Long Island Solar Installation Pros — Calculator
Home Battery Sizing Calculator
Plan a Long Island home battery system by selecting the loads you want to keep running during a PSEG outage. Critical-loads or whole-home — pick what fits your home and outage planning.
How this calculator works
Select the loads you want the battery to keep running during a PSEG Long Island (or municipal utility) outage. Adjust wattage and daily hours per load. The calculator sums the daily energy across all selected loads, scales it for your chosen outage duration, and adds a 20% buffer for inverter efficiency and depth-of-discharge limits.
For the full ROI conversation around batteries on Long Island — incentives, outage exposure, and when the math works, see our battery ROI resource.
Outage duration
How long do you want the battery to keep critical loads running? 12 hours covers most short PSEG Long Island outages; 24+ hours plans for nor'easter or tropical-system events.
Loads you want to keep running
Check the loads you want the battery to back up. Adjust wattage and daily hours if you know your appliance specifics — defaults are typical Long Island residential values.
Refrigerator + freezer
Daily: 1,200 Wh
Compressor cycles ~30% of the day; effective average load.
Sump pump (if applicable)
Daily: 1,000 Wh
High-wattage but typically runs intermittently during storms.
Well pump (if on well water)
Daily: 1,500 Wh
East End and some Suffolk homes only. Confirm pump wattage with installer.
Essential lighting (LED)
Daily: 360 Wh
Hallway + a few rooms only; LED-only.
Internet router + modem
Daily: 720 Wh
Runs continuously.
Phone/laptop charging
Daily: 300 Wh
Furnace transformer + blower (winter)
Daily: 3,600 Wh
Heat-only blower load (winter outage only).
Window AC unit (summer, single room)
Daily: 6,000 Wh
Summer outage planning only.
TV
Daily: 400 Wh
Microwave (occasional use)
Daily: 550 Wh
Estimate
Required battery capacity
4.3 kWh
Includes a 20% buffer for inverter losses + depth-of-discharge.
Continuous load (peak)
1,290 W
Sum of wattage if every selected load is running simultaneously.
Suggested battery size
Smaller home battery (~10 kWh)
Reference size — your licensed local installer confirms the actual sizing based on your electrical panel, circuits, and the loads you want on the backup loadcenter.
Reminders
- Battery backup is a planning option, not a guarantee of uninterrupted power. Runtime depends on actual load profile during the outage.
- Older 100A electrical panels may need to be upgraded before adding battery storage. This is surfaced during the planning assessment, not at install time.
- NYSERDA Long Island solar + storage installation incentive may apply when storage is paired with solar. Program rules change — confirm with the program administrator.
Want a real battery-sizing walkthrough for your home?
We'll review your electrical panel, circuit map, and the loads you actually want backed up — then walk through critical-loads vs whole-home sizing with a licensed local installer who has battery experience.
Request a battery-planning assessmentCommon questions
What size battery do I need for my Long Island home?
It depends on which loads you want to keep running and for how long. Most Long Island critical-loads backup designs (refrigerator, sump pump, well pump, key circuits, lighting, internet) fit a typical 10–13.5 kWh single home battery. Whole-home backup requires more capacity and typically multi-battery systems.
Will the battery keep my whole house running?
Not necessarily. Battery backup is a planning option, not a guarantee of uninterrupted power. Most Long Island homes use a critical-loads design that covers essentials (refrigerator, sump pump, well pump, lighting, internet, basic outlets). Whole-home backup is possible but requires a larger battery (or multi-battery) system and is materially more expensive. Heavy loads — central air conditioning, electric range, electric dryer, hot tub — drain a battery fast.
How long will a 13.5 kWh battery run my house?
Depends entirely on what you ask it to run. A 13.5 kWh battery can run a critical-loads design (refrigerator, sump pump, internet, lighting, basic outlets) for roughly 24 hours, but the same battery covering whole-home loads including AC or electric heat might last only 3–6 hours. The calculator above models your specific loads against your desired outage duration.
Does battery storage qualify for incentives on Long Island?
When paired with solar, battery storage may be eligible for the NYSERDA Long Island solar + storage installation incentive. The PSEG Long Island Battery Storage Rewards program offers payments to participating residential battery storage customers via aggregators. Federal residential incentive treatment of batteries has changed — the IRS Residential Clean Energy Credit applied to qualified property installed from 2022 through December 31, 2025 and is not available for property placed in service after that date. Confirm details with the program administrator and a qualified tax professional.
Do I need an electrical panel upgrade for a battery?
Often, yes — particularly for older Long Island homes with 100A electrical service panels. Adding battery storage typically requires either a 200A main panel upgrade or a separate backup loadcenter. This is surfaced during the planning assessment, not at install time. Your licensed local installer confirms the specific electrical scope for your home.
Want a real battery-sizing walkthrough?
We'll review your electrical panel, circuit map, and the loads you actually want backed up — and walk through critical-loads vs whole-home sizing with your licensed local installer.