Why West-Facing Solar Beats South in San Diego

Aiming Your System at San Diego’s 4–9 PM Peak

First, why “when” matters so much in San Diego

SDG&E prices electricity by time of use. In summer, the 4–9 p.m. on-peak window runs about 69.65¢/kWh in 2026 — while midday super off-peak sits closer to 38¢ and off-peak around 46¢. That’s not a rounding difference; peak power can cost nearly double the midday rate.

On top of that, the value of the solar you export to the grid (under SDG&E’s Net Billing rules) is lower than the retail price you pay to pull power back. So two things are true at once: power is most expensive in the early evening, and your exported midday surplus is worth relatively little. Both facts push in the same direction — the most valuable solar is the solar you use yourself, especially during the peak.

The problem with a south-facing array in the evening

A south-facing array peaks around solar noon and tapers through the afternoon. By 5 or 6 p.m. it’s producing a fraction of its midday output.

The trouble is that 4–9 p.m. is exactly when SDG&E charges the most, and exactly when your home is hottest and the AC is grinding. So a south-facing system is fading right as your most expensive, most cooling-heavy hours begin. You generate a big midday surplus (credited at a lower export rate) and then buy pricey power in the evening. It still saves money — but it leaves value on the table during the hours that matter most.

Why west-facing panels line up with the peak

West-facing panels shift the production curve later in the day. They give up a little total annual output compared to south — often in the ballpark of 10–15% less over a year — but they keep generating deeper into that 4–7 p.m. stretch, powering your AC directly from the roof during the first, most expensive hours of the peak window instead of pulling from the grid.

In a world where you’re rewarded for using your own solar when power is expensive, that timing is worth real money. A west-leaning design trades a small amount of total production for output that lands in your highest-value hours. For a household that comes home in the late afternoon and runs the AC hard until bedtime, that trade often comes out ahead on the actual bill — which is what you care about, not the theoretical annual kilowatt-hour number.

South, west, or both?

This isn’t all-or-nothing. Many of the best San Diego designs are a blend:

• South for maximum total generation and the biggest midday surplus.
• West to carry production into the late-afternoon peak.
• Sometimes a split across roof planes to smooth the curve so you’re covered from late morning all the way toward sunset.

The right mix depends on your roof orientation, your shading, and — importantly — your evening usage. A household that’s empty until 6 p.m. and then blasts the AC has a very different ideal layout than one that cools all afternoon or works from home.

What actually drives the recommendation

• Your daily rhythm. When is your home occupied and cooling? Evening-heavy usage favors a west lean.
• Your roof. Which planes exist, how big they are, and how they’re shaded often decides what’s even possible before preference enters the picture.
• Whether you’re adding a battery. With storage in the mix, orientation matters a little less (the battery handles the evening); without it, orientation is your main lever on the peak.
• Your rate plan. TOU-DR1 and EV-TOU-5 have different peak definitions, and the best layout follows the plan you’re actually on.

Where a battery fits

Orientation gets you part of the way, but the sun still sets during the 4–9 p.m. window. Even a west-facing array can’t cover 8 or 9 p.m. on its own. That’s where storage comes in: bank your daytime solar and discharge it across the whole peak.

Panel orientation and a battery aren’t competing strategies — they work together. Smart orientation reduces how much you have to lean on the battery, and the battery covers what orientation can’t. A west-leaning array plus a battery is one of the most effective setups there is for beating SDG&E’s summer evenings: the panels carry you into the peak, and the battery carries you through the rest of it.

A couple of common questions

Won’t west-facing panels lose me money by producing less overall? They produce a little less total energy, but they produce more of it during expensive hours. On a time-of-use bill, the timing of production can matter more than the raw total — which is the whole reason to consider west.

Is south-facing ever still the right call? Absolutely — for some roofs, usage patterns, and battery setups, south (or a south-heavy split) is best. The point isn’t “west wins”; it’s that the decision should be made on purpose, against your rates and your usage.

What this means for your design

The takeaway isn’t “always go west.” It’s that in San Diego, a good solar design is planned around when you’ll use power and when it’s expensive — not just how many kilowatt-hours the roof can make in a year. Two systems with the same number of panels can save very different amounts depending on how they’re aimed.

When we design a system, we model your roof planes against your actual load shape and SDG&E’s peak window, so your production lands where it’s worth the most — in the expensive evening hours when your AC is running.

Curious whether a west-facing or split layout would beat a standard south-facing design on your roof and your usage? Stellar Solar has been San Diego’s trusted solar installer since 1998 — A+ rated with the BBB and a repeat winner of San Diego’s Best Solar in the Union-Tribune Readers Poll. Get a free design consultation at your free quote here or call 866.787.6527.

from Stellar Solar https://ift.tt/AaTeUF9