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NuWatt designs, installs, and manages solar, battery, heat pump, and EV charger systems across 9 states. One company, one warranty, one point of contact.
Get a Free QuoteEvery watt, every duty cycle, every runtime hour explained. Full transparency on how our planner recommends battery systems.
You toggle on the appliances and circuits you want to keep running during an outage. The tool includes 16 common residential appliances organized into 4 categories: Essential (fridge, lights, Wi-Fi, phone charging), Comfort (sump pump, TV, microwave, well pump), Heavy (stove, heat pump, EV charger), and Medical equipment.
For each selected appliance, the tool calculates: Average Load = Peak Watts x Duty Cycle. The total average load across all selected circuits determines energy consumption per hour. Peak load (sum of all peak watts) is tracked separately for overload checking.
For each battery model, runtime in hours equals usable capacity (kWh) x 1,000 / total average watts. The tool also checks whether total average load exceeds the battery continuous output rating and whether peak load exceeds the peak output rating, flagging overloads.
When the solar toggle is enabled, the tool adds estimated daily solar production (based on an 8 kW system and regional sun hours) to the battery capacity for an extended runtime calculation. This simulates a solar+storage system that recharges during daylight.
For customers in MA, CT, or RI, the planner calculates annual ConnectedSolutions demand response revenue. Revenue = enrolled battery capacity (kW) x utility rate per kW. This income offsets the battery cost over time.
Peak wattage, duty cycle, and average wattage for all 16 appliances in the planner. Sources: DOE appliance standards, manufacturer specs, and field measurements.
| Appliance | Peak (W) | Duty Cycle | Avg (W) | Category |
|---|---|---|---|---|
| Refrigerator | 150 | 100% | 150 | Essential |
| Freezer | 100 | 100% | 100 | Essential |
| LED Lights (10 bulbs) | 100 | 100% | 100 | Essential |
| Wi-Fi Router + Modem | 30 | 100% | 30 | Essential |
| Phone/Laptop Charging | 60 | 100% | 60 | Essential |
| Sump Pump | 800 | 20% | 160 | Comfort |
| TV + Streaming | 150 | 100% | 150 | Comfort |
| Microwave | 1,200 | 5% | 60 | Comfort |
| Well Pump | 1,000 | 10% | 100 | Comfort |
| Garage Door Opener | 500 | 1% | 5 | Comfort |
| Electric Stove/Oven | 2,500 | 15% | 375 | Heavy |
| Heat Pump (heating) | 3,500 | 100% | 3,500 | Heavy |
| Heat Pump (cooling) | 2,500 | 100% | 2,500 | Heavy |
| EV Charger (Level 2) | 7,200 | 100% | 7,200 | Heavy |
| Space Heater | 1,500 | 100% | 1,500 | Heavy |
| Medical Equipment | 300 | 100% | 300 | Medical |
| Spec | Tesla Powerwall 3 | Enphase IQ 5P x2 | Franklin aPower2 |
|---|---|---|---|
| Usable Capacity | 13.5 kWh | 10 kWh | 13.6 kWh |
| Continuous Output | 11.5 kW | 7.68 kW | 5 kW |
| Peak Output (10s) | 22 kW | 10.08 kW | 10 kW |
| Round-trip Efficiency | 97.5% | 96% | 89% |
| Warranty | 10 years | 15 years | 12 years |
| Installed Price | $14,200-$16,500 | $15,500-$18,500 | $16,000-$19,000 |
| Data Source | Tesla spec sheet | Enphase datasheet | FranklinWH docs |
Runtime (hours) = Battery Capacity (Wh) / Total Average Load (W)
Where:
Battery Capacity (Wh) = kWh x 1,000
Total Average Load = SUM of (Peak Watts x Duty Cycle) for all selected appliances
Continuous Overload: Total Average Load (W) > Battery Continuous Output (W)
Peak Overload: Total Peak Load (W) > Battery Peak Output (W)
If either condition is true, the tool displays a warning. Peak overload means the battery cannot handle motor start-up surges. Continuous overload means the battery will shut down under sustained load.
A homeowner selects essential circuits: refrigerator, lights, Wi-Fi, and phone charging.
No overload warnings: 340W is well below all continuous and peak ratings.
Daily solar production: 8 kW x 5.0 hrs = 40 kWh. At 340W average load, daily consumption is 340 x 24 = 8.16 kWh. Solar produces 4.9x daily demand, enabling indefinite backup during sunny days.
| State / Utility | Rate per kW | Season | Dispatch Events |
|---|---|---|---|
| MA (Eversource) | $275 | June-September | 30-60 events/summer |
| MA (National Grid) | $225 | June-September | 30-60 events/summer |
| CT (Eversource, UI) | $225 | June-September | 20-40 events/summer |
| RI (RI Energy) | $225 | June-September | 20-40 events/summer |
Revenue formula: Enrolled kW x Rate per kW = Annual Revenue. A 5 kW enrollment at $275/kW = $1,375/year. Source: Utility program filings with state PUC (updated annually).
Wattage values are averages for typical residential models. Your specific appliances may draw more or less. Check your appliance nameplates for exact ratings.
Battery capacity decreases in extreme cold. Lithium-ion batteries can lose 10-20% capacity below 32F. The planner uses rated capacity at 77F.
The tool compares individual battery models (or the Enphase 2-unit config). Stacking multiple Powerwalls or adding a second Franklin is not modeled.
DC-to-AC conversion losses (typically 3-5%) are not separately modeled. Round-trip efficiency partially accounts for this, but real-world runtime may be slightly shorter.
The solar recharge estimate uses annual averages. Winter production can be 50-60% lower than summer in New England, reducing extended backup time.
The demand response program is only available in MA, CT, and RI. Rates and program terms are set annually by utilities and can change.
Select your circuits, compare three battery models side by side, and see exact runtime hours for your home.
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