EG4 vs FranklinWH: DIY Hybrid System or Installer Whole-Home Battery?

EG4 vs FranklinWH is really a choice between two ways of building home backup. EG4 sells the parts for a DC-coupled hybrid system — an 18kPV inverter that takes solar, battery, grid and generator in one box, plus 48V LiFePO4 batteries — and leaves the design to you or your electrician. FranklinWH sells a finished, AC-coupled whole-home battery, the 15kWh aPower 2 with its aGate controller, through installers, with a 15-year warranty attached. New to the idea? Our hybrid inverter guide explains what one box like the 18kPV replaces.

Quick honesty first: I haven’t wired an EG4 stack or had a FranklinWH installed, and I won’t pretend I have. What I’ve done is read both spec sheets line by line, because whole-home backup is the thing I’d want most after years of living with power that cuts out without warning. Treat this as a careful comparison of published specs, not a field report.

EG4 vs FranklinWH specs side by side

The real EG4 vs FranklinWH difference: DC-coupled vs AC-coupled

With EG4’s 18kPV, solar panels feed DC straight into the inverter’s three MPPT inputs, which charge the batteries and power the house from the same box. Fewer conversions means less energy lost between panel and battery, and you buy one inverter instead of two. It’s the natural layout for a new system and the only sensible one for a property with no grid at all. For the full spec-sheet breakdown, including its idle draw and MPPT limits, see our EG4 18kPV review.

FranklinWH’s aPower 2 is AC-coupled. It has its own inverter for the battery but no solar charge controller, so it pairs with whatever solar inverter or microinverters the house already has. That’s a strength if you installed grid-tied solar years ago and now want backup: nothing on the roof changes. The trade-off is an extra AC-to-DC-to-AC step when the sun charges the battery, which loses some energy compared with DC coupling.

Off-grid use

For a fully off-grid home or cabin, EG4 is the more direct fit. Signature Solar lists the 18kPV for grid-tied, grid-assist or full off-grid operation, and the solar, battery and generator inputs are all in one unit. Adding capacity is a matter of more 48V batteries or a second inverter in parallel.

FranklinWH says the aPower system accepts energy from solar, grid, generator and EV, so it can keep a house running when the grid is down. But its design centre is the grid-tied home that needs backup, with the aGate deciding when to use solar, battery or grid. If you’re planning a property with no utility connection at all, confirm the off-grid configuration with a FranklinWH installer before committing. Our off-grid vs grid-tied vs hybrid solar guide explains why that distinction matters.

Installation, support and who you call

This is where the two brands split hardest. EG4 equipment is sold at retail, so a skilled owner can buy it and work with an electrician, or install it where local code permits. That saves money and gives you control, but you own the design. Battery-to-inverter compatibility, breaker sizing, permits and utility interconnection are on you or whoever you hire.

FranklinWH sells through installers. You pay for that in the quote, but you get one company responsible for design, permitting, commissioning and warranty claims. For a lot of homeowners that’s worth it. Either way, a 14–15kWh battery in a home is covered by fire codes; NFPA 855 sets the baseline for where residential energy storage can go.

Capacity and output: how they compare in practice

Per battery, they’re close: 14.3kWh for an EG4 PowerPro, 15kWh usable for an aPower 2. Output differs more. One 18kPV supplies up to 12kW continuous regardless of how many batteries sit behind it, as long as the bank can deliver the current. One aPower 2 supplies 10kW, and FranklinWH systems grow by adding more aPower units behind the aGate. For a typical house with a central A/C, well pump and electric range, both can carry essential loads; FranklinWH specifically rates a single unit to start a 5-ton A/C. To size your own needs, use our home battery backup sizing guide.

EG4 vs FranklinWH: who should buy which

EG4 makes more sense if: you’re building new solar and storage together; you’re off-grid or want to be; you want the most capacity and output for the equipment budget; or you’re hands-on and have a good electrician. It also suits buyers who want 48V batteries they can add over time; see our best 48V off-grid battery picks.

FranklinWH makes more sense if: you already have grid-tied solar; you want whole-home backup with one installer accountable for everything; or the 15-year warranty and 60MWh throughput coverage matter more to you than the up-front cost. It belongs in the same shortlist as the systems in our whole-home battery backup roundup.

Not sure you need a permanent system at all? Compare against portable options in whole-home backup vs portable power, and see how other installer systems stack up in Delta Pro 3 vs Powerwall. For the code side, the NFPA 855 standard is where installers start.

Frequently asked questions

Last updated: October 5, 2026. EG4 vs FranklinWH specs are manufacturer- and retailer-stated, not tested by WildJoule. We do not display live prices.