One of the biggest myths about renewable energy is that it isn’t reliable. Sure, the sun sets every night and winds calm down, putting solar panels and turbines to sleep. But when those renewables are humming, they’re providing the grid with electricity and charging banks of batteries, which then supply power at night.
A new study in the journal Renewable Energy that looked at California’s deployment of renewable power highlights just how reliable the future of energy might be. It found that last year, from late winter to early summer, renewables fulfilled 100 percent of the state’s electricity demand for up to 10 hours on 98 of 116 days, a record for California. Not only were there no blackouts during that time, thanks in part to backup battery power, but at their peak the renewables provided up to 162 percent of the grid’s needs — adding extra electricity California could export to neighboring states or use to fill batteries.
In the user manuals for the inverters I’ve looked at installing. Same is true for many battery inverters.
If they need to integrate with a grid supply at all, they must switch at precisely the right frequency. Mains frequency drifts and so that frequency must come from the grid.
Now some will also have a grid isolated mode where they can generate their own frequency when there’s no other option, but that’s not on all models as it’s a feature they don’t need for 99.99% of their life, especially when grid operators generally don’t want people energising the grid from their batteries when the mains is down as it puts workmen at risk. Cables become live at unexpected times. So if you do have an inverter capable of running without mains you also have to have isolation switch so you only energised your own wiring.
An alternative is a separate isolated output that only ever runs on the generated power and not the mains, but that’s a pain for all the rest of the time.
The systems I’ve interacted with used what’s called an ats, automatic transfer switch, to be sure you’re not energizing the grid so one can self support in an emergency.
I’ve never seen a system so far that wouldn’t run isolated, but maybe I’ve been lucky 🤷