SimpliPhi PHI 3.8 vs HomeGrid Stack'd Series 9.6kWh
The HomeGrid Stack'd Series 9.6kWh wins this battery comparison by a decisive margin. It delivers 9.6 kWh of usable storage with 9.6 kW continuous output and a 6,000-cycle rating. The 5.8 kWh capacity advantage provides 8 additional hours of essential-load backup.
Key Differences
- • HomeGrid Stack'd Series 9.6kWh provides 9.6 kWh vs 3.8 kWh usable capacity.
- • SimpliPhi PHI 3.8 achieves 98% round-trip efficiency vs 96%.
- • SimpliPhi PHI 3.8 is rated for 10,000 cycles vs 6,000.
Specifications Breakdown
Usable Storage Capacity
The SimpliPhi PHI 3.8 provides 3.8 kWh of usable capacity (3.8 kWh total, 100% DoD), while the HomeGrid Stack'd Series 9.6kWh offers 9.6 kWh usable (9.6 kWh total, 100% DoD). At an average essential-load consumption rate of 750 watts, the SimpliPhi PHI 3.8 provides approximately 5.1 hours of backup versus 12.8 hours for the HomeGrid Stack'd Series 9.6kWh. The HomeGrid Stack'd Series 9.6kWh's 5.8 kWh capacity advantage translates to roughly 8 additional hours of essential-load backup during a grid outage. The SimpliPhi PHI 3.8 is scalable up to 8 units (30 kWh total), while the HomeGrid Stack'd Series 9.6kWh scales up to 8 units (77 kWh total).
Power Output
The SimpliPhi PHI 3.8 delivers 3.8 kW continuous and 3.8 kW peak power, while the HomeGrid Stack'd Series 9.6kWh provides 9.6 kW continuous and 9.6 kW peak. The HomeGrid Stack'd Series 9.6kWh's higher continuous output means it can simultaneously power more demanding appliances during an outage. A central air conditioner typically draws 3-5 kW, a refrigerator 0.1-0.2 kW, and an EV Level 2 charger 7-11 kW. Peak power rating matters for motor-driven loads with high startup current, such as air conditioners, well pumps, and sump pumps. The HomeGrid Stack'd Series 9.6kWh's 9.6 kW peak is suitable for lighter startup loads.
Battery Chemistry & Cycle Life
The SimpliPhi PHI 3.8 uses LFP chemistry with a rated cycle life of 10,000 cycles (approximately 27.4 years of daily cycling), while the HomeGrid Stack'd Series 9.6kWh uses LFP with 6,000 cycles (approximately 16.4 years). Both use LFP chemistry, which is considered the gold standard for residential energy storage due to its inherent safety, long cycle life, and environmental friendliness. The SimpliPhi PHI 3.8's additional 4,000 cycles translates to approximately 11.0 more years of daily use before reaching the rated end of life.
Round-Trip Efficiency
The SimpliPhi PHI 3.8 achieves 98% round-trip efficiency versus 96% for the HomeGrid Stack'd Series 9.6kWh. This means for every 10 kWh of solar energy stored in the SimpliPhi PHI 3.8, 9.8 kWh is recoverable, compared to 9.6 kWh for the other. Over 10 years of daily cycling with 15 kWh average daily throughput, the more efficient battery saves approximately $164 in energy that would otherwise be lost as heat (at $0.15/kWh average retail rate). Higher round-trip efficiency is especially valuable in time-of-use rate environments where you are storing cheap off-peak energy for expensive peak-hour consumption.
Warranty & Long-Term Protection
The SimpliPhi PHI 3.8 carries a 10-year warranty, while the HomeGrid Stack'd Series 9.6kWh offers 10 years. Both offer identical warranty duration. Battery warranties typically guarantee the unit will retain 60-70% of original capacity by end of warranty, so the length of coverage directly impacts your financial risk over the system's lifetime.
