This type of off-grid solar electric system consists of PV modules, a solar charge controller, an inverter-charger, batteries and a generator. The generator is used perhaps once a week or once a month, saving fuel costs and wear and tear on the generator. Normally the generator is only switched on when heavy power-consuming loads or three-phase loads need to be powered, such as an X-ray machine in a clinic or welding equipment. The batteries are mainly charged by the PV modules. The inverter-charger can also charge the batteries with electricity from the generator when the generator is on.
Installing this type of system consists of 2 stages:
- First, an inverter-charger and batteries are installed – the batteries are charged by the generator when it is on; however, this means that the generator can be on for long periods of time in order to charge the batteries fully.
- Then, PV modules are installed with a solar charge controller – this means that the batteries will mainly be charged by the PV modules, considerably reducing the amount of time the generator is on.
Solar modules, an inverter-charger and batteries added to a generator electric system. The batteries are charged mainly by the PV modules. This means that the generator needs to be on for much shorter periods of time, for example, only when heavy power-consuming equipment needs to be powered. The PV modules ensure that the batteries are fully charged more often and have longer working lives.
Special switch gear can be used so that only ‘priority loads’ are powered when the generator is off. Priority loads could be lighting, security systems and other essential services. Powering only priority loads from the battery means the inverter-charger and batteries can be smaller (less expensive) and the batteries will have a longer working life. If the batteries become too discharged, because of high power consumption or during periods of low solar irradiation, an automatic start system can switch the generator on to charge the batteries.