https://github.com/italoc/silla-prism-integration
Beta Home Assistant custom integration for Silla Prism EVSE with MQTT solar and home-battery balancing.
https://github.com/italoc/silla-prism-integration
battery custom-integration ev-charging evse hacs home-assistant mqtt silla-prism solar
Last synced: about 2 months ago
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Beta Home Assistant custom integration for Silla Prism EVSE with MQTT solar and home-battery balancing.
- Host: GitHub
- URL: https://github.com/italoc/silla-prism-integration
- Owner: italoc
- License: gpl-3.0
- Created: 2026-05-17T16:19:35.000Z (2 months ago)
- Default Branch: main
- Last Pushed: 2026-05-26T19:52:09.000Z (about 2 months ago)
- Last Synced: 2026-05-26T21:21:02.123Z (about 2 months ago)
- Topics: battery, custom-integration, ev-charging, evse, hacs, home-assistant, mqtt, silla-prism, solar
- Language: Python
- Homepage:
- Size: 1.63 MB
- Stars: 0
- Watchers: 0
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
- Roadmap: ROADMAP.md
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README
# Silla Prism Solar custom integration
This repository contains a custom integration to integrate a Silla Prism EVSE
inside Home Assistant.
## Fork status
This project is a fork of
[persuader72/silla-prism-integration](https://github.com/persuader72/silla-prism-integration).
The original project provides the base Silla Prism MQTT integration; this fork
adds experimental solar and home-battery charging logic.
> **Beta notice:** this fork is still in beta. The solar balancing features can
> actively change the current limit and operating mode of the EVSE through MQTT.
> Test carefully with conservative limits before relying on it unattended.
## New features in this fork
- Solar battery balancing switch per Prism charging port.
- Dynamic EV current control from Prism MQTT data, grid import/export, EV output
power, port voltage and a Home Assistant home-battery power sensor.
- Optional home-battery SOC sensor selected directly from Home Assistant.
- Entity selectors for both the home-battery power sensor and SOC sensor, so the
configuration no longer requires manually typing entity IDs.
- Configurable single-phase or three-phase surplus calculation.
- Configurable target grid export, import/export deadband and stable-surplus
start delay to avoid chasing noisy measurements.
- Slow current ramp-up and fast ramp-down to reduce unwanted grid imports.
- Residual export recovery, which increases current by 1A after stable unused
export remains available.
- Proportional current correction, so large sustained export can increase
current faster while real import can reduce it faster.
- Automatic home-battery priority based on SOC:
- low SOC reserves the configured battery charge power for the home battery;
- medium SOC reserves a smaller configurable amount;
- high SOC reserves an even smaller configurable amount;
- SOC >= 95% gives priority to the EV.
- In solar mode, temporary low surplus no longer pauses the port; the
controller keeps the EVSE in solar mode at 6A and raises current again when
surplus returns. If the current limit was changed manually, that manual limit
is preserved while low surplus remains. If Prism enters autolimit because of
house-load protection, the controller waits until grid import is back inside
the configured deadband, then makes one 6A recovery attempt with a cooldown to
avoid command loops. If Prism reports paused mode/state, for example because a
charge limit was reached, the controller respects that pause and does not
force solar mode again.
- Diagnostic sensors for calculated surplus, target current, grid power,
battery power used in the calculation and controller decision reason.
## Installation
Prerequisites: A working MQTT server.
1) Configure the Prism EVSE to work with your MQTT server as shown in the
[Prism MQTT manual](https://support.silla.industries/wp-content/uploads/2023/09/DOC-Prism_MQTT_Manual-rel.2.0_rev.-20220105-EN.pdf).
2) Configure and enable the [MQTT integration](https://www.home-assistant.io/integrations/mqtt/) for Home Assistant.
3) Install this custom integration with HACS as a custom repository, or copy the
`custom_components/silla_prism` directory into your Home Assistant
`custom_components` directory.
## Usage
1. Add the Silla Prism integration from the Home Assistant dashboard.
[](https://my.home-assistant.io/redirect/brand/?brand=silla_prism)
2. Keep note of base path for all Prism topics
3. **Topic**: set the base path for all Prism topics. It must match the value
configured in Prism. Keep the trailing **/** at the end of the topic.
4. **Number of ports**: if you have more than one port, for example Prism Duo,
set the matching number of ports. For a single-port Prism, keep the default
value of `1`.
5. **Serial number** or **unique code**: if you have more than one Prism
connected to Home Assistant, fill this with a unique value, such as the serial
number. For a single Prism, this can stay blank.
6. **Enable virtual sensor**: enables additional sensors derived from the
original Prism sensors, such as total energy imported from the grid.
7. Configure the integration options. The setup form now includes inline field
descriptions and examples for the solar battery balancing options.
The first part contains the MQTT topic, the maximum current limit, the switch
that enables solar battery balancing, and the Home Assistant sensors used for
home-battery power, real solar production, optional house load and SOC.
Select the battery power sensor in W and, when you want the direct
solar-minus-house calculation, select both a solar production sensor in W and
a house load sensor in W. The house load sensor should exclude the EV charger
when possible; if your meter includes the EV charger, create a template sensor
that subtracts Prism EV output power. Enable the battery sign option when your
battery sensor is positive while discharging and negative while charging.
The second part sets the low-SOC battery reserve, the number of EV charging
phases, the stable surplus delay, and whether battery charging power can be
treated as EV surplus. Use `1` for single-phase charging or `3` for
three-phase charging. In solar mode, low surplus is held at 6A instead of
pausing the port, so the delay only affects when current can rise above the
minimum.
The third part defines the SOC thresholds and the power still reserved for
the home battery at medium and high SOC. It also sets the target grid export,
the import/export deadband, and the minimum interval between current
increases. These values decide how aggressively the controller gives direct
solar production to the EV while avoiding unwanted grid import.
