I’m wondering if this is feasible. Or if anyone has even done it already.
I’m in Australia where power companies don’t want to pay you for solar you feed back into the system. At the same time if you use anything from the system they have really high peak rates.
So during the day my system would be producing anywhere between 2 to 6 kW. My reverse cycle air conditioner uses 6-8 kilowatts. So I cannot use it without incurring huge fees.
Instead I have a heater that can be run at 750 Watts or 1250 Watts or 2 kilowatts.
It’s a dumb heater so I can hook it up to a smart plug.
What I’m thinking is that I set an automation where if I am producing an excess of solar I would turn on the heater.
Eg I have solar Analytics and if it tells me I’m producing 2kw and using 500w, then I have 1.5kw excess in giving to my electricity company for almost free.
Then I would choose to use 750w on the heater. I want to leave some excess due to cloud and other changes.
Now it can’t be a simple on and off on a simple calculation because cloudcover can make it go up and down past the threshold many times in a short period.
In theory really the solar trends up then down, so maybe the dealing with cloud can be mitigated by simply needing a larger excess
And then obviously I would need to be able to enter how much I’m setting the heater on.
A resistive element (assuming your heater has one) can run at any wattage via a PWM signal.
Probably a bit expensive for a small heater but I use one of these on my hot water.
This diverts all surplus solar power to my HWS until its full and if the sun goes behind a cloud or you turn the kettle on, it adjusts the power draw as shown here on a really cloudy day (green is hot water power)
wow that’s interesting.
I’d want to do that as an automation for the small heater for now
but my a/c is a strange temperzone brand nobody’s heard of. It is so annoying, expensive to repair, oversized for our small place. I’ve been wanting to make it smart, bu nobody knows how.
Robin’s Mk2 PV routers are quite advanced with support for multiple loads, wirelessly controlled loads etc, it typically requires some tinkering to get it going but worth checking them out. You might also want check out the EmonTx or EmonPi at Open Energy Monitor Data is logged to EmonCMS, for which there is an integration available: emoncms integration
Have you done any calculations on this DRED SOLAR CONTROLLER?
I’m getting a new AC so it’s an option. But $1k to install, and if I’m just careful when I turn AC on it will take a while to pay back. Also doesn’t work with 3 phase systems, which apparently are more efficient.
