It is a common misconception that when there is sunlight outside and the solar panels are generating power, a solar installation will continue to provide power to the house even when there is load-shedding or an outage on the electricity grid.
Depending on the type of installation that you have, your solar system will work differently.
An off-grid system that does not have net-metering will almost always have a battery connected to it. As a result, when an outage occurs, the system will utilise solar and/or batteries to provide power to the appliances.
Grid-Tied / Net-Metering
In the absence of the electricity grid, a grid-tied net-metering system will turn itself off. This is to prevent power from the solar panels being fed into the electricity grid and injuring staff that are performing maintenance. What this means is that during an outage, your grid-tied system will not provide any power to the site.
This is commonly addressed by installing a UPS, generator or a hybrid solar system.
A hybrid solar system combines the ability of the grid-tied system to perform net-metering with a battery backup. In the event of a grid outage, the hybrid solar system will power some or all appliances (depending on the model and features) from a combination of solar and battery storage.
Unfortunately, hybrid inverters tend to be quite expensive - up to twice the cost of an equivalent grid-tied inverter.
Grid-Tied + Off-Grid
When outages are rare, an alternative to the hybrid inverter is to install a grid-tied inverter and pair it with a smaller and cheaper off-grid inverter.
The grid-tied inverter will reduce the electricity bill through net-metering.
The off-grid inverter will be connected to a smaller number of solar panels and, in the event of an outage, will use those solar panels and/or battery storage to provide power to a specific set of appliances.