Powering pumps for crop irrigation or stock watering and pumps or blowers for solar heaters are some common load direct applications. Recent innovations include the National Park Service using P.V. powered blowers with solar air collectors in back country self-composting toilets. P.V. direct systems are simple, lower in cost and virtually maintenance free. DIagram of AC System. If an application needs power available at night, lighting for example, batteries and a charge control are necessary to store the electricity.
Charge controls keep batteries from damage through overvoltage.
The charge control cuts the power to the batteries when full charge is achieved. It is a must on all systems except ones with very large battery banks and small P.V. charging capacity. If the battery storage capacity is more than fifty times the P.V. daily output a charge control is not necessary. Batteries used with photovoltaic modules are called deep cycle. Deep cycle batteries are manufactured to be able to discharge most of their stored energy hundreds of times without damage.