This is an on-grid solar system, the most popular type of solar setup in America.
To understand how it works, let’s see it in action as it powers a typical American home for a day.
Let’s begin at night.
At this point, relatively little power is being used.
The fridge, some phone chargers, and maybe the heating or cooling.
There’s no solar right now, so electricity usage is met by power imported from the grid.
In the morning, energy use spikes as the family prepares for the day.
They’re using kitchen appliances, hair dryers, hot water heating, and other devices.
Part of their energy needs will be met with solar.
But as the sun isn’t very strong yet, the home will continue to import from the grid.
At midday the sun is much stronger, and the solar system reaches max output.
This is also when electricity usage is at its lowest as everyone’s out for work, school or errands.
That means lots of surplus power is produced.
In an on-grid system, that surplus is exported to the grid.
In return, the utility “pays” for the power by crediting their electricity bill.
In states with net metering, homeowners have the advantage of selling their power at the same rate they buy it for.
In the afternoon, the sun moves downwards through the sky, causing solar output to drop.
However, power usage is still low as most of the family’s not home yet.
The system continues to export power for bill credits.
It’s evening; the setting of the sun means there’s no more solar.
Energy use now peaks as the family returns home and runs lights, entertainment devices and kitchen appliances.
Grid energy transfers now switch direction.
The home stops exporting and starts importing power instead.
It’s night again, marking the end of a daily energy cycle.
The on-grid system imported energy for much of the day
But this gets offset by the high energy exports achieved by the system during midday and afternoon.
In fact, a properly-designed on-grid solar system can achieve 100% offset of a home’s power requirements.
Which means electricity bills with zero net usage charges.
