Solar and the road to net-zero
"Net-zero" and "zero energy ready" are specific, definable targets — not marketing. Here is what they mean, and how solar PV, storage, and net metering fit into reaching them.
The logic of a net-zero home is simple to state and demanding to achieve: make the home need very little energy, then generate at least that much on-site from renewables. The order matters. Solar sized to power an inefficient house is expensive and wasteful; solar sized to power a tight, efficient one is modest and cost-effective. That is why everything on the energy-efficiency page comes before the panels.
What “net-zero” and “zero energy ready” actually mean
A zero-energy (net-zero) home is generally defined as one that produces, over the course of a year, as much energy as it consumes — drawing from the grid at some times and sending surplus back at others, netting to roughly zero annually. The U.S. Department of Energy's Zero Energy Ready Home (ZERH) program defines a related but distinct target: a home built to such a high efficiency level that a renewable-energy system could offset all or most of its annual energy use. A ZERH is "ready" for net-zero even if panels are not installed on day one. The RESNET HERS Index puts numbers on this: a HERS score of 0 represents a home that produces as much energy as it uses.
Solar PV basics
A residential photovoltaic (PV) system converts sunlight to direct-current electricity in the panels, which an inverter converts to the alternating current your home uses. Output depends on system size (kilowatts), your roof's orientation and tilt, shading, and local sun hours. The U.S. Department of Energy and its National Renewable Energy Laboratory publish tools and guidance (including the PVWatts calculator) for estimating production for a specific address — the responsible way to size a system rather than relying on rules of thumb.
Sizing the system
Correct sizing starts from your actual annual electricity use (in kilowatt-hours), reduced first by efficiency upgrades, then matched to the production your roof can realistically deliver at your location. An efficient home needs a smaller array than an inefficient one of the same size — the single biggest lever on solar cost. Get a site-specific production estimate and a load analysis before committing to a system size; installers and the NREL tools can both inform this.
Battery storage
Solar panels produce when the sun shines, which rarely matches when a household uses the most power. Battery storage captures midday surplus for use in the evening and provides backup during outages. Batteries add cost and are not strictly required for a grid-tied net-zero home — the grid itself can act as the "battery" through net metering where available — but they add resilience and self-consumption. Whether storage pencils out depends heavily on local utility rules and rates.
Net metering — and why local rules decide everything
Net metering is the billing arrangement that credits you for surplus solar energy exported to the grid, effectively letting the grid store your daytime overproduction for nighttime use. It is central to the economics of grid-tied net-zero, but the details are set at the state and utility level and vary widely — full retail-rate net metering, lower export credits, or time-of-use structures all exist and change over time. Because these policies differ by jurisdiction and are periodically revised, confirm your specific utility's current net-metering or successor-tariff terms before modeling payback. The DSIRE database (referenced on our incentives page) is a good starting point for what applies where you live.
Reduce loads with a tight envelope and efficient heat pumps → get a site-specific solar production estimate → size PV to your reduced annual use → decide on storage based on local utility rules → verify net-metering terms before you model payback. Efficiency first is what makes the solar small and the math work.