Why We Design West-Facing Arrays Under NEM 3.0

For twenty years, solar design in California had one rule: point everything south. South-facing panels produce the most total energy over a year, and under the old net metering rules, every kilowatt-hour was worth the same. More production meant more savings. Simple.

NEM 3.0 broke that logic. Exported power now earns a fraction of what evening grid power costs — roughly $0.05–0.08/kWh out versus $0.40–0.59/kWh during the 4–9 PM peak. The question is no longer how much you produce. It's when.

The afternoon premium

A west-facing array produces less total energy than a south-facing one — typically 10–15% less over a year. But it shifts the production curve two to three hours later into the afternoon, exactly when time-of-use rates climb toward their peak. Under NEM 3.0 pricing, a kilowatt-hour produced at 5 PM can be worth several times one produced at noon.

When we model both layouts on a real roof with real SCE rates, the west-heavy design usually wins on dollars despite losing on kilowatt-hours. That's why you'll see us propose west-dominant layouts that would have been considered mistakes five years ago.

What this means for your roof

Every roof is different. Some homes have great western exposure; some don't. The point isn't that west is always right — it's that design should follow the rate structure you actually pay under, not a rule of thumb from a different era. When we build your proposal, the sun-path model shows exactly how your planes perform hour by hour, so you can see the reasoning instead of taking it on faith.