It's difficult to get directly from solar, because you normally need a buffer, unless your array is so big it can power your load directly. And if that is the case you probably will have a grid tie system already, which is buffered by the grid itself.
Provided you are NOT grid tie (because if you do the whole system is linked to grid voltage), On AliExpress there are a few inverter boards you can take that convert a DC voltage into an unregulated AC output like
this one. You Need 12 or 15V for the logic and the IGBT's hapilly take whatever DC voltage is there and convert it into an unregulated AC output. The peak voltage will be your solar panel output voltage. I use this with a water heater, since the AC output doesn't damage the thermostat contacts and the heater is not too fussy about whatever voltage it takes. You can set the output voltage and it should even be possible to do some form of crude MPPT with a micro by changing it's power draw to keep a certain input voltage.
If you go using
@400bird method above, I am working on a smart plug like device that measures the consumption just before your meter and if there is excess it can turn on a diversion load. It's work on progress, still, but so far I haven't found any other like solution that doesn't go into the $$$'s.
It uses smart plugs based on energy power meter IC BL0942 and the new Becken chipsets which are replacing the ESP8266. The link is
here. You need to download the latest version from the repository (at present
here).
Basically it measures your current energy flowing into / out of the house, so it should be installed just after your meter, before the breakers (use a global breaker or a bi-polar fuse to protect it). Self consumption is obviosuly not accounted - same for your utility meter. When there is power flowing in or out of the house you can run an automation, either directly or through home assistant to turn certain loads on or off.
If you have a grid tie system you should have some period of netmetering (15min, 60min). That is also accounted. For example, if you have 1KW production and netmetering of 15min, thechnically you can 'store' the equivalent to 250W during those 15 minutes - So your load doesn't necessarily need to be powered solely by the solar panels. If your AC draws 2KW you can still run it for 7 minutes on each 15min period (crude example) and average zero consumption from the grid. The system self adapts based on your actual consumption and available excess and on the last version I've added a 24h table showing past history.
