You have built your solar panels and stored your energy in batteries. How are you going to use that power in your home? Batteries provide DC (direct current) electricity, and your home uses AC (alternating current) electricity. You need an INVERTER to convert the DC energy in to AC energy that is compatible with your home appliances.
Types of Inverters
There are basically two types of inverters, pure sine wave and modified sine wave.
Pure sine wave inverters create an alternating current that smoothly transitions positive to negative just like the power generated by the utility companies. This type of inverter is required if you wish to connect your generated power to the public electric grid.
A modified sine wave inverter creates a stepped alternating current. This is fine for most practical uses other than electronic or digital appliances that could be affected by the stepped power of the modified sine wave. Motors, can openers, vacuums, etc. these are the types of appliances that are well suited for using the modified sine wave inverters.
Inverters come in a wide range of power sizes, from small 75 watt to 4000 watts and larger. The price increases dramatically as the size goes up.
Typical inverter input voltages range from 12 volts to 48 volts and up. Here again, the higher the voltage, the higher the cost. For a normal home solar panel system, 12 to 48 volts is considered sufficient with the higher voltage systems used for higher current demands.
Inverters can be used three ways to supply power to your appliances.
Direct Power use. Appliances are plugged directly into the inverters power plug to provide electrical energy to the device. This is good if you only need to run one or two items at a time. Wired to Home Power Network. Here, the output of the inverter is wired into your homes power panel to provide electricity to your whole house, or to selected appliances or circuits. A licensed electrician is required to perform this installation. Grid-Tie Inverter. A grid-tie inverter is required where you will be connecting to the utility power grid and providing your excess solar generated energy to the rest of the neighborhood. The drawback of the grid-tie inverter is that if the neighborhood power is lost, then your inverter will shut down, thus preventing you from using your own stored electric power. I recommend you install a grid-tie inverter on a separate by-pass circuit that is only used to send power to the utility grid. You need an automatic transfer switch to disconnect you from the grid when the grid power is lost, and connect your main battery power to your house through a standard inverter. This will protect the grid and provide you with power when others are in the dark.
An Inverter is your critical element to using your solar generated power in the home. Assessing your power need will determine the right size and type inverter required for your home. Remember to have a qualified electrician connect your inverter to your home power panel, and only use a grid-tie inverter for when you have excess power to sell back to the utility company.