Limit PV / Solar power generation to avoid feeding into the grid

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1

Open your Home Assistant instance and show the blueprint import dialog with a specific blueprint pre-filled.

Summary

This automation will react on changes of energy imported or exported from the grid.
It will control the Photovoltaic power generation by setting the limit to a value avoiding exporting to the grid

Required sensors / entities

GridPowerMeters:

Sensors measuring Grid import or export e.g. all 3 phases in W.
All power meters will be summed up to define the total grid import or export.

PVPowerMeters:

Sensors measuring PV Generation in W
If sevaral Sensors are selected, those will be summed up.

NonPersistantLimit:

Entity to set the non persistant absolut limit in W. It should be the non persistant limit to avoid too many writes towards the flash memory.

InverterOnlineStatus:

Entity indicating if the inverter is available (ā€˜Onā€™ ā†’ available)

Kudos for the simple algorithm and idea go to:

Change log

Version: 0.0.3 - Add parameter to define, at which feed in power the controller will get active. Also add parameter to select the control mode
Version: 0.0.2 - Improve Error handling in case sensors are unavailable
Version: 0.0.1 - Initial commit

2

Correct me if I am wrong, but the sole purpose of this setup is not giving free electricity to the network, right?

3

Itā€™s not free. Itā€™s cost someone a lot of money to generate.

For me my system costs make my ā€œfreeā€ electricity about Ā£1/kWh to generate.
My export tariff gives me Ā£0.04, so I lose Ā£0.96/kWh to be paid Ā£0.04.

The electricity company would still sell you my ā€œfreeā€ electricity at full market value, (mine is charging Ā£0.31-0.045 depending on tarrif).

Nice tidy profit for someone.

So, if I export based on economics, that would be stupid, right?

Everyones use case is different :smiley:

4

I meant free from the perspective of the electricity company.
So in the end you donā€™t want to make someone a good profit. Fair enough! I would probably do the same or even buy a small battery.

5

Currently you are allowed in Germany to install a PV system with up to 600 W AC generation power with hardly any requirments and registration efforts towards the grid operators.

If you want to install systems with higher power you need to ensure by technical means, that you will not feed into the grid. (If you want to avoid the registration efforts)

1 Like
6

Thanks for sharing @Andre83 :+1:

This works great with a wallbox that also collects the data (Zappi) and a Hoymiles 600

It would be great if this would be an accepted way in germany to avoid the bureaucracy when you just want to add two panels to your roof installation to cover you winter usage better.

7

If your system costs is what you payed to install the installation.
Then you do not have any ā€œrunningā€ costs.

So if you diminish your generation you get nothing.
if you put it to the grid you get 4cent.

I think you are better of getting 4cent.

BTW i think you calculated your ā€œcostā€ of running your installation wrong.
Because otherwise you better be stopping your installation completely. As your cost of ā€œrunningā€ is higher than what you pay your electricity company.

A correct way to calculate the cost of each kWh you generate is called LCOE (Levelized Cost of Energy)
Its the installation cost / amount of energy generated over its lifetime

Assuming your installation costs 5000ā‚¬
it will probably last for 25years
And produce 4500kwh/y

The LCOE will be 5000ā‚¬/ (25y*4500kWh/y) = 0.044ā‚¬/kWh

(please insert your own assumptions)

so if iā€™m not mistaken you will produce at ā€œBreak Evenā€ when you send it to the grid
And lose money if you reduce your generation to not go to the grid.
You will also increase the marginal ā€œcostā€ of running your installation less.

The best way YOU win money. is to increase your own usage of your own produced energy by utilizing it immediately.

That way you avoid the 0.31-0.45 ā‚¬ another time (which is higher than the LCOE)