I need idea for a variable energy waste device

Hello everyone.
I need to keep my pv from backfeeding and already monitor the usage of the house with an emporia vue 2 with esphome and the solar inverter is also reporting its production.
Now i saw this great blueprint about variable pv power control, but what i need is a esphome or tasmota or something device that can create a load variable between lets say 50 watts and 800 watts.
Can anyone think of something?
Thx alot in advance

Which solar inverter do you use? Is there no way to limit its output?

Hello, no, this is 100% guerilla pv, nothing to regulate or limit, all i can think of is a multi relay board with 100 watt bulbs on each relay but i would not know how to get them all together logic wise.
If home use lower than 50 watt and pv production above 100 watt than start bulb 1 and so on but alos backwards in case home use goes above 200 watts than disable a bulb…
That part i dont know how to code in ha compatible ways

So I repeat the qiestion: which inverter do you use?

Oh sorry, its a 1000 watt chinesian grid tie. Branded vevor but thats prob not the maker

I don’t know if this will help you, Control the EV charging power with regard to the solar PV output and grid power reading - Share your Projects! / Themes - Home Assistant Community (home-assistant.io)

A PV inverter with no monitoring or reporting interfacing module can easily made ‘smart’ if you put a switchable power monitoring module between the inverter and the grid. I have 2 older inverters, both a SonoffPOWR2 with Tasmoto in front of them. They can’t measure bi-directional, but that is no big problem. In the night at least I see no power reported. During the day up to 1800W is reported.
If I want, I can switch the SonoffPOW to ‘off’ in case some energy provider starts charging me for returned/delivered energy or negative kWh price.
In addition. last summer I designed a SCR-dimmer around an ESP32 that is between the grid and a 1500W 120L waterboiler. I designed an algorithm that puts all excess power into that boiler. I also ordered a Shelly1PM, I might use that as it is smaller so more easy to build into a junction box or so. It is only 8A, that is actually not enough for my inverter.
Note that in august/september (1m underground is 12 degrees then here), there is not so much energy needed to heat up to 40 degrees Celsius (shower temperature), but I could go up to 85 degrees, which is also a hard extra max protection temp switch.

Switching off is the best/easiest method. I currently get into over-voltage problems, so anyhow 1 inverter is switching off already by itself.

Hello, can u share more info on that dimmer u r saying?
Sound like what i am looking for.
Does your logic regulate up and down by a value it sees?
I have my breaker box mo itored in every breaker and the mains so that i could provide the info to that logic to have it always keep 100 watt in the drawing and nothing exported.

Thx for any more info or project sharing

I got it working last summer, it is quite a prototype, it needs more work to get it safer.

But the core hardware is a TRIAC, control is via 2 opto-couplers. You only activate during part of the sine-wave (phase-cutting). See Dimmer - Wikipedia for some theory, it is an old principle. One thing you will need to take care of is heat dissipation of the TRIAC; with a steady voltage drop of 1V and 6A (for 1500Watt) current flowing through it, I get 6 Watts to dissipate and if you search for ‘SCR-Dimmer’, you will find cheap modules that claim 2000W or 4000W with a too small heatsink. They might meltdown and/or burn. I used TIC226 TRIACs 30 years ago, I know how hot it can get. There are better ways, but that is beyond the scope of this forum.

The steering/timing is in software running on the ESP32. I use Tasmota, it is only a few clicks to get it enabled on the right GPIO pin. ESPHome same story. Basically you send a number from 0 - 100 to it via MQTT that is the percentage of the maximum Watt (1500 in my case).

Then the principle is that I get the actually/instant Usage and Delivery number from my DSMR4.2 and raise the percentage to such a level that Delivery number gets down to 0. Because it is DSMR4.2 (only every 10 seconds) I have some spikes/mismatches when fast moving small clouds, but that is acceptable for me. I actually do not regulate down to 0 but 1%, so on average about 15W delivery. It needs a lot of extra control code to get it more convenient, I use Node-RED, in the past (10 years ago) some Linux shell script. I am sure it can be done in YAML/HA, but I don’t have enough time to dig into that.

I saw there is a device called ‘Ohmpilot’ that can be used to use excess energy, but it costs 700 Euros or so. A competitor device I saw a year ago costed 600 pounds or so, I forgot the name, but it made me create something myself which costs about 25 Euros (the materials).

But do you or someone else who reads this topic know Solar Inverter brands/types/lists that can be controlled manually in terms of how much power they are allowed to output? Meaning adhoc controlled/steered via MQTT and not costing more than 2 solarpanels?

I haven’t really seen anything, I mostly spend my time in studying MPPT algorithms w.r.t. solar. My ultimate wish/plan is simply to go off-grid, so no energy-company that keeps me on a leash.

Haven’t seen any that work with mqtt, but there are several out there that do limiting or zero export… you just tell them how much u want to draw from the grid (usually 100-200 watts max) and it handles it from there…