Having lived off-grid on solar for a while, and having set up or helped design other systems, I often get asked, How come my solar stops working when the grid power goes off?
A good question, and unfortunately, a point that many solar companies don’t tell you when they are selling you the system.
This is a grid-tied solar system problem only.
A solar system tied to the power grid has the advantage that when it is producing too much power for you to use, it will sell power back to the grid, thus reducing your power bill and sometimes even getting you credits.
Different places have different requirements about the max power you can push into the grid, but they all have one thing in common:
When the grid is down, your solar system must not push power into it.
Why is this? Mainly because if the power grid is down and you are still pushing power into it, you could make the problem worse, or even electrocute the people who come to fix it as they can’t control when the lines are live or not.
The cheapest way to install a grid-tied solar system is to just have it detect when the grid is down, and turn off. Therefore, you get no power to use from your solar when the grid is down.
Can this be fixed? Yes, but it usually cheaper to get it right from the start.
A system that does not have this problem generally will have some battery backup so that it has its own internal grid, thus providing you power all the time.
Such a system will either have a smart inverter that detects a grid and send power only if it already has power, or will have a separate grid detector which will then control the flow of power.
So, it is possible to have power for a grid-tied system when the grid is down, just make sure it is designed for it when you are putting one it.
If you are unfortunate enough to be in the situation where yours turns off when the grid power is out, there is hope. Look into it, and depending on your setup, it may not be as expensive as you think to upgrade.
Solar independence is great - start now.