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Standalone Solar Systems

As you probably know solar energy from standalone solar system is clean and eco-environmental friendly renewable energy source. It has a low energy density, most suitable from conservation of eco-system point of view. But how is it all made of and how exactly does it work?

Components of a standalone solar system...

Solar modules are only a small part of a standalone solar system. They work together with other components: batteries, inverters, and transformers. Together with power distribution panels and metering devices they complete the process.

STORAGE BATTERIES
As mentioned in our previous articles solar panels are devices that only convert solar energy into a DC voltage. Solar panels don’t store energy, to store solar energy once the sun stops shinning; the DC voltage is used to charge a set of storage batteries. Amount of batteries needed varies according to the requirements of the application that will be powered by your standalone solar system. The amount of required batteries depends on the application. Circuit loads, such as telecommunications and remote telemetry stations, may require 2 weeks worth of battery power while standalone solar systems require no more than 12 hours. Batteries must be properly selected to store sufficient energy for the daily demand. When considering what battery storage capacity additional factors must be taken into account, such as cloudy and sunless days.. In addition to batteries, charge regulators must be used to cope with fluctuation in the DC power produced by solar panels. Charge regulators are placed between solar panels and storage batteries to prevent them from over-charging.

INVERTERS
As described earlier, solar panels generate DC current, which can be used by only a limited number of devices. Most residential, commercial, and industrial devices and appliances are designed to work with alternating current or AC. And that’s why we need inverters. Inverters are devices that convert direct current into alternating current or AC. Although inverters usually are designed for specific applications, the basic conversion principles remain the same. Essentially, the inversion process consists of the following: DC current is essentially chopped into equidistant segments that are then processed through circuitry that alternately eliminates positive and negative portions of the chopped pattern, which results in a waveform pattern called a square wave. Some manufacturers today offer devices with high-frequency transformers instead, thus strongly reducing weight at the cost of efficiency. In countries where grounding of the PV generator is not mandatory, transformer less inverters are increasingly introduced. They are lighter and more efficient, but particular care has to be taken on EMC and fault current detection. The serial production of PV inverters was launched in the 1990’s. Before that time, only a small number of inverters were needed, mostly for standalone applications, for example, for residential PV systems. Because there was no connection to the public grid, the standalone of power quality in system was not as important as it has to be if power is sent back into the power grid.