Most houses with solar electric panels remain grid-tied, meaning the house is still connected to the utility’s grid even as it has the means to produce its own power. Off-grid houses, which once accounted for the lion’s share of installations, are now in the minority.
And that seems to make sense. Grid-tied houses get the benefit of solar electricity, but also can tap into grid when panels don’t produce enough power to meet demand. Net metering allows houses to sell power at times when the panels are over-producing, and grid-tied systems are cheaper because they don’t require banks of deep-cycle batteries.
But is the situation really that cut and dried?
In a Q&A post at GreenBuildingAdvisor, Tristan Roberts says a chat with an expert at the Department of Energy got him poking at these widely accepted premises.
“If that electricity is feeding into the grid, we were discussing the difficulty in accounting for environmental benefits,” Roberts writes. “It’s hard to know if the 2 kW that you fed into the grid at 12 p.m. really resulted in the utility being able to reduce their coal-fired output by 2 kW. In fact, there are a lot of reasons to conclude that nothing of the kind happened…The point of our conversation was that the best use of on-site renewables, from a thermodynamic and environmental point of view, is on site.”
Does this mean, he wonders, whether homeowners should be steered more toward off-grid installations, or systems that split the electrical load between on-grid and grid-tied generation?
Yes, grid-tied systems make sense
While it’s unrealistic to think that small amounts of electricity fed into the grid will allow fossil fuel plants to be shut down, there are benefits nonetheless,…