Grid defection is a real option
Grid-tied residential solar systems currently dominate the market, primarily due to historical net metering. As utility rate structures shift away from real net metering, increase unavoidable fees or restrict grid access, solar consumers are finding that going off-grid is becoming more economically viable.
Our recent study shows that grid defection is economically advantageous for many families because of these rate structure changes.
Consider a typical family in San Diego, for example. After an initial investment of $20,000 on the off-grid system (solar, diesel generator and batteries), they could pay 45 per cent less for electricity than if they remained connected to the grid.
The system would pay for itself in just six years, and even with a battery replacement, they would break even again in year eight. Over the lifespan of the system, these families could save over $40,000 in electricity costs.
Since our analysis using data from one year ago, battery costs have dropped even further, increasing the return on investment. Locations that were previously on the borderline of economic viability are now clear opportunities for grid defection.
These trends, coupled with increasing grid electricity costs and decreases in both solar and battery costs, have made economic grid defection a salient issue.
But this also raises concerns about potential “utility death spirals,” where as more customers leave the grid to save money, the ones who are left face higher electricity costs, prompting even more to leave until the utility is bankrupt.
Stay on the grid
This trend raises two major concerns. First, those who can’t afford to leave the grid — often the poorest households — will end up paying the most for left-over fossil fuel electricity from the grid. Leaving the grid requires a hefty up-front cost, and not everyone can afford it.
Second, our research shows that the diesel generators used as back up for off-grid solar and battery systems will cause significant pollution — even more than the grid in some locations.
Our results show that regulators must consider mass economic grid defection of PV-diesel generator-battery systems as a very real possibility in the near future. To prevent utility death spirals and increased carbon emissions, it’s imperative we have rate structures that encourage solar producers to remain on the grid.
The worst thing regulators can do is allow the electric utilities to increase unavoidable costs for their short-term profits. This can backfire, as utilities will lose customers entirely in the long run. With solar and battery costs continuing to decline, this problem is only becoming more urgent.