Solar Power

   Solar cells (also called photovoltaic cells) are electrical devices that convert the energy of sunlight directly into electricity by the so-called photovoltaic effect. They do not contain moving and turning parts. Their lifespan can be measured in decades. They are applied for independent power source or reducing the cost of electricity bills. They are also used for developing secondary power source. Different materials display different efficiencies and have characteristics matched to the spectrum of available light. Solar cells made of amorphous silicon material absorb blue light more efficiently while monocrystalline and polycrystalline silicon cells make the red spectrum light use.
   Presently there are various solar cells on the market; basically we distinguish 4 types of them:

Amorphous solar cell

   The most widely spread solar cell due to low manufacturing cost. Its efficiency is 4-6 %, which is the lowest comparing to the other types. In compensation of the poor efficiency it needs larger surface and so place for installation. Amorphous solar cells make scattered light use better than direct sunlight. Its lifespan is around 10 years.

Monocrystalline solar cell

   The most efficient solar cell used today with an efficiency of 15-17%. It makes direct sunlight use better than scattered light. Its lifespan is around 30 years.


Polycrystalline solar cell

   This type of solar cells has an efficiency of 10-13 %. Its lifespan is around 25 years.

Thin film solar cell

   For a shorter and easier pronounced form the device is commonly called „thin solar cell”. Efficiency is close to (moreover, some outstrips) the values of polycrystalline cells. The average efficiency is presently 8-10 %; the lowest is 5 % and the peak may mount up to 15 %. As a whole, thin solar cell can be featured of being able to produce nominal power not only by optimal designated angle (in Hungary it is 45°) but also by a 15% difference. Thus solar cells can be installed in the angle domain of 30 – 60°. In opposition to the traditional ones thin solar cells can convert even scattered sunlight into electrical power at a certain level.

Solar power systems can be constructed as follows:


Off-grid system: Solar cells + batteries (accumulators) + inverter = 230 V. Batteries add some extra cost, but in exchange provides independency.
   Grid-tied system: Solar cells + feedback inverter + separate meter. The generated, unused excess power is delivered back to the grid. The meter either stops or reverses. The power delivered back to the utility company can be used to offset utility bills. Operational cost should be lower as no batteries needed but the more specific devices and authorizations take expenses. Dependency is the only disadvantage of the system.