If you have solar panels what happens if the power from the grid goes off?

Question

I am not talking about battery backup. Just solar systems that are connected to the grid.

Answer 1

In most locations, grid-tied photovoltaic systems are required to comply with the UL standard 1741, which says that if the grid goes down, the system must shut off.  So one typically would not have the expectation that the solar panels would carry them through a blackout.

However, if the panels put out the right voltage (say, between 150 and 340 volts DC), some devices could still be run straight off the panels, bypassing the inverter which has turned off.  Many modern PC's and flat panels fall into this category - anything with a line switching power supply.  Also, incandescent lights, and some compact fluorescent lights, would still run on 100-170 VDC.  Even some power tools would run on DC.  You would probably only resort to this kind of thing if there was a Katrina-class emergency, and you knew the grid would be down for weeks.

Answer 2

There must be a switching device to stop the current from flowing into the power lines when down or else you could hurt the people working on those lines! These switching devices cost.