What Actually Stays On When the Grid Goes Down?
The truth about backup power that most solar companies won’t tell you upfront.
How did you fare during the last big storm? Did you lose power? If you’re like many Connecticut homeowners who lived through Tropical Storm Isaias—watching groceries spoil, losing Wi-Fi during critical work calls, or running extension cords to a neighbor’s generator—you already know the frustration. And you might assume that installing solar panels would solve this problem. Here’s the thing: it won’t—unless you also install a battery.
The #1 Misconception About Solar and Power Outages
Many homeowners believe that once they install solar panels, they’ll have power during outages. This is one of the most common—and most dangerous—misunderstandings in the solar industry.
The truth: Solar panels alone will NOT power your home during a grid outage. Not a single light. Not your refrigerator. Nothing.
Why? It’s actually a safety feature, not a flaw.
Here’s What Happens When the Grid Goes Down
With solar panels only (no battery): Your system automatically shuts off. This is required by electrical code (NEC 690.12) to protect utility workers who are repairing downed power lines. If your panels kept sending electricity to the grid, lineworkers could be electrocuted. So your inverter—the brain of your solar system—immediately disconnects from the grid the moment it senses an outage.
The result? You’re sitting in the dark, watching your neighbors with generators keep their lights on, while your expensive solar panels sit idle on your roof.
With solar panels + battery backup: Your system “islands” from the grid automatically. The battery and its gateway disconnect your home from the utility in milliseconds, creating your own private microgrid. Your solar panels can now safely charge your battery and power your home—completely independent of the grid.
Solar Only vs. Solar + Battery: Side-by-Side
Solar Panels Only | Solar + Battery Backup |
Panels shut off during outage | Panels continue powering your home |
No power to any circuits | Critical loads stay powered |
Food spoils, Wi-Fi dies | Refrigerator runs, you stay connected |
Wait for Eversource/UI like everyone else | Independent from grid restoration timeline |
No backup at night (panels don’t work) | Battery powers through the night |
What Actually Stays On: Critical Loads Explained
Not all appliances are created equal when it comes to backup power. Battery systems are designed to power your most important loads—what the industry calls “critical loads”—for extended periods. Here’s what matters most to Connecticut homeowners:
Essential Loads for Most Connecticut Homes
- Refrigerator/Freezer: ~150-200W continuous, 1,200W startup surge. Keeps food safe for days.
- Wi-Fi Router + Modem: ~20-30W continuous. Critical for remote work, staying informed, and communication.
- Sump Pump: ~500-800W when running, 1,500W startup. Essential during storms with heavy rain.
- LED Lighting: ~50-100W total for essential rooms. Safety and basic functionality.
- Phone/Laptop Charging: ~60-100W. Staying connected and charged.
- Medical Equipment: CPAP (~30-60W), oxygen concentrator (~300-600W). Non-negotiable for those who need them.
- Garage Door Opener: ~500W when operating. Get your car in and out.
Heavy Loads: What Requires Bigger Systems
- Central Air Conditioning: 3,000-5,000W running, 6,000-10,000W startup. Requires high-power battery systems or multiple units.
- Well Pump: 1,000-2,000W running, up to 4,000W startup. Critical for homes without municipal water.
- Electric Vehicle Charging: Level 2 chargers draw 7,200-9,600W. May need to be excluded or limited during outages.
- Pool Pump: 1,500-2,500W running. Nice to have, but usually not prioritized for backup.
How Long Will Your Battery Actually Last?
This is the question everyone asks—and the answer depends on what you’re powering. Here’s a realistic look at battery runtime based on typical Connecticut home scenarios:
Scenario 1: Essential Loads Only (~500W Average)
Running: Refrigerator, Wi-Fi, LED lights, phone charging
Battery Capacity | Runtime (Battery Only) | With Daytime Solar |
10 kWh (Enphase IQ 10) | ~20 hours | Multiple days |
13.5 kWh (Tesla Powerwall 3) | ~27 hours | Multiple days |
15 kWh (FranklinWH aPower 2) | ~30 hours | Multiple days |
Scenario 2: Essential + Sump Pump + More Lighting (~1,000W Average)
Battery Capacity | Runtime (Battery Only) | With Daytime Solar |
10 kWh | ~10 hours | 24+ hours |
13.5 kWh | ~13 hours | 24-48 hours |
27 kWh (2 x Powerwall) | ~27 hours | Multiple days |
Important: Runtime estimates are illustrative and depend on actual load, battery state of charge, temperature, and solar production during the outage. Your installer will design a system based on your specific needs.
When the Grid Goes Down: What Actually Happens?
The critical difference between solar alone and solar + battery backup
Solar Panels Only
No Battery BackupWaiting for Utility Company
Panels shut off for lineworker safety
Solar + Battery
Backup Power SystemYour Own Microgrid
Islanded from grid, running independently
💡 Why Does This Happen?
