How Solar-Electric Systems Work
System Meter
A system meter in a solar-electric system can measure and display several different aspects of the system's performance. At a minimum it should be able to:
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Track how full the battery bank is
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Indicate how much electricity the solar array is producing
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Display how much electricity is being used
Operating a system without a meter is like operating a vehicle without any gauges. So, a meter is definitelya necessity.
Main DC Disconnect
In a solar-electric system with batteries, a disconnect between the batteries and the inverter is required by the U.S. National Electric Code. Basically, the disconnect is a large DC-rated breaker that can be used to safely interrupt the flow of electricity from the battery bank to the inverter.
Often, the array DC disconnect is wired into the main DC disconnect (usually mounting on the side) as an additional breaker controlled by the main DC disconnect. This allows the PV array and the remainder of the DC circuitry to be safely powered off with one switch on the main DC disconnect panel.
Inverter
An inverter transforms DC electricity produced by the photovoltaic array and stored in the battery bank into alternating current (AC). If the solar system is going to be tied into the grid, the inverter must be designed to synchronize the electricity it produces with the grid's utility grade AC electricity. This allows the system's solar-produced electricity to feed back into the grid.
Most inverters used in solar systems often include a battery charger which can charge the batteries from another source, such as the grid or a generator. These are called inverters/chargers. This is a particularly useful feature during long periods of cloudy weather. An integrated inverter/charger is an option available on all North Star Energy Services units.
AC Breakers
The AC breakers provided the switches that allow the alternating current from the inverter to the electrical outlets to be safely interrupted. The breakers route the power from the inverter to a number of electrical outlets provided on a North Star Energy Services unit. Depending on the unit, there may be one or more breakers.
The AC breakers used in our systems are just like the ones you see inside your home's main breaker panel.
Summary
We've covered the basics of the technology and components that make up an off-grid solar system - from the collection of sunlight to create the DC electrical current to the inverter that creates the AC electricity you can use to power tools, equipment, appliances, and lighting.