The characteristics of solar energy imply certain advantages with respect to other sources of energy.
Although the characteristics are different in photovoltaic solar installations and solar thermal installations, we will treat the disadvantages globally.
Certain disadvantages of solar energy may imply that a solar installation may be unfeasible. The aspects to consider are the following:
- Energy efficiency is poor compared to other energy sources.
- The economic cost compared to other options.
- Performance is a function of the weather.
- Limitations on solar time.
- Limitations to store the generated energy
Disadvantages related to energy efficiency
To assess energy efficiency, we must take into account the energy and resources consumed to manufacture the elements of an installation.
A disadvantage of solar energy is in the initial cost. A solar panel consumes a large amount of energy to be manufactured. The energy for the manufacture of a solar panel can be greater than the power generated by it throughout its useful life. However, this cost is lower in a solar thermal installation than in a photovoltaic solar energy installation.
Economic cost compared to other sources of energy
Prices are very high compared to other sources of energy. Especially with regard to photovoltaic solar energy.
At the cost level, photovoltaic energy competes with the cost of fossil energy generated by fossil fuels or nuclear energy. The price per kilowatt generated in nuclear energy is much more competitive but this non-renewable source of energy has the disadvantage of safety.
The disadvantage of climate dependence
Solar radiation varies according to the weather. There is a variation in the quantities produced according to the weather situation (rain, snow) that hinder energy forecasting.
The main disadvantage of the climatology is that it does not allow to make very accurate production forecasts in the short term. In addition, this feature can turn solar energy into an unfortunate option in places with a large number of cloudy days.
To solve this problem, an alternative energy source or the use of batteries is required for the days when the weather conditions are not good or at night. The solar thermal installations have a hot water tank where the thermal energy is stored in the form of hot water.
The inconvenience of solar time
The great disadvantage of solar energy is that one of the moments of greatest energy demand is precisely when there is no solar radiation: at night. For this reason, some energy storage system is required.
It is the case that the locations in middle and high latitudes (for example, Finland, Iceland, New Zealand and the south of Argentina and Chile) suffer sudden drops in production during the winter months due to the lower daily availability of energy solar.
In addition to the schedule in which there is solar radiation, it is necessary to take into account the position of the Sun. The performance of the solar panels will improve depending on the inclination of the Sun. Generally, in times of winter the Sun goes very low during the day so that the radiation that is used is smaller.
For all the problems analyzed, an efficient storage system is required. Today there are batteries and other elements to store electrical energy but there is no system to store large amounts of energy that is really efficient.
Batteries are needed in the case of electrical energy generated by photovoltaic panels, while solar thermal energy generated by solar collectors requires the installation of thermally insulated tanks to keep the hot water they contain. Solar radiation allows the temperature of the fluid to rise, which implies an increase in thermal energy. If these tanks get that this temperature does not go down it will mean that the heat energy is not lost either.
In spite of everything, the forms of storage of solar energy are inefficient in comparison, for example, with fossil fuels (coal, oil and natural gas) or hydraulic energy that keeping the water at a certain height maintains its potential energy without losses, practically.