Balcony PV - surplus energy

Balcony PV excess energy control to avoid backfeeding

The domestic energy base load of a household is usually less than a PV balcony system generates. This raises the question: Where to put the surplus?
Feed-in, battery storage or immediate self-consumption through load switching. Due to the amount and duration of this surplus, there are a few things to consider.
The power consumption should be known and the consumer can be switched on and off variably, e.g. IR heating panel, air purifier, pond aeration or similar.
The energy surplus is consumed statically. The expenditure on devices for dynamic power control is usually quite high, also in relation to the total yield from a Balkon PV system.

- Release LG (DPT 1.*)
The switching command stops the http query and cyclic sender

- Additional service W (DPT 14.*)
This adjustable power value W determines the switching threshold.
The value depends on the additional consumer to be switched.

Functional elements
- Cyclic transmitter
The example works with an interval of 1 minute.

- http query/text processor - for querying and transmitting the current total power of the connected loads, which are determined via an additional meter at the flat connection.
In the example, the recording is done via a TASMOTA meter.

- Distributor/ buffer storage - for securing and distributing the power value

- Threshold value
Switches the additional consumer "ON" or "OFF" depending on the setting. The lower threshold (switch-on threshold) is set to 9 in the example.
The additional consumer switches "ON" when a value below 9 W is detected.
The upper threshold is variable, depending on the consumer that is connected as an additional load.
This value is specified via an input value.
In order to trigger the "ON" value for continuous surplus, "Repeat value cyclically" must be activated with a value within the minimum runtime (e.g. 3 minutes).

- Mathematics tool
Here, the value 10 is added for the upper threshold in order to always be above the value of the lower threshold.

- OFF Switching delay
To ensure that the additional load is operated with a minimum running time (e.g. 10 minutes), the staircase automat element is used.
The 1st ON switching command starts the function, further ON switching commands shift the OFF switch delay accordingly.

- Total power W (DPT 14,*)
Shows the measured value of the energy meter at the house connection

- PV Surplus Switching (DPT 1,*)
Is the switching command for the load in the event of PV surplus

Uwe Müller
(236; 2023.04)

Balcony PV - surplus energy

This logic group is compatible with: EP, LOM
*With the download you accept the Notes on use for logic groups.