John Sonmez · Mar 2024 – Apr 2026
Under NEM solar billing, you only PAY gas monthly. Electric charges accumulate as a credit/debit against solar and settle once per year at true-up (March). Your $82/mo average bill is almost entirely gas — electric is deferred and then paid in one annual shot.
| Month ↕ | Net Bill ↓ | Gas Service ↕ | Electric (gross) ↕ | kWh ↕ | Therms ↕ | BSC ↕ | Status |
|---|
Comparing same calendar months across 2024, 2025, and 2026. 2026 only has Jan–Apr data. Windows were installed Jul 31, 2025 (Phase 1) and ~Feb 2026 (Phase 2). Look for the trend shifting down after those dates.
| Month | Net Bill 2024 | Net Bill 2025 | Net Bill 2026 | YoY 25v24 | YoY 26v25 | Therms 2024 | Therms 2025 | Therms 2026 | kWh 2024 | kWh 2025 | kWh 2026 |
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Initial window replacement showing measurable efficiency gains. 13.2% drop in kWh is solid — that's direct thermal reduction from better insulation. Gas savings more modest at 4.8% likely because summer is already low-gas season.
Dramatic gas reduction (-36.6%) suggests the exterior coating + remaining windows made a major insulation difference. Electric kWh up slightly (+3.0%) — possibly colder winter, more heating via electric, or measurement noise across only 3 months.
At $300–$400/yr in utility savings, payback period is 70–90 years. The project may add home value and improve comfort, but it doesn't pencil out as a pure energy investment. The gas reduction is real and impressive — but the math on payback is sobering.
Your TOU savings opportunity (~$792/yr) does not justify a battery at current rates. No-battery wins on 10-year cost. If you want a battery anyway, buy don't lease — Sunrun is the worst option by far.
Your solar panels generate electricity. When you produce more than you use, excess goes to the grid and you earn credits. When you draw from the grid, those credits offset your charges. Once per year at true-up, SDGE settles the balance.
6.0 kW system
generates power
Uses solar first,
then draws grid
Buys excess solar
at wholesale rate
Credits accumulate
— no cash payment
Annual settlement
— pay balance due
NEM EV-TOU-5 is favorable for solar owners. Your 6.0 kW system offsets the majority of daytime usage. The 69% super off-peak usage means most of your grid draw happens at the cheapest rate. The main opportunity is shifting on-peak consumption (17%) — but as shown in the Powerwall tab, the economics don't support a battery to do it.