Grid Tie Solar Power System w/ Battery Backup Drawing
Earlier this week we featured a drawing of a simple grid tie system. A common misconception about grid tie solar electric systems is that you will have a power source when the power goes out, although unless you have a battery backup system your system will go down when the grid goes down. Some people who need backup power and don’t mind the maintenance and replacements every few years of a battery bank consider a grid tie system with battery backup. Today’s drawing also comes from the Guide to Photovoltaic System Design and Installation by the California Energy Commission and features a battery backup system.
As you can see compared to the simple grid tie system, the battery backup system is a little more complex. It includes a battery system, which is typically a group of lead acid batteries, a charge controller to keep the system from cooking the batteries from an overcharge and a critical load sub-panel. The point of a battery backup system is not to power you entire house through a blackout but to provide backup power to your most important electrical loads in your home or business. The downsides of a battery backup system are the increased cost of the overall system, the maintenance of the batteries and the installation time of the system with batteries jumps up 40% compared to a system without batteries.
So it really depends on where you live, how reliable your utility company is and if you have loads in your house that need to be redundant. What do you think? Is adding batteries to your system worthwhile?