Pure AC Battery Load-Shifting (No Solar) in CA: EcoFlow STREAM vs. DIY 5kWh Build?
Hey everyone, looking for a sanity check on a pure AC battery load-shifting setup (no solar panels).
I'm in California dealing with wild TOU rates—around **$0.82/kWh on-peak vs $0.13 super off-peak**. The plan is simple: charge a ~5kWh battery from the wall overnight, then backfeed through a microinverter from 4–9 PM to reduce my house's base load.
EcoFlow (STREAM / Delta Pro) is the obvious plug-and-play route, but getting to 5kWh+ with expansion batteries is easily **$4,000–$4,500+**.
Building it modular looks like it comes in around **~$2,200**:
* **Battery:** 48V 100Ah (5.12 kWh) EG4 LiFePO4 server rack battery
* **Inverter:** Hoymiles microinverter (UL 3700)
* **Meter/Control:** Shelly Pro 3EM + OpenDTU-OnBattery for dynamic zero-export
* **Charging:** 48V AC-DC smart charger on a scheduled plug + 2P DC breaker & pre-charge resistor
For anyone running a similar battery-fed microinverter setup:
**Hoymiles on constant DC:** How does the inverter hold up long-term being fed constant 48V DC from a battery instead of PV? Any overheating or MPPT hunting quirks?
**Zero-export latency:** How fast is the Shelly -> OpenDTU loop in practice? Does it throttle back quickly enough when heavy loads drop so you don't accidentally export to the utility?
**CA / Safety practicalities:** With CA moving toward UL 3700 plug-in rules, any major red flags running a certified microinverter + server rack battery on a dedicated circuit vs waiting for overpriced all-in-one consumer units?
Appreciate any feedback or tear-downs of this plan before I start ordering hardware.