Path-Q Solar
How should I estimate solar bill savings when my electricity rates vary by time of day?
Answer
Estimate savings by matching solar production and battery operation to hourly electricity use and the applicable time-based rates, then model fixed charges, export credits, demand charges if applicable, and seasonal changes. Annual solar kWh multiplied by one average rate is often misleading.
Key points
- Self-consumed solar may offset a different rate than exported solar receives.
- Solar production and household demand must be aligned by time, not only totaled annually.
- A battery can change when electricity is bought or exported, but losses and operating limits matter.
- Use representative weekdays, weekends, seasons, and high-use periods.
What it depends on
- Current utility tariff and export-credit rules
- Interval load data
- Hourly solar production
- Battery operating strategy and losses
- Fixed, demand, minimum, and time-based charges
Risks and trade-offs
- A tariff change can materially alter the value of solar or storage.
- Assuming all solar offsets the highest rate can overstate savings.
- A battery may improve timing value but add cost, losses, and degradation.
Information you may need
- Complete current tariff and export rules
- Interval electricity consumption
- Hourly production model
- Battery specifications and operating assumptions
- Planned rate or load changes
Your next step
What to do next
Build an hourly bill model using the applicable tariff and compare no solar, solar only, and solar-plus-storage cases over representative seasons.
Path-Q
Find the right next step
Answer a few questions and we’ll narrow your options.
Loading…
Some details may depend on your location, installer, utility, incentives, regulations, or specific property.
SQ00283