ranging from 12V, 24V, 48V or even larger and this will depend on the size of the required system, batteries for solar must be deep cycle and ideally maintenance free or sealed.
The power generated by the solar panels is controlled by a charge controller, which carries out various functions such as protecting batteries from overcharging and complete discharge, protect panels from feedback from batteries and monitors state of batteries, panels, temperature and appliances.
The DC power stored in the batteries is converted to AC power by means of an inverter; this is done by a transformer and various circuits. The power is converted to 220V AC power for use by most appliances and electrical equipment.
Basic solar geyser
The thermal energy from the sun arrives and is absorbed by heat collectors and converted to hot water, heat collectors can be very basic — black piping laid in the sun; flat plate collectors with copper tubes in glass boxes and evacuated tubes, etc.
Heat collectors must be mounted in the sun and ideally face north to maximise efficiency, the evacuated tubes are the latest technology and have extremely efficient thermal energy to heat transfer.
The hot water produced by the heat collectors is then stored in an insulated tank. The tanks normally have a stainless steel inner lining with 50mm of insulation and a gal-vanised outer lining.
Most solar geysers have an optional extra electrical back-up for times of inclement weather or heavy use of the hot water and this consists of an electrical element and controller.
Fore more information contact [email protected] or visit our website www.vondexsolar.com
Online Reporter