Photovoltaic modules transform solar energy into DC current which may be used to supply electrical devices (either directly or via an inverter which transforms the DC voltage to an AC voltage). The DC energy is stored in a storage battery. The storage facility is controlled by a regulation system, which also protects the battery. 

Solar pump systems provide an ideal self-sufficient solution for use in water supply installations. The low maintenance and low supply costs of stand alone systems makes them ideal for supplying rural populations (no diesel required for generators etc.) stand alone systems are also available for supplying street lighting, signaling devices etc. in villages and towns.

Profitability

There is a large demand for economically sustainable energy supply solutions in Bangladesh. However, solar electricity supply systems require a higher initial investment cost when compared with standard diesel generators. This often makes potential buyers tentative. The initial investment costs for photovoltaic systems are 5 to 10 times higher. This does not consider the running costs of a diesel generator supply: the running costs will rapidly increase through continuous use 365 days/24 hrs with the need for a complete overhaul every 12 months. The potential costs become even greater when taking into account increasing oil prices and transportation costs to remote regions. Inadequate infrastructure and logistics also have a negative effect on generator maintenance.

The maintenance effort for PV systems is comparatively low. The following example assumes that the batteries will need replacing after 10 years. When making a direct comparison, the solar solution is already more economic than a comparable diesel generator after 7 years. Given that the investment period is 20 years, the diesel option will ultimately be twice as expensive as an independent solar installation.

Quality benefits

	No fuel costs
	Low maintenance costs
	Reliable power supply for telecom stations
	Independence from oil price fluctuations and increases
	No environmental pollution caused by noise, emissions and oil leakages
	Technically extremely reliable using long life components (no wearing parts)