Submitted by mikemcq on October 24, 2017
Some of the terms confuse me - hoping for help. The PW2 specs say capacity of 13.2kWh of "AC Energy". It says Power Factor Output Range is +/- 1.0 adjustable and Power Factor (full-rated power) of +/- 0.85. Round Trip Efficiency is given at 89%.
My scenario is pure backup power charged by the grid.
First, I am confused how to account for loads with power factors less than 1.0. For example, I have an old freezer with a power factor of 0.60 and a running amps of 2.0. This is 240VA but only 144W (120v * 2a * 0.6pf). Should I count 144(W) against the 13.2 capacity or should I be counting 240(VA)? Let's ignore duty and defrost cycles of the freezer as I can measure those separately.
Second, how do I account for Round Trip Efficiency of 89%? I don't care about some loss charging the PW2 - that's just a few extra bucks for kWh. I am more concerned of the impact when PW2 is supplying power during grid outage. Is this saying I will be losing a further percentage from 13.2 capacity due to inverter efficiency loss? If so, how much?