Converting sunlight into electricity to power your household appliances not only saves you money, but is kind to the planet. One way to configure a solar power system in your home is by connecting directly to the mains power grid that provides your home with electricity. In the grid-tie system, any surplus generated power will be fed back into the grid and reflected in your energy bill. At times of low sun, extra power can be drawn from the power grid. The power inverter is at the heart of this system.
Things You'll Need
- Solar panels
- Combiner box
- Direct current breaker box
- Power inverter
- Grid disconnect
Wire through the strings of your solar panels into a combiner box that contains circuit breakers for each string. The type of the combiner box and the size of breakers you need depend on the number of solar panels installed.
Install a direct current disconnect switch where the cables from the solar array enter the house.
Fix a metal oxide varistor (MOV) across the direct current bus (a bus is a common electrical connection between multiple electrical devices). An MOV is used to protect circuits against excessive voltages and significantly increased current. This will reduce the possibility of a fire and protect the system from any damage caused by lightning.
Install a direct current ground fault interrupter (breaker box). This device acts as a cut-off point and opens the circuit when it detects a leakage current to ground from the direct current bus.
Install a power inverter. An inverter takes the power from the solar panels, which is direct current, and changes it into alternating current (AC). AC is the type of current in most household outlets and is what most appliances use. With this inverter, the electricity your solar panels produce will automatically reduce the amount supplied by the utility company. It will operate only when utility power is available. It automatically synchronizes its voltage to the utility line. If the grid is down, the inverter has to immediately shut down.
Install a main service disconnect. This is similar to a breaker box, and allows you to disconnect the flow of electricity between your solar system and grid-powered electrical system.
Finally, connect the main service disconnect to the power grid meter and mains distribution panel. This ties your solar energy power system to the utility lines and household power outlets, respectively.
Tips & Warnings
- Because the grid-tie system is directly connected to the utility lines, if the mains power shuts down your system will shut down too. A small battery backup system, which is charged by the power inverter, can provide an alternative energy source when the power lines are not operating.
- Seek expert advice before reconfiguring your electricity supply.
- Photo Credit power lines 2 image by John Keith from Fotolia.com