Savings calculator
What could Wattlark add for your home?
A simple, inspectable model. Move the sliders to match your bill, array, battery and driving. The result is a range, not a promise, and every assumption is listed below.
Electricity plan
Estimated yearly savings
$1,354
Likely range $1,016 to $1,693 · 51% of your bill · about $113 a month
- Appliance scheduling$175/yr
- Solar self-use$593/yr
- Battery on price$331/yr
- EV smart charging$255/yr
Bill today$220/mo
With Wattlark$107/mo
After the Home Plus plan ($12/mo, indicative): $1,210 a year.
An illustrative model, not a quote or a guarantee. Real results depend on your tariff, equipment and habits. See the assumptions.
How the estimate is built
- Energy from your bill
- Monthly kWh = bill ÷ $0.18 per kWh, a flat reference price.
- Shiftable use
- 18% of non-EV household use (laundry, dishwasher, water heating) can move to a cheaper window; 80% of that is achieved.
- EV energy
- 0.30 kWh per mile; 85% of charging moves into the cheapest window.
- Solar yield
- 120 kWh per installed kW per month (about 4 kWh per kW per day, a mid-latitude average).
- Self-use share
- Unmanaged homes use about 35% of solar directly. With scheduling and a battery this rises toward 88%, at about 2.8 points per kWh of storage.
- Value of self-use
- Each extra self-used kWh is worth the avoided import price minus a $0.05 export credit.
- Battery arbitrage
- 0.6 cycles a day on 90% of capacity, round-trip efficiency 90%, 70% achieved; only on time-varying plans.
- Plan spreads
- Peak-to-off-peak spread: flat $0.02, time-of-use $0.10 to $0.20, dynamic $0.13 to $0.26 per kWh.
- Range
- The shaded range is ±25% around the central estimate. Total savings are capped at 55% of the current bill.