Solar Energy

Solar energy is the energy that is obtained from solar radiation. The sun is the biggest, most abundant source of energy available to humanity. Even taking into account the distance of the earth's orbit around the sun, which is 150 million km, it constantly provides enormous amounts of energy in the form of radiation. This is approximately 15,000 times the amount that the world's population needs for its primary energy requirements on a daily basis. In theory it is possible to provide all the energy that the world requires by constructing solar power stations in deserts covering an area the size of France.

 

Difference between a solar panel and a solar collector

With a solar collector water is heated by means of sunlight whereas with a solar panel or PV module, the sunlight is converted directly into electrical current.

 

PV

PV is the international abbreviation of photovoltaic. This refers to the scientific process in which sunlight is converted into electricity by means of a solar cell.

 

WP

WP (Watt peak) indicates the solar panel's capacity under standard test conditions. This is referred to as STC: 1.000 W/m2 incident radiation, 25 °C panel temperature, AM1.5 light spectrum.

 

KWH

KWH is the abbreviation for kilowatt hour which is a unit of energy. 1 kWh is the equivalent of providing a capacity of 1,000 W over a period of an hour.

 

How much electricity does a panel produce?

This depends among other things on the type of installation that is whether it is stationary or moving, the type of solar cell and the amount of solar radiation. On average, a stationary solar installation that has a capacity of 1 kW peak, that is set up in the Netherlands or Belgium will deliver approximately 850 kWh of electricity per year. A moving installation that tracks the sun will deliver considerably more with the figures rising by approximately 25% in the Netherlands and even up to 40% in Spain.

 

How does a solar installation work?

Solar cells are generally made from silicon. Silicon is a semi-conductive material and one of its properties is that when it is exposed to light the electrons enter a higher energy state which creates a voltage difference between the solar cell's two contacts. Individual solar cells are linked together to form solar panels or PV modules that convert sunlight into electrical voltage. A converter is then used to change this direct current into alternating current which can be used by the power supply network.

 

Will my installation provide power even if the sun isn’t shining?

Solar cells work even when it's cloudy. Clouds only obstruct part of the sunlight and the rest of the radiation is dispersed as diffused light. It could happen that higher yields would be measured on a cloudy day in May than on a dazzling, hot August day. Shadows on the solar panels will reduce the yield considerably so they should be prevented.

Do the modules have to face south all the time?

The modules will give maximum returns if they face south but a minor deviation from this would be no problem and would only reduce capacity slightly.

 

What types of solar cell are there?

The large majority of solar cells that are currently in use are made from crystalline silicon.

Mon crystalline silicon is drawn from a silicon melt in the form of a rod and then sliced into fine wafers. The solar cell is made from one beautiful crystal. In the case of Poly-crystalline silicon the liquid silicon is poured into blocks and then sliced into wafers. The solar cell will then consist of a lot of different small crystals. Poly-crystalline silicon cells are a little cheaper but give lower returns. Thin film cells are made by applying an active photo-voltaic layer to glass or some other substrate. The returns from thin film cells are a lot less than from crystalline cell types but they are noticeably cheaper.

 

What is a solar installation that is connected to the network?

A solar installation that is connected to the network is connected to the public power supply network and the power generated is fed into it. A separate contract for supplying energy may have to be finalized depending on the network connection.

 

What is an autonomous or network independent solar installation?

Autonomous systems can be found in locations where there is no network connection available or where such a connection would be too expensive given the small amount of electricity that is required. A few examples of this are light buoys at sea, streetlamps and lighting for signs.

 

What is a solar panel’s working life?

A solar panel supplier would be expected to give a 20-year guarantee on the solar panels themselves but not on the entire solar panel installation. Some suppliers even offer a 25-year guarantee. The returns decrease over the years but every supplier will guarantee a minimum return. There are suppliers who guarantee that the output of the solar cells will be 95% of their capacity for 10 years and 80% for 25 years. It can therefore be assumed that solar panels will have a working life of at least 25 to 30 years

 

What maintenance do solar panels require?

PV systems are low-maintenance in principle. The panels are kept clean by the rain, providing that they are installed at an angle of at least 10 to 15 degrees. For larger installations it is certainly recommended that the mechanics, whether stationary or moving, and the electrical installation should be checked periodically so that any defects and malfunctions can be quickly rectified.

 

What is the actual energy cost recovery time?

Energy cost recovery time is taken to mean the time that is required for a solar installation to produce the same amount of energy as was used in its manufacture. An average solar installation has an energy cost recovery time of one to four years depending on the type of solar cell. That is fast when you take into account that the working life of an average solar panel is 30 years.

 

Tracking systems

One way to economize on the use of solar panels is by using sun tracking systems. These will ensure that the solar panels are in the ideal position relative to the sun throughout the day.

Because this enables a lot more sunlight to be caught it also means that a lot more electricity can be produced. In the Netherlands this is an increase of approximately 25% and up to 40% in Spain. In addition to this, tracking systems can be used in combination with mirrors to focus sunlight on a solar cell or special towers to produce electricity.

 

What is the reduction in CO2 emissions?

Using solar panels reduces CO2 emissions considerably. A 1 MW solar tracker in the Netherlands achieves a reduction in CO2 emissions of 600,000 kg per year. Which over 20 years amounts to 12 kilotons! In comparison, an average car emits 2,400 kilograms per year and a tree absorbs approximately 1.2 kilograms of CO2 per year. This is the equivalent of 10 million trees or 80 hectares of forest in Europe for the 1MW installation.

 

Is sustainable energy being promoted?

A lot of countries have an active policy regarding sustainable energy and reducing CO2 emissions. The Dutch authorities have set the target of having 20% of energy production in the Netherlands being produced from sustainable sources by 2020. Each country, and sometimes this even depends on the region, has its own measures for stimulating the production of sustainable energy. There are investment allowances and subsidies for the kWh that are generated. In the Netherlands this includes the SDE and EIA regulations