When making considerations on the size of battery you will need to ask questions as not all is as it seems.
Generic on-line, off the shelf quotes you get from Facebook ads will not show you this.
The graph shows several years of battery charging and discharging over a year. Not all the energy that you charge it with will be used in the house for several reasons. One reason is that there are inherent losses in the transfer of energy. The second reason and most importantly is the efficiency of the battery inverter. And what’s stated in % terms, DOES NOT relate to the operational needs of the inverter. How much energy does an inverter use in its operation and also when in standby?
My own system, pictured here shows the energy we charged the battery with and the amount we were able to use. As you can see, not all energy was used, due to the losses.
Whilst we have EnPhase Microinverters on the roof, under each panel, the EnPhase battery did not exist until late 2023 so our battery has a standard ‘string’ inverter. String and hybrid inverters should be considered the same in this respect.
A string inverter will use more energy when delivering the lower loads into the house because the whole inverter needs to run to convert the stored energy into usable energy. If you were using 150wh of a night time, just the low level background stuff whilst sleeping, the inverter in some cases could be using more energy than your actual load.
Within the EnPhase battery there is a series of microinverters, each controlling a row of cells. If you use a low load, then only one microinverter will run to deliver that load. As you increase your load in the property, the other microinverter’s open up to deliver the energy needed. We call this Power Match. Or should I say EnPhase call it Power Match.
There is a test being conducted right now, in lab conditions where 4 inverters are all hooked up to identical loads and each battery has the same amount of stored energy in them. Early tests, and these are not conclusive as of yet, indicate you will get more energy from the EnPhase battery because in itself, it uses less energy to operate.
Anyway, that’s enough from me, have a listen to what Michael Burgess from EnPhase says about this and more, in this two part interview recorded on Thursday 11th December.
Michael is the UK and Ireland Director for EnPhase
And Part two