The nice thing is that even if you have rain, it doesn't mean your system won't be producing. Depending on the clouds and rain, your system could still produce enough energy to power your house or to at least partially power it and extend the runtime of the Powerwalls. We've had a heavy downpour for the past hour or so and our solar system has been generating 0.6 kW to 1.3 kW throughout the storm. The house is only using 0.8 kW so I've actually been exporting back to the grid. If the grid was down, our production would still be enough to power the house and trickle charge the Powerwalls a tiny amount.
We have 4 Powerwalls so we're able to endure longer outages. Fortunately, the Denver area averages over 300 days of sunshine per year, usually more than places in California and Florida, so it's rare we'd have no solar production for more than a day or two. When we get snow, we clear off some of the panels and can usually be producing at 40% to 60% of our normal capacity within a day of a huge snowstorm. We did a 200+ hour off-grid test last year when we got close to a foot of snow. We've also had a couple other multi-day outages in the past two years and fortunately the sun has come back out before our Powerwalls ran out. We did have an issue in 2019 when we had full sun and the grid was down but our Powerwalls couldn't handle the solar production because they were down to 5% and increasing the frequency to keep warm in the extreme cold. The Powerwalls were in a cycle with the solar and production kept turning on and off throughout the day. Tesla made some adjustments to our inverters and the shutoff frequency so hopefully we won't have that issue in the future.
