For an SDG&E homeowner comparing solar-plus-battery PPAs, ask the provider to check the clock behind the savings forecast. Household usage, modeled solar production and utility price periods need consistent timing. A spreadsheet can preserve your annual electricity total while putting some consumption in the wrong hour.
A qualifying no-upfront offer can help eligible homeowners access solar and storage without an initial equipment purchase. A well-documented forecast helps you compare the ongoing payments with the utility costs you may still have.
Why the hour matters for an SDG&E proposal
SDG&E’s Solar Billing Plan page, checked November 3, 2026, explains that import and export prices depend on time. Export credits reflect energy delivered in each hour. The page identifies 4–9 p.m. as the residential plan’s on-peak period and directs community-choice customers to their generation provider for applicable import and export pricing.
Confirm your actual tariff and generation provider before using those assumptions. An existing NEM account should not automatically be modeled as a new Solar Billing Plan account.
For a simple illustration, suppose one kilowatt-hour of household consumption is mistakenly assigned to 3–4 p.m. instead of 4–5 p.m. The daily total is unchanged, but the model may apply a different price period. Its estimate of how much solar directly serves the home or how the battery operates may also change. This is an illustration of a possible data error, not a claim that your bill or provider’s quote is wrong.
Ask how the modeling tool handles time
The System Advisor Model electric-load documentation gives one concrete example. SAM requires load timing to follow the weather file’s convention. Its documented assumptions do not account for daylight saving time or leap years. It also expects average power in kilowatts for each time step, rather than an unlabeled list of energy totals.
That does not establish how every solar company’s software works. Ask which tool and version prepared your proposal and how the provider converted your records to its required format. The provider should explain the treatment of daylight saving changes, missing records and repeated clock hours, where applicable.
Do not shift an entire file by an hour yourself. Correct handling depends on the source timestamps and the destination model. Keep the original export available so the provider can trace any adjustments.
Request a small, readable spot check
You do not need to audit thousands of rows. Ask for a sample day showing household use, modeled solar, battery charging or discharge, grid imports and exports, and the price periods used. Suggested questions are:
- Do source timestamps identify interval starts or interval ends?
- Are the records in local clock time, standard time or another time convention?
- How were daylight saving transitions and missing intervals handled?
- After conversion, do monthly energy totals still reconcile with the source records?
- Are weather, usage and tariff schedules aligned in the final calculation?
Monthly reconciliation is useful, but it cannot alone prove that every hour is correct. Our weather-input guide covers a separate question: which weather dataset drives the solar forecast.
Keep payments and backup expectations explicit
The CPUC solar guide explains that a PPA provider owns the solar equipment and sells its electricity under an agreement. Review the energy price, escalator, term, battery fees, maintenance and transfer provisions, plus remaining utility charges. A timing correction improves a comparison; it does not guarantee savings or change the signed payment terms by itself.
For backup, PG&E’s general battery guidance explains why available charge, supported circuits and household demand affect duration. Confirm output limits and outage reserve separately from bill-saving operation. Ordinary grid-tied solar alone generally does not provide outage power; recharge needs compatible backup equipment and suitable sunlight.
Bring your bill and the provider’s sample-day explanation to the West Coast Alternatives homeowner journey to discuss a proposal with clear assumptions.