What Happens to Your Solar Panels During a Power Outage?

This question surprises almost everyone who hasn't dug into solar system design: without a battery, your solar panels actually stop working when the grid goes down. That seems backward — the sun is still shining, the panels are still generating electricity — so why would the power go out in a solar home?

The answer is a safety feature. Standard grid-tied solar systems are required by electrical code to shut down when grid power is lost. The reason is to protect utility line workers who may be repairing the grid. If your panels are feeding electricity into a 'dead' line that a technician is working on, the results could be fatal. The inverter has automatic disconnects that shut the panels down when it detects the grid offline.

The solution is a battery system like the Tesla Powerwall. When properly configured, the Powerwall creates an 'island' — a micro-grid that includes just your home. When the utility grid drops, the Powerwall isolates your home from the grid and begins supplying power from stored electricity. Your solar panels, now connected to this island rather than the public grid, can continue operating and recharging the battery.

In the NZEL solar farmhouse, the Tesla Powerwall is programmed for this scenario. When the grid drops, the switchover happens automatically and nearly instantaneously — fast enough that most electronics don't notice. If the outage extends into the next day and the sun shines, the panels recharge the Powerwall while the grid is still out.

If you're considering solar without a battery, understand what you're getting: lower bills, but no backup. If backup power matters to you — and in an era of increasingly unpredictable weather, it probably should — budget for the battery from the start. It changes the nature of what your solar home can do.