Solar panels must disconnect during outages to protect utility workers repairing power lines (required by NEC 690.12). A battery system "islands" your home—automatically disconnecting from the grid in milliseconds and creating a private microgrid. Your panels then safely charge the battery and power your home, completely independent of the utility.
Battery Showdown: What Can Each System Actually Do?
We’re technology-agnostic at SAVKAT—we fit the battery to your home, not your home to our inventory. Here’s an honest look at three leading residential battery systems available in Connecticut:
Tesla Powerwall 3
- Capacity: 5 kWh per unit
- Continuous Power Output: 5 kW—one of the highest in the industry
- Startup Surge: 185 LRA (can start central A/C, well pumps, heat pumps)
- Warranty: 10 years
- Best For: Homeowners who want whole-home backup capability, new solar installations, or need high-power output for demanding loads
- Key Feature: Built-in 11.5 kW solar inverter—can replace your existing inverter for a streamlined system
FranklinWH aPower 2
- Capacity: 15 kWh per unit (largest single-unit capacity)
- Continuous Power Output: 10 kW, with 15 kW peak for 10 seconds
- Startup Surge: 185 LRA (excellent for heavy motor starts)
- Warranty: 12 years
- Best For: Extended outages, homes with existing solar systems, or those who want generator integration
- Key Feature: “aGate” smart controller enables seamless backup generator integration—virtually unlimited backup during multi-day Nor’easters
Enphase IQ Battery (5P and 10C)
- Capacity: 5 kWh (5P) or 10 kWh (10C) per unit—modular, stack up to 4 units
- Continuous Power Output: 84 kW per 5P unit (scales with additional units)
- Battery Chemistry: Lithium Iron Phosphate (LFP)—safest and longest-lasting chemistry
- Warranty: 15 years—longest in the industry
- Best For: Homes already using Enphase microinverters, those who want to start small and expand, or prioritize longevity
- Key Feature: Built-in microinverters provide redundancy—if one fails, others keep working
Connecticut’s Energy Storage Solutions Program: Your Battery Just Got More Affordable
Here’s where it gets interesting. Connecticut offers one of the most generous battery incentive programs in the country through the Energy Storage Solutions (ESS) program, administered by the Connecticut Green Bank and the utilities.
Current Upfront Incentives *as of 12/15/2025
(Tranche 1)
Customer Category | Upfront Rebate |
Standard Residential | $250 per kWh |
Underserved Community | $450 per kWh |
Low-Income Qualified | $600 per kWh |
Grid Edge Customers* | +50% bonus on top of base rate |
*Grid Edge customers are those who consistently experience more frequent or longer outages during major storms.
What This Means in Real Dollars
For a standard residential customer installing a 13.5 kWh Tesla Powerwall 3:
- Upfront Incentive: 5 kWh × $250 = $3,375 off the purchase price
For a Grid Edge customer in a distressed municipality with a 15 kWh FranklinWH:
- Upfront Incentive: 15 kWh × $450 × 1.5 (Grid Edge bonus) = $10,125 off the purchase price
Plus: Performance-Based Incentives
The ESS program also pays you for allowing your battery to support the grid during peak demand periods (called “dispatch events”). This happens automatically and doesn’t affect your backup capability:
Program Years 1-5 | Program Years 6-10 |
$200/kW (summer) + $25/kW (winter) | $115/kW (summer) + $15/kW (winter) |
= $225 annually per kW | = $130 annually per kW |
For a 10 kW battery system, that’s an additional $2,250 in the first 5 years and $1,300 in years 6-10—totaling $3,550 in performance payments over 10 years.
Program Note: ESS incentive rates and availability are subject to change as program tranches fill. Current incentives shown are for Tranche 1. Participation requires enrollment in the passive and/or active dispatch programs. Your installer will verify current incentive levels and eligibility at the time of your proposal.
The Bottom Line: Is Battery Backup Worth It?
We get asked this question constantly: “Is the battery really worth $15,000?” Here’s how we think about it:
Financial Reasons
- Connecticut ESS incentives can reduce the net cost by $3,000-$10,000+ depending on your eligibility
- Performance-based incentives add $3,000+ over 10 years
- Time-of-use rate optimization (where available) provides additional daily savings
- Potential home value increase (buyers increasingly prioritize resilience)
Resiliency
- Tropical Storm Isaias left 800,000+ Connecticut residents without power, some for over a week
- Climate change is increasing storm intensity and frequency
- Remote work has made home connectivity mission-critical for many households
- Medical equipment, sump pumps, and refrigerated medications can’t wait for the utility
Independence
- No more helpless feeling during outages
- Your timeline, not Eversource’s
- One app to monitor everything: solar production, battery status, home consumption
- Peace of mind you can’t put a price on
Ready to Power Through the Next Storm? SAVKAT is Bristol, Connecticut’s local solar and battery installer. We don’t push one brand—we engineer the right system for your home, whether that’s Tesla, FranklinWH, Enphase, or another solution. Our in-house team handles everything from design to installation—one warranty, one phone number, no subcontractors.
Get a free backup power assessment and find out which battery configuration keeps your home running when the grid goes down.
