Yesterday I dusted off a @homeassistant automation that tracks our grid power demand, and adjusts the EV charger to have it only send power to the car when there's solar to back it up. My guess is that it'll save ~2000kWh imported from the grid annually 🤔
My goal is to get from consuming ~43% of the solar we generate to over 60% by this time next year. Let's see how that goes!
This is a good idea. Sometimes a cloud will go past while I’m charging the car and suddenly I’m importing.
Is your EV your only store for energy? Hot water? After shifting all my consumption to sunlight hours I recently added a battery and that’s really helped.
Not sure if you can add a battery without losing your NEM2
@futuresprog We can add a grid-tied battery without losing our NEM2 as long as our total export rate doesn't exceed the faceplate on our inverter. I'm going to start with a couple of 2kWh plug-in Anker batteries which will cover ~2.5kWh of shifted load every day.
@futuresprog (we have a heat pump water heater that does most of its work by day (it's fed by warm attic air!), but I don't think we can make it a daytime-only thing just yet)
@chrisjrn @futuresprog you can "overheat" the water, if you have a tempering valve to mix cold water in to get the desired tap temperature, and even get another tank to store more energy.
Ah, that’s a good idea. It’s what was installed in my house. They call it a “mains pressure” system. There cylinder is nice and hot and the tempering valve brings it down before sending it throughout the house.
I’m curious if a heat pump cylinder is amenable to being turned on and off on a timer? Mind you, the peak draw of a resistive hot water element is far higher than the typical draw of the heat pump.
@futuresprog @chrisjrn you would need a contactor that's rated for the compressor load (which has some inductive power factor) but the unit has some software and might support a peak rate schedule already (or be spyware garbage)
Note you likely need an expansion tank in the plumbing to manage the extra pressure of higher temps.
Other than the inrush current as the compressor starts, is the load terribly high? I tried to find the graphs from Technology Connections.
No need for a separate expansion tank. Mine already has an over pressure valve (top) along with an expansion valve (bottom) that both drain out of the house during normal operation. I know because I had to replace them at great expense. 😭
@futuresprog @enobacon the compressor is an inverter, so there's no inrush current (quite the opposite, in fact). The current ranges between 250W and 340W for our 240L model, depending on whether it's aiming for output heat, or overheating for storage.
@futuresprog @enobacon also, most of them have scheduling computers built in so you don't need to worry about setting timers yourself, for the most part.
That’s good to know. 2.5kWh would be useful.
@futuresprog ~$150 per year in shifted load is my guess (peak/part-peak electricity shifted into off-peak moreso than just increasing solar usage)