Specification Comparison
| Specification | SimpliPhi PHI 3.8 | HomeGrid Stack'd Series 9.6kWh |
|---|---|---|
| Capacity | 3.8 kWh | 9.6 kWh |
| Usable Capacity | 3.8 kWh | 9.6 kWh |
| Power Output | 3.8 kW | 9.6 kW |
| Chemistry | LFP (Lithium Iron Phosphate) | LFP (Lithium Iron Phosphate) |
| Efficiency | 98% | 96% |
| Cycle Life | 10,000 | 6,000 |
| Weight | 36 kg | 114 kg |
| Warranty | 10 years | 10 years |
| Scalable | Yes | Yes |
5-Dimension Head-to-Head Analysis
1. Storage Capacity
Winner: HomeGrid Stack'd Series 9.6kWhThe HomeGrid Stack'd Series 9.6kWh provides 9.6 kWh versus 3.8 kWh — 5.8 kWh more usable storage. At typical essential-load consumption of 0.75 kW, this equals approximately 8 additional hours of backup power. This is a substantial capacity gap.
2. Power Output
Winner: HomeGrid Stack'd Series 9.6kWhThe HomeGrid Stack'd Series 9.6kWh delivers 9.6 kW continuous versus 3.8 kW. This is enough to run a central AC unit, refrigerator, and general household loads simultaneously. The 5.8 kW power gap significantly impacts what appliances you can run during outages.
3. Chemistry & Longevity
Winner: SimpliPhi PHI 3.8Both use LFP chemistry with SimpliPhi PHI 3.8 at 10,000 cycles vs HomeGrid Stack'd Series 9.6kWh at 6,000 cycles. LFP chemistry provides excellent thermal stability, long cycle life, and no cobalt dependency.
4. Round-Trip Efficiency
Winner: SimpliPhi PHI 3.8The SimpliPhi PHI 3.8 achieves 98% round-trip efficiency versus 96%. Over 10 years of daily cycling with 15 kWh throughput per day, the more efficient battery saves approximately 164 dollars in energy that would otherwise be lost as heat (at $0.15/kWh). The difference is moderate but compounds over the battery's lifespan.
5. Warranty Coverage
Winner: TieBoth carry 10-year warranties — equal long-term manufacturer protection.
SimpliPhi PHI 3.8
The SimpliPhi PHI 3.8 is a 3.8 kWh LFP battery module designed for residential and off-grid energy storage. It features 100% depth of discharge, 10,000-cycle longevity, a wide operating temperature range (-20°C to 60°C), IP65-rated enclosure for indoor or outdoor installation, and no active cooling or ventilation requirements. The 48V architecture is compatible with most off-grid and hybrid inverters including Sol-Ark, Schneider XW+, Victron, and Outback. Up to 8 units can be paralleled for 30.4 kWh total capacity. Acquired by Briggs & Stratton Energy Solutions in 2021, SimpliPhi pioneered safe, non-toxic LFP residential storage in the US market.
Pros
- + 10,000-cycle rating — among the highest in residential batteries
- + 100% depth of discharge with no capacity penalty
- + IP65 rated for direct outdoor installation without enclosure
- + -20°C to 60°C operating range — widest in the industry
- + No active cooling, ventilation, or thermal management required
- + Non-toxic, non-flammable LFP chemistry — safest battery chemistry available
Cons
- - 3.8 kWh per module requires multiple units for whole-home backup
- - No integrated inverter — requires separate inverter purchase
- - Higher per-kWh cost than newer competitors
- - 48V low-voltage system limits compatible inverter options vs high-voltage alternatives
- - Briggs & Stratton acquisition creates brand uncertainty
HomeGrid Stack'd Series 9.6kWh
The HomeGrid Stack'd Series 9.6kWh is a modular LFP battery system consisting of two 4.8 kWh modules stacked together, delivering 9.6 kW continuous power at a 1C discharge rate. The system is compatible with popular hybrid inverters including Sol-Ark 12K/15K, Schneider XW Pro, and Victron MultiPlus-II. Each module is individually managed with its own BMS, and the modular design allows expansion from 4.8 kWh (1 module) to 38.4 kWh (8 modules). 100% depth of discharge and 6,000-cycle LFP cells provide long-term value.
