We Were NetZero Briefly

Since we had three sunny days right when they commissioned the system, and because of passive solar heating, allowing us to turn off the mini-split heating system we were briefly NetZero. The two lines will probably not cross again until mid-summer. This chart will be updated occasionally here.

The solar panels (28 panels, 350 watts each, 9.8 kW system) were commissioned on Jan 3 and are producing electricity which is either used immediately by the house or sent back onto the grid. The typical definition for a NetZero house is a house that produces as much energy as it uses, which if one is being literal would not require being grid tied at all. In the winter time, in Northern climates this can be quite difficult to achieve when attempting to be Netzero though the use of solar panels, as the days are short and electricity use is elevated if one is using electricity to heat the home. It would require a very large solar array (2-3X larger then typical systems) and a large number of batteries to store the days solar output to use at night or excessively cloudy days. These off-grid systems often lead to compromises such as using wood/pellets instead to heat the home, and carefully managing battery power by putting off some appliance use during cloudy days.

In our “Net Metering” situation excess generated electricity is sent back to the grid turning the smart meter backwards giving us “credit” either for excess power we used in the past or excess power we may use in the future. In the winter time, where we have increased energy use (150-200% more) due to heating the house by electricity, and decreased solar capacity (30% yield vs summer) due the sun being lower in the sky and short days we will be using excess electricity from the grid. At some point in the year, probably in June or July we will cross the “NetZero” moment where we will have netted out the excess electricity we pulled from the grid during the winter months with the electricity we pushed to the grid. From that date forward we will be banking electricity which we can pull from in Oct-December.

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