What do you mean by this? Are you telling me Emporia will only do solar offset if I have solar export in excess of 1.44kW?
No, I was referring to solar absorption, not offset. Offset will track very closely and the residual consumption is minor (they told me all the numbers but I forget where I noted them - I believe it was something like every 2 seconds for adjustment and below */-30W in terms of how closely it tracks consumption. This is for the new bidirectional charger powered off if the EV battery.
The 1.44kW is the minimum charging power (which should be the same for your smart charger if you are running off of 240VAC).
The EV charging standard has a minimum of 6A. 6A x 240VAC = 1.44kW.
So the Emporia will monitor export but will not start charging the EV until export power is at least 1.44kW (and I’d ideally like to know there is a user-settable threshold power level to avoid the sorts of thrashing you were alluding to).
So this means that in the morning as AC-coupled solar power generation begins to rise, solar power will reach load level and net consumption will turn to net export (or if you have been maintaining zero consumption by offsetting with EV energy, you will transition from zero export to power being exported.m).
That exported power will continue to increase until it reaches the level needed to start EV charging, at which point you’ll be back to zero export late in the afternoon when export power drops below 1.44kW and you’ll again be exporting down the ‘tail’ until export drops to 0W and you remain at zero consumption through to the next sunrise.
I guess I'm OK with that, I rather it exported some than turn on my space heater which ends up importing because now I'm over drawing the system. I think that is a safety margin they placed that no matter what, once you turn on the solar controlled appliance connected to a plug you still remain net positive. A user adjustable setting or a 15 minute peak consumption of the plug from the last month as the threshold would be a better way to manage it but I digress.
At the moment, I have an export agreement in place and so even if I’m only getting pennies-per-kWh I agree with you, better to export the tail than to dump (as well as the head).
But the way things are headed in California, sometime in the future I will face a choice: either pay a ‘solar tax’ of close to $400 per year today and likely over $500 tomorrow for the ‘right’ to export or become a regular old electrical customer that pays for consumption but never exports any energy, ever.
So on that future, exporting the head and the tail will be quite costly and if I can a True Zero Export solution that doesn’t cost an arm and a leg, I will do so.
On the tail, my Microinverters support zero export, so it will be easy for me to taper-back solar production after it has dropped below the 1.44kW minimum to keep charging the EV or after the EV is fully-charged.
But the head is problematic, if I start off in the morning with my Microinverters in Zero Export mode, there will never be any exported power to get the Empora to start charging.
What you really want for that phase is to have a smaller bidirectional-charger-like system based on a modest-sized house battery and much lower minimum charge power.
If I can start charging the house battery with ~20W of consumption and configure the charge power to maintain net consumption of 20-30W, even in Zero Export Mode, my Microinverters will ramp up all the way to the peak charge capacity of that battery charger.
If we assume that battery charger an go all the way to 2kW, all it takes then is the Emporia sensing the power going to the battery charger to device when to kick-off EV charging.
EV starts charging at 2kW, consumption shoots up ti 2kW, and battery charger drops all the way back down to the 20W minimum, at which point charge tracking can proceed.
The house battery will eventually be fully-charged at which point the EV charger will take over tracking responsibilities and when with the excess solar power drops below 1.44kW or the EV battery is fully-charged, the zero-export capability of the Microinverters takes over to avoid export of the tail.
Hopefully California takes long enough to impose these export taxes on us legacy customers that this full capability will materialize without needing to involve a great deal of DIYing, but this is the Teue Zero Export vision I’m working towards.
P.S. in terms of what you wrote above regarding ‘solar appliancces’, what I was told by Empoeua was that current functionality merely allows you to set a list of prioritization on smartplugs to specify the order in which they should be activated whe there is energy being exported.
That is next to useless and what I requested them to do was add an export power threshold as well as a minimum on time, mimimum off time, maximum number of cycles per day, and start/stop timers for each smart plug to make that capability more useful.
We’ll see if that ‘ticket’ goes anywhere..,
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