Pros
- + 1C discharge rate — 9.6 kW continuous from 9.6 kWh capacity
- + 100% depth of discharge — use every kWh you pay for
- + Modular from 4.8 to 38.4 kWh — add modules anytime
- + Excellent Sol-Ark compatibility — the most popular DIY pairing
- + Individual module BMS for redundancy and fault isolation
- + 10-year warranty with straightforward claim process
Cons
- - Indoor installation only — no outdoor-rated enclosure
- - 48V low-voltage system — higher current draw than high-voltage alternatives
- - No integrated inverter — requires separate compatible inverter
- - Floor-standing design requires dedicated floor space
- - Limited brand recognition compared to Tesla or Enphase
Choose SimpliPhi PHI 3.8 If...
- ✓ Maximum battery longevity (10,000 cycles) is your top priority
- ✓ You want to minimize energy losses during daily charge/discharge cycling
- ✓ Off-grid homeowners, safety-conscious buyers, and extreme climate installations needing the most durable and environmentally resilient LFP battery with industry-leading cycle life.
Choose HomeGrid Stack'd Series 9.6kWh If...
- ✓ You need more backup storage to cover overnight consumption or extended outages
- ✓ You need to power demanding appliances (AC, EV charger) simultaneously during outages
- ✓ Sol-Ark system builders and DIY-friendly homeowners wanting a modular, high-power LFP battery that grows with their energy needs.
Our Recommendation
The HomeGrid Stack'd Series 9.6kWh is the decisive winner in this battery comparison, outperforming the SimpliPhi PHI 3.8 in 2 of 5 dimensions. Unless you have a specific requirement that the SimpliPhi PHI 3.8 uniquely addresses, the HomeGrid Stack'd Series 9.6kWh is the stronger choice for virtually every installation scenario.
Frequently Asked Questions
Which is better, SimpliPhi PHI 3.8 or HomeGrid Stack'd Series 9.6kWh?
The HomeGrid Stack'd Series 9.6kWh wins this battery comparison by a decisive margin. It delivers 9.6 kWh of usable storage with 9.6 kW continuous output and a 6,000-cycle rating. The 5.8 kWh capacity advantage provides 8 additional hours of essential-load backup.
Which battery lasts longer?
The SimpliPhi PHI 3.8 is rated for 10,000 cycles versus 6,000 for the HomeGrid Stack'd Series 9.6kWh. SimpliPhi PHI 3.8 lasts approximately 11 more years of daily cycling. LFP chemistry generally outlasts NMC in cycle life testing.
Which battery provides more backup power?
The SimpliPhi PHI 3.8 provides 3.8 kW continuous (3.8 kW peak) versus 9.6 kW continuous (9.6 kW peak) for the HomeGrid Stack'd Series 9.6kWh. HomeGrid Stack'd Series 9.6kWh can run more appliances simultaneously during an outage. A central AC typically needs 3-5 kW, a refrigerator 0.2 kW, and an EV charger 7-11 kW.
Can I expand SimpliPhi PHI 3.8 or HomeGrid Stack'd Series 9.6kWh storage later?
SimpliPhi PHI 3.8: Yes, up to 8 units for 30 kWh total. HomeGrid Stack'd Series 9.6kWh: Yes, up to 8 units for 77 kWh total. Both offer the same scalability.
Which battery chemistry is safer?
Both use LFP (Lithium Iron Phosphate) chemistry, which is the safest lithium battery chemistry for residential use. LFP does not undergo thermal runaway, uses no cobalt, and is inherently stable.
Related Resources
Last updated: February 2026