It seems that Enphase has added
a new page for their energy storage solutions which includes
a link to a preliminary datasheet for the Australian version of the AC Battery.
One thing that jumps out at me is that I see NO MENTION of the use of Engage cabling system. The datasheet makes no mention of Engage and
the page includes the following verbiage:
Enphase Website said:
Step One: Install mounting bracket on studs.
Step Two: Connect with standard AC wiring.
Step Three: Hang and secure AC battery to mounting bracket.
The picture associated with "Step Two" looks nothing like Engage and more like standard wiring in conduit. My impression is that they have been performing cost-take-out on the AC battery and they realized that there is little need for the on-roof ruggedization which Engage provides. I suspect they have also eliminated the MC4 connectors for similar reasons. In fact, I wonder if the inverters are packaged in a very different manner to their roof-mounted counterparts, even if the electronics are extremely similar. The other benefit of elimination of Engage cables is that an electrician can wire up the AC Battery using only what is already on his/her truck. Also, the wiring gauge is not limited to 12 AWG, allowing larger wires to be used, if desired in order to reduce wiring losses.
Just for reference, I will take this opportunity to pull my per-kWh calculation for energy stored in the AC Battery from
another thread
RegGuheert said:
For $1000, you get a battery which is guaranteed to cycle twice per day for 10 years. In other words, you will pay $1000/(365 days/year * 10 years * 2 cycles/day * 1.2kWh/cycle * 0.9 kWh/kWh) = $0.127/kWh for energy stored in the AC Battery. This number assumes there is no cost for additional PV and/or installation and that no other equipment is required to be purchased to connect the AC Batteries (not valid, since, at a minimum, Engage cable and breakers are required).
The US$0.127/kWh result does not include Engage in the calculation and the 90% round-trip efficiency (0.96*0.97*0.97) still seems correct, so that calculation should still apply.
No doubt the utilities are well-aware of the fact that consumer-level storage is coming. As such, I expect them to raise the price of grid-tied solutions so that they are a bit below that of a battery-based system. Perhaps 5 to 8 cents/kWh.
So that would leave the homeowner with a couple of risk factors to balance:
- Purchase the AC Battery with the warranty-based assurance that it will provide electricity for about $0.13/kWh for 10 years and trust that Enphase will be around to honor that warranty.
OR
- Stick with the utilities pay somewhat less now knowing that they will "alter the arrangement" repeatedly during that same 10-year period.
Unfortunately the problem with the utilities in CA is that they make their pricing schemes so complicated that very few homeowners are likely to have sufficient data to determine what the actual costs will be in their specific case. This fact in itself will likely drive some homeowners toward battery-based solutions rather than sticking with the utilities.