Off-Grid Photovoltaic (PV) and Water Pumping

Solar electric, or photovoltaic (PV), systems convert sunlight directly to electricity. They can power an electrical appliance directly, or store solar energy in a battery. An off-grid PV system, commonly referred to as a stand-alone system, is designed to produce electricity for a home, business, or farm, without any supplemental power from the utility or electric distribution grid. An off-grid PV system consist of a PV array, controls, safety equipment, and inverter (to convert DC power to AC), and a battery system or bank to store power. The battery bank is essential because they store electricity that can be used when the sun is not shinning.

In some cases, such a "remote" location that is not close to a power source, a PV system may be more cost-effective than installing power lines and step down transformers in applications such as electrical fencing, lighting, and water pumping. Maintenance requirements are often less for a PV system than, for example, a diesel generator.

Successful stand-alone systems generally take advantage of a combination of techniques (maximizing energy efficiency) and technologies (PV combined with a back up generator or PV combined with a wind turbine) to generate reliable power, reduce costs, and minimize inconvenience.

Water Pumping

Photovoltaic (PV) water pumping systems may be the most cost-effective water pumping option in locations where there is no existing power line. They are well suited for grazing operations to supply water to remote locations. Simple PV power systems run pumps directly when the sun is shinning, so they work hardest in summer months when they are needed most. Generally, batteries are not necessary because water is stored in tanks or pumped to fields and used in the daytime. Larger water pumping systems may include batteries, inverters, and a tracking system to follow the sun.

When properly sized and installed, PV water pumps are very reliable and require little maintenance. The size and cost of a PV water pumping system depends on the local solar resource, the pumping depth, water demand, and system purchase and installation costs. Although today's prices for PV panels make most crop irrigation systems too expensive, PV systems are very cost effective for remote livestock water supply, pond aeration, and small irrigation systems.

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