The solar coverage rate is the percentage of an amount of

energy Energy () is the physical quantity, quantitative physical property, property that is transferred to a physical body, body or to a physical system, recognizable in the performance of Work (thermodynamics), work and in the form of heat and l ...

that is provided by the sun. This may be in reference to a solar thermal installation or a photovoltaic installation, i.e. a calculation of solar heat,

electricity Electricity is the set of physical phenomena associated with the presence and motion of matter possessing an electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by Maxwel ...

or total energy produced. The observation period is typically one year. As a general rule, higher values represent improved energy efficiency and improved environmental outcomes.

General

The solar coverage rate is used for need-based planning of solar installations and is a measure of the energetic (non-)dependence on

energy sources Energy development is the field of activities focused on obtaining sources of energy from Natural resource, natural resources. These activities include the production of Renewable energy, renewable, nuclear power, nuclear, and fossil fuel derive ...

other than the sun. Differentiation between solar coverage rate for buildings for: *

water heating Water heating is a heat transfer process that uses an energy source to heat water above its initial temperature. Typical domestic uses of hot water include cooking, cleaning, bathing, and space heating. In industry, hot water and water heated t ...

, * room heating, * required overall heating, *

electricity generation Electricity generation is the process of generating electric power from sources of primary energy. For electric utility, utilities in the electric power industry, it is the stage prior to its Electricity delivery, delivery (Electric power transm ...

, * required total energy. This value depends on the size of the storage unit ( hot water tank or

storage battery A rechargeable battery, storage battery, or secondary cell (formally a type of energy accumulator), is a type of electrical battery which can be charged, discharged into a load, and recharged many times, as opposed to a disposable or prim ...

), the size of the harvesting surface (sun collection surface or surface area of photovoltaic modules), and on the amount of energy required. In addition to the total yield, there is another dimension that is important for assessing the effectiveness of a solar facility. This is the total energy loss and storage loss suffered by the facility.

Cost effectiveness

The solar coverage rate cannot be used as the only measure of the

cost effectiveness Cost-effectiveness analysis (CEA) is a form of economic analysis that compares the relative costs and outcomes (effects) of different courses of action. Cost-effectiveness analysis is distinct from cost–benefit analysis, which assigns a monetar ...

or quality of a facility. Other conditions must be taken into account. Among other factors, the value depends on the size of the facility, the location and orientation of the collectors, the size of storage available and the amount of energy required. A solar coverage rate of 100% would mean that the system's entire energy requirement can be covered by solar energy. For a solar thermal facility in Europe, this would mean that the entire heat requirement could be covered, even on a cold winter's day. On summer days, however, this same facility would produce a very large surplus that could not be used. The facility would have to be heavily over-dimensioned for the summer and could not necessarily be operated economically. A high level of coverage is therefore not always an advantage. Nevertheless, if very high coverage levels are to be achieved, then solutions can be offered in a local heat network. When planning a solar thermal facility, the optimal goal is to find a balanced compromise between yield, i.e. heat energy provided, and the solar coverage rate. A good compromise between yield and solar coverage usually also represents a good compromise between investment costs for the solar facility and costs saved on conventional energy.

References

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