When the distance between renewable energy clusters of solar cells, batteries and electrical loads is relatively far (can be hundred kms) and the electrical loads mostly are AC electrical loads, then it is necessary to consider to use AC buss system, which supported by DC to AC
inverters. By utilizing AC buss system, for long distance electrical transmission, the increase of AC voltage can be conducted by using passive transformator, which is common to be used. However, the integration process of several renewable energy autonomy systems is relatively more complex than integration in DC buss system. The problems in AC buss integration are due to more parameters that must be synchronized, such as voltage, frequency and phase. While in DC buss integration, it is only facing voltage synchronization.
In general, AC electrical power transmission is delivered in 3 (three) phases, especially for 3- phase electrical-mechanical motor loads, in order to be more smooth and more efficient in operation. 3-phase system is inherent in electrical generator based on mechanical generator, by arranging the three generator coils in three different locations by 1200 phase angle in the generator. It also happens in the DC to AC inverter 3 phase. The sine generator generates 3 equal sine wave with different phase each of 1200. DC-to-AC 1-phase inverter system is the fundamental to develop 3-phase system. The knowledge of working mechanism of 1-phase system is very helpful to understand 3-phase system.
In this chapter, we will discuss the working mechanism of DC to AC inverter 1-phase system in general. Then it is continued by discussion of the methods to synchronize thus three parameters of AC buss system, i. e: voltage, frequency and phase. In general, the use of DC or AC buss depends on the distance between sources, batteries and loads, also the variances of the loads. The ultimate consideration is energy efficiency and cost effective of the solar cell sytem.