The energy emitted by the Sun and reaching the Earth is the radiation energy produced by the fusion reactions at the core of the Sun. It is caused by fusion reactions that convert hydrogen gas in the Sun into helium. Radiation intensity outside the Earth’s atmosphere is around 1370 W/m2, but it varies between 0 to 1100 W/m2 on Earth. Even a fraction of this energy traveling to the Earth is many times more than the current energy consumption of the human kind.
Studies on how to make use of solar energy have gained momentum after the 1970s, solar energy systems have developed technologically and their cost reduced, and solar energy has established itself as an eco-friendly and clean source of energy.
The performance of a solar cell is measured by its efficiency. The most important parameter that determines the efficiency is the percentage of received energy that is converted to available electricity. However, light only at certain wavelengths can be converted into electricity, the rest is either absorbed or reflected by the substance that makes up the cell. Therefore today, the efficiency of a typical solar cell is around 15%, meaning that it only converts one sixth of the energy it receives.
It is possible to achieve maximum efficiency from solar panels in every season by directing them towards the Sun at various angles. A 60 degree tilt that is generally employed across Turkey and properties of solar panel glasses help prevent frosting and snow accumulation. Alternative energy systems can be designed on-grid, off-grid, or as green-line in line with project requirements.
The power of green-line solar cell systems range from a few kW to a few MW. Such systems can be high-power plant-sized systems and can also be used as small-power systems in buildings, which is the more common application.
Green line systems are usually preferred where there is no grid available. As long as the climate data provided is sufficient, these systems are more profitable than the investment needed to connect to the grid when even only the initial investment cost is considered.
A battery is necessary in these systems so that the generated power can be stored and used at night or when there is no power generation. The battery capacity is determined based on the climate data of the region, electrical devices to be used and the duration of use.
Fields of use of green line systems can be listed as follows:
- Communication stations, rural radio and telephone systems
• Cathodic protection of petroleum pipelines
• Protection of metal structures from corrosion (bridges, towers, etc.)
• Telemetric measurements in electricity and water distribution systems, air observation stations
• Indoor and outdoor lighting
• Operation of electrical devices such as the TV, radio and refrigerator at mountain or remote houses
• Water pumping for agricultural irrigation or for domestic use
• Forest observation towers
• First aid, warning and security systems
• Earthquake and air monitoring stations
• Mountain houses, farms
• Special applications such as boats and RVs.
Turkey’s average annual total duration of sunshine is 2640 hours (total 7.2 hours per day), while the average annual solar radiation is 1311 kWh/m2 (total 3.6 kWh/ m2 per day). As it is evident from the figures, Turkey should start focusing more on alternative energy sources without any delay.