2. Suitability
Before starting to design a solar power system it is important to assess whether solar power provides the best solution to the problem at hand. Solar power is best suited to applications where:
- The energy requirement is modest.
- There is no other source of power available or it is unreliable
- There is a good solar resource.
Despite this, there may be other good reasons for using solar power, for instance a concern for either the local or global environment, planning constraints or similar issues.
2.1 Energy requirement
The amount of energy which is required has a direct bearing on the size and cost of any proposed solar power system. The energy requirement can be reduced as discussed in a later chapter, however there are some applications for which solar generated electricity is very rarely suited. These include space heating, cooking, water heating and any other application where a large amount of heat is required. It may be possible to meet some of these requirements by more direct capture of solar energy, such as solar water heating systems or passive solar building design.
There are some applications which easily lend themselves to solar power, such as lighting and computing, but most things will need to be assessed on a case-by-case basis.
2.2 Other power sources
One of the major factors affecting the choice of solar power is the availability of other potential sources of power. These may include such things as gas, diesel, kerosene and firewood. The most important however is mains electricity. If mains electricity is available it is very unlikely that solar power will be economically viable except for very small energy requirements where the standing charge is likely to greatly outweigh the cost of the energy. It may, however, still be considered for environmental or other reasons.
The usefulness of any other source of power is determined by the nature of the energy form required. It isn’t usually sensible to use electricity for heating, as heat is best obtained either directly by solar heating panels or by burning fuel, ideally wood from managed forests as this is a renewable resource. Light is almost certainly better delivered by solar or possibly wind power.
The reasons for choosing a certain fuel may be complex. For example, bottled gas may be a good fuel in a village close to a main road, however in a mountain village the cost of transport may make it impractical.
2.3 Solar resource
The availability of a good solar resource has a strong influence on the cost-effectiveness of a solar power system. A country in equatorial Africa offers great possibilities for solar power, not just because of the lack of other forms of power but also because of the high levels of sunshine throughout the year.
This does not mean, however, that solar power is impractical in countries further from the equator. In some remote parts of Great Britain, for example, the cost of connecting to mains electricity can be prohibitive. In this context solar power can be very competitive for moderate energy requirements.
Ultimately it may be impossible to decide whether or not solar power is suited to a particular application without following the design process. This way an estimate of the likely cost over the life of the project can be produced, which can then be compared with the costs of the alternatives. The capital costs of solar power systems tend to be high, however the running costs are low owing to the lack of any fuel costs and low regular maintenance requirements.