Photovoltaic cells (PV) allow for the direct conversion of sunlight to electricity. Sunlight hitting a semi-conductor surface creates an electric potential, which can be collected and stored or used directly as direct (DC) or alternating (AC) current. Groups of PV cells can be arranged into arrays, or logical layouts, and connected together for greater energy collection. PV systems can be used to supply electricity to a building, charge batteries, or power machinery. They can also operate in parallel with and interconnected to the local utility grid.
Main Grid-tied PV system
This 2.4 kW PV array faces south and collects direct sunlight. The angle of the array can be adjsuted for maximum solar absorption. This system is tied into the local utility company. If the system generates more power than the Harmony House is using at any given time, it feeds back into the utility grid and the Center is credited accordingly. This means that our meter can sometimes turn backwards! Conversely, if the house load is greater than what the PV system is generating, we can draw power from the grid.
Off-Grid Greenhouse PV system
This 1.2kW off-grid PV array uses 3 batteries to store energy for use when the sun is not shining. Energy generated by this stand-alone system provides electricity for the greenhouse.
Solar Direct Springhouse PV system
These two 75 watt panels power a water pump located in the springhouse. When the sun shines, the pump pumps water up the hill to a storage container. Water from this cistern can then be used in the garden at pressure when needed (even when it is cloudy). In a sense, the water tank is being used as a 'battery' in the system.
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