The solar roof was installed at the end of last August so its first month of production was September, 2021. The solar performed well in September but after the equinox production dropped dramatically.
Energy sent to the grid dropped to zero and that low performance lasted until the spring equinox.
Part of the low performance in January and February was due to snow cover on the roof. Our north facing roof slopes to the ground so the snow that slides off has no place to go. The Tesla team realized the abnormally low performance was due to snow and ice covering the roof collectors.
The roof performance for the first half of the year will probably mirror the performance for the second half which puts us at zero energy. Most of this year our most expensive electrical use has been broken. Our spa is an energy hog. So if I do get it operational this summer it will be interesting to see how much of the excess it uses.
Although the former 3.9 kw of solar panels helped offset our energy use, only the new solar roof has gained more energy than we have been using.
I called Tesla and asked if the roof was now producing as expected and they said it is. On a good full sun day in summer I should expect about 74 kW of production. Notice peak production at 9.7 kw is about 60% of the installed 16 kW.
The downloaded data from the Tesla app shows the quantity of solar production in Megawatts and the amount of Megawatts returned to the grid.
Another way to look at the data is the percentage of produced energy used from and returned to the grid. Only 12% of power these six months of use including snow covered months came from the grid. The difference in power coming from the grid (2.32 MWh) and going to the grid is the total net zero energy use. Here the difference is 1.06 MWh.
I hope we stay ahead of usage every year. Sometimes I use appliances that are heavy energy users, especially heaters in the RV if it has not been winterized and we get a cold snap. And as mentioned the 11 kW spa water heater is a huge draw. I want to eventually set up thermal water heat for the spa.