Most solar systems are grid-tie, in that they synchronize their output to your local electric grid, and feed any excess power into that grid. They do this by increasing their voltage output until all power generated by the panels is consumed, either by your house or by the attached grid.
Because of the way these systems are designed, they do not work well when the grid is not present. If grid power is down, and your solar system feeds power into your home electrical system, you will also be 'backfeeding' power into the grid. Since you likely cannot possibly generate enough power to satisfy your entire neighborhood's power usage, this will in effect overload your system. There is a second safety issue of feeding voltage into a grid system that the power workers are expecting to be dead. Electrical code requires these grid-tie systems to cease feeding power into the grid if the grid power is removed.
Most of these systems do this by just shutting down -- unlike backup generators with auto-transfer switches -- they usually do not have an automated method to disconnect the grid power while still powering your house.
If you were to provide some sort of disconnect, due to the nature of these systems, they would try to 'push' all available power into your house, because they're designed to force all available solar power into the electrical system. The grid can absorb this, but generally your home cannot.
They do have models that can function off-grid, and even models with attached batteries to handle surge loads and night-time operation, but these models are not as widely installed. Likely due to cost and/or owner education.
Because of the way these systems are designed, they do not work well when the grid is not present. If grid power is down, and your solar system feeds power into your home electrical system, you will also be 'backfeeding' power into the grid. Since you likely cannot possibly generate enough power to satisfy your entire neighborhood's power usage, this will in effect overload your system. There is a second safety issue of feeding voltage into a grid system that the power workers are expecting to be dead. Electrical code requires these grid-tie systems to cease feeding power into the grid if the grid power is removed.
Most of these systems do this by just shutting down -- unlike backup generators with auto-transfer switches -- they usually do not have an automated method to disconnect the grid power while still powering your house.
If you were to provide some sort of disconnect, due to the nature of these systems, they would try to 'push' all available power into your house, because they're designed to force all available solar power into the electrical system. The grid can absorb this, but generally your home cannot.
They do have models that can function off-grid, and even models with attached batteries to handle surge loads and night-time operation, but these models are not as widely installed. Likely due to cost and/or owner education.