Here in the US for ITC (Investment Tax Credit) compliance, Tesla has programmed all solar-coupled Powerwalls to charge only from solar and not from the grid, the only exception being relatively infrequent Storm Watch emergencies. It is therefore in the interest of solar/Powerwall users to have the most robust solar production possible. Even if micro-inverters increase overall system cost somewhat, I am thinking that micro-inverters should be preferred over string inverters when installing solar systems that will be coupled with Powerwalls.
This month, we've had scarcely any solar production because of heavy snow accumulation on the roof, combined with freeze/thaw cycles and ice formation. As a result, our two Powerwalls have not been able to recharge, except for one Storm Watch event when we were thankfully able to refill them from the grid. At the same time, the Powerwalls lose roughly 3-5% charge per day keeping themselves on standby in the cold, as they are installed outdoors on a porch.
Thankfully, we have SunPower panels with micro-inverters. I was just able to clear off one relatively accessible panel today, and the rest of the snow and ice may just have to melt on its own, which could take weeks longer. However, even with just one panel clear, we should be able to generate enough power to at least keep the Powerwalls from discharging further.
At another family home, however, we have basic, commodity panels with a SolarEdge inverter and power optimizers. The roof on that house is much more accessible and has a gentler pitch, so I was able to go on the roof and clear six out of 14 panels. However, even after a couple of days of sun, we saw no solar production, and the inverter remained "asleep". Today, I went back up and cleared two more panels, or 8/14. Finally, the inverter started up. My solar installer confirmed that if the majority of the panels are not getting significant light, the inverter will not start even if a minority of the panels are in full sun. That would obviously not be ideal if we were trying to keep Powerwalls from going down to 0%.
Further, there is no issue with a single inverter being a single point of failure when you have a micro-inverter on each panel. If that SolarEdge inverter had gone bad during the last several weeks, we would have had trouble getting the installer back up to replace it due to the road conditions and snow chain requirements.
In a couple of weeks, I am going to be giving a talk on our adoption of "green technology to a local environmental group up here in the SoCal mountains. I am inclined to strongly recommend the use of micro-inverters for those considering installing solar coupled with battery storage. Unfortunately, this would rule out using Tesla to install the solar, as I don't believe they do micro-inverters. Does anyone see any holes in my reasoning?
Also, I will add that it could be advantageous to have at least a couple of panels that are tilted at a steep angle, or even vertical on the south side of the house. This could permit at least enough winter solar production to keep Powerwalls charged. We don't get heavy snow accumulation on the roof all of the time, but when we do, the likelihood of power outages is pretty significant.
This month, we've had scarcely any solar production because of heavy snow accumulation on the roof, combined with freeze/thaw cycles and ice formation. As a result, our two Powerwalls have not been able to recharge, except for one Storm Watch event when we were thankfully able to refill them from the grid. At the same time, the Powerwalls lose roughly 3-5% charge per day keeping themselves on standby in the cold, as they are installed outdoors on a porch.
Thankfully, we have SunPower panels with micro-inverters. I was just able to clear off one relatively accessible panel today, and the rest of the snow and ice may just have to melt on its own, which could take weeks longer. However, even with just one panel clear, we should be able to generate enough power to at least keep the Powerwalls from discharging further.
At another family home, however, we have basic, commodity panels with a SolarEdge inverter and power optimizers. The roof on that house is much more accessible and has a gentler pitch, so I was able to go on the roof and clear six out of 14 panels. However, even after a couple of days of sun, we saw no solar production, and the inverter remained "asleep". Today, I went back up and cleared two more panels, or 8/14. Finally, the inverter started up. My solar installer confirmed that if the majority of the panels are not getting significant light, the inverter will not start even if a minority of the panels are in full sun. That would obviously not be ideal if we were trying to keep Powerwalls from going down to 0%.
Further, there is no issue with a single inverter being a single point of failure when you have a micro-inverter on each panel. If that SolarEdge inverter had gone bad during the last several weeks, we would have had trouble getting the installer back up to replace it due to the road conditions and snow chain requirements.
In a couple of weeks, I am going to be giving a talk on our adoption of "green technology to a local environmental group up here in the SoCal mountains. I am inclined to strongly recommend the use of micro-inverters for those considering installing solar coupled with battery storage. Unfortunately, this would rule out using Tesla to install the solar, as I don't believe they do micro-inverters. Does anyone see any holes in my reasoning?
Also, I will add that it could be advantageous to have at least a couple of panels that are tilted at a steep angle, or even vertical on the south side of the house. This could permit at least enough winter solar production to keep Powerwalls charged. We don't get heavy snow accumulation on the roof all of the time, but when we do, the likelihood of power outages is pretty significant.
