Best Whole-House Battery Backup Systems (2025)
A whole-house battery keeps your entire home running during power outages—not just a few devices. This guide covers
the best options from Tesla to portable alternatives.
For portable options, see our guide to the Best Solar Generators for
Home Backup.
Whole-House Battery Options
| System | Capacity | Output | Installation | Total Cost |
|---|---|---|---|---|
| Tesla Powerwall 3 | 13.5kWh | 11.5kW | Professional | $12,000-18,000 |
| Enphase IQ 5P | 5kWh (modular) | 3.84kW per unit | Professional | $5,000-7,000 per unit |
| LG RESU Prime | 16kWh | 7kW | Professional | $10,000-15,000 |
| EcoFlow Delta Pro (DIY) | 3.6-25kWh | 7.2kW (two units) | Self + electrician | $5,000-15,000 |
Professional vs DIY Installation
| Factor | Professional (Tesla/Enphase) | DIY (EcoFlow) |
|---|---|---|
| Installation Cost | $3,000-7,000 | $500-1,500 (electrician for panel) |
| Permits Required | Yes, usually | Varies by jurisdiction |
| Warranty | 10-year comprehensive | 5-year on equipment |
| Automatic Transfer | Seamless | Requires Smart Home Panel |
| Grid-Tie Capable | Yes | Limited |
How Much Capacity Do You Need?
| Home Size/Usage | Daily Usage | Min Backup (1 day) | Recommended |
|---|---|---|---|
| Small home, minimal use | 10-15kWh | 10-15kWh | 15-20kWh |
| Average home | 25-35kWh | 25-35kWh | 30-50kWh |
| Large home with AC | 40-60kWh | 40-60kWh | 50-100kWh |
Reality check: Most homes need 2-3 Tesla Powerwalls ($25,000-40,000) for full whole-house backup.
Many homeowners compromise by backing up critical circuits only.
Tesla Powerwall 3
Tesla is the market leader with the most seamless product. The Powerwall 3 integrates with Tesla’s ecosystem (Solar
Roof, EV charging) and offers the best software experience.
- Capacity: 13.5kWh
- Output: 11.5kW continuous
- Chemistry: LFP
- Warranty: 10 years
- Price: $9,500 + $3,000-7,000 installation
Pros
- Seamless automatic switching
- Excellent app and monitoring
- Tesla ecosystem integration
- High output (11.5kW)
Cons
- Expensive installed cost
- Long wait times for installation
- Must use Tesla-certified installers
EcoFlow Delta Pro: The DIY Alternative
The Delta Pro with Smart Home Panel offers Powerwall-like functionality at a fraction of the cost. It’s modular,
expandable, and doesn’t require Tesla’s installation timeline.
- Capacity: 3.6kWh base, expandable to 25kWh
- Output: 7.2kW (two units in parallel)
- Chemistry: LFP
- Total Cost: $5,000-15,000 depending on configuration
Pros
- Lower cost than Tesla
- Modular expansion
- Portable when not installed
- Faster availability
Cons
- Smart Home Panel requires electrician
- Lower output than Powerwall
- Less polished software
Critical Circuits vs Whole House
Full whole-house backup is expensive. Many homeowners back up only critical circuits:
- Refrigerator
- Lighting
- Internet/Router
- Medical equipment
- Sump pump
- Garage door
Critical-circuit backup requires only 10-15kWh (one Powerwall or one Delta Pro system), cutting costs by 50-70%.
Verdict
Best Premium: Tesla Powerwall 3. Best software, seamless integration, proven reliability.
Best Value: EcoFlow Delta Pro + Smart Home Panel. 50-70% less than Tesla with similar functionality.
Best Modular: Enphase IQ 5P. Add capacity in 5kWh increments as budget allows.
For portable alternatives, see: Best Solar Generators for Home
Backup.