This equipment has several components.
- DC breaker box
- AC breaker box
- Charge controller
- Remote display and controller
The DC breaker box is the central place where the power to and from the batteries, the incoming solar power and the in and outgoing power from the Inverter/Chargers meet. The DC box is also the place where the negative DC conductor should be grounded to earth.
The Inverter/Chargers convert the Direct Current (DC) from the batteries and Solar to "standard" Alternating Current (AC). These inverter are rated in Watts of power that they can deliver. For example, an Outback VFX 3648 is capable of delivering 3600 Watts of power and operates at 48 Volts nominal. 2 of these will then produce a maximum of 7200 Watts of available power. To determine the correct inverter capacity, you will need to calculate the maximum load at any one time on the system.
Current = Wattage divided by Voltage. For example, an Outback Quad Stack (4 inverters) is rated at 14400 watts. Therefore 14400 divided by 240 volts = 60 amps. So the maximum current that you could draw from a quad stack is 60 amps per leg. You can also add up wattages to come up with a total capacity that is required. For example, you may run a well pump at 2400 watts, a microwave at 1500 watts and other loads at 500 watts maximum at any one time. You would then require a minimum of 4400 watts of inverter power.
The charge controller takes the incoming power from the solar array and conditions the power.
There are several things that the charge controller does.
- Modern charge controllers allow the solar modules to operate at the "Maximum Power Point" of the modules.
- The charge controller maintains the proper battery voltage for charging the batteries
- As codes change, some charge controllers now incorporate Arc fault protection and ground fault protection.
The AC breaker box is where the output of the Inverter/Chargers, the cables from the main house panel and the generator (if so equipped) meet. Normally, the inverters can by "bypassed" so that if the system requires servicing, the power from a generator can power the house loads.
The system remote allows for the programming of the equipment and display of operating conditions of the power system.
Again, all wires and cables entering or leaving these boxes need to be in conduit or code compliant cabling.
One important item to mention here is to stay away from the "off shore" boatload sale type of systems for "Off Grid" homes. They are usually a poor quality, difficult if not impossible to properly integrate and wire into a code compliant installation.
Remember, this is your primary source of power that you do not want to have fail!
Most will look similar to this picture and come in various colours. (some of these may be suitable for RV or temporary use)
Quality systems will generally use one of the following manufacturers.
- Outback Power
- Schneider (Xantrex)
- SMA (Sunny Island)
Proper integration hardware is available for these. Check for pictures that show the inverters properly hooked up with all the integration hardware such as conduit boxes, circuit breakers and the like.