The last part controls the current ramp steps and residual export recovery.
The increase step limits how quickly current rises, the decrease step lets
the controller react faster when house loads appear, and residual export
recovery adds current again if export remains unused for the configured time.
## Solar battery balancing
The integration can optionally create a `Solar battery balancing` switch for each
charging port. When enabled, it reads the Prism grid power, the Prism output
power, the port voltage and a Home Assistant battery power sensor, then updates
the Prism current limit so the EV uses only the available solar surplus without
discharging the battery.
Configure it from the integration setup/reconfigure form:
| Option | Description |
| ------ | ----------- |
| Enable solar battery balancing | Creates the balancing switch. |
| Battery power sensor | Home Assistant entity that reports battery charge/discharge power in W. |
| Solar production power sensor | Home Assistant entity that reports real PV production in W. Use this instead of Prism `energy_data/power_solar` when that topic is not populated. Required when the home load sensor is configured. |
| Home load power sensor | Optional Home Assistant entity that reports house load in W, preferably excluding the EV charger. When set together with the solar production sensor, the controller uses external solar production minus external house load to calculate EV surplus. |
| Home battery SOC sensor | Optional Home Assistant entity that reports the home battery state of charge in %. |
| Battery discharge is a positive value | Enable this if the sensor is positive while the battery is discharging and negative while charging. Disable it if your sensor uses the opposite sign. |
| Maximum battery charge power | Battery charge power, in W, reserved for the home battery while SOC is low. Default is `2700`. |
| Number of charging phases | Use `1` for single phase or `3` for three phase charging. |
| Stable surplus delay | Minutes of continuous surplus required before the integration starts charging. The default is `5`. |
| Use battery charge as surplus | When enabled, battery charging power is also treated as available EV surplus. This gives the car priority over storing that solar energy first. |
| Medium home battery SOC | SOC threshold where the reserved battery charge power drops to the medium reserve. Default is `40`. |
| High home battery SOC | SOC threshold where the reserved battery charge power drops to the high reserve. Default is `80`. |
| Medium SOC battery reserve | Approximate maximum battery charge power, in W, kept for the home battery at medium SOC before sending the rest to the EV. Default is `1500`. |
| High SOC battery reserve | Approximate maximum battery charge power, in W, kept for the home battery at high SOC before sending the rest to the EV. Default is `1000`. |
| Target grid export | Watts to intentionally keep exported as a safety buffer. Default is `150`. |
| Import/export deadband | Watts around the target export where current is left unchanged. Default is `150`. |
| Minimum current increase interval | Minimum seconds between upward current steps. Default is `15`. |
| Maximum current increase step | Maximum amp increase per ramp step. Default is `1`. |
| Maximum current decrease step | Maximum amp decrease per correction. Default is `3`. |
| Residual export for current recovery | Extra export that must remain available before adding current beyond the rounded calculation. Default is `400`. |
| Residual export time before recovery | Seconds residual export must stay above threshold before recovery. Default is `60`. |
Without both external solar production and external home load sensors, the
controller estimates EV surplus from live Prism EV power, grid import/export and
battery power:
```text
available_power = ev_power - grid_power - battery_power_to_exclude
target_power = available_power - target_grid_export
```
With both external sensors configured, it uses the more direct house-load
formula. Prism `energy_data/power_solar` and `energy_data/power_house` are not
used for this direct calculation because on some installations they stay at
`0`:
```text
available_power = solar_production - home_load_power
if use_battery_charge:
available_power += battery_charge_available_above_reserve only when solar_production > home_load_power
target_power = available_power - target_grid_export
```
```mermaid
flowchart TD
A["Read live data
grid, EV power, voltage,
external solar production,
external home load, battery power and SOC"] --> B["Protect the home battery
reserve more power at low SOC,
reserve less at high SOC"]
B --> C{"Home load sensor
and solar data available?"}
C -->|Yes| C1["Calculate direct EV surplus
available_power = external solar - external home load
plus optional battery charge above reserve"]
C -->|No| C2["Estimate EV surplus
available_power = EV power - grid power
minus battery power to exclude"]
C1 --> D["Keep a small grid export target
target_power = available_power - target_grid_export"]
C2 --> D["Keep a small grid export target
target_power = available_power - target_grid_export"]
D --> E{"Enough surplus
for at least 6A?"}
E -->|No, autolimit active| F{"Grid import
inside deadband?"}
E -->|No, no autolimit| G["Keep Prism in solar mode
hold 6A unless current was changed manually"]
E -->|Yes| H["Convert surplus to target current
and clamp between 6A and max current"]
F -->|No| L["Respect Prism autolimit
wait for load to drop"]
F -->|Yes, cooldown elapsed| G
G --> K["Publish MQTT commands
set_current_limit and solar mode"]
H --> I["Stabilize current
deadband avoids oscillation
slow ramp-up and faster ramp-down"]
I --> J["Recover unused export
add current if export stays available"]
J --> K["Publish MQTT commands
set_current_limit and solar mode"]
```
With the default sign convention, battery discharge reduces the available EV
power in the fallback estimator, while battery charge is not counted as available
power. With both external solar production and home load sensors, battery
discharge is not treated as EV surplus: the EV receives only direct solar left
after the configured house load, plus optional battery charge power above the
protected reserve only when solar production already exceeds the house load. If
the available
power is below the minimum Type 2 current of 6A while solar balancing is
enabled, the port is kept in solar mode at 6A instead of being paused. If the
current limit was changed manually, the controller preserves that manual limit
while low surplus remains. If Prism reports autolimit mode, the controller
treats that as a wallbox protection state. It does not force solar mode while
there is real grid import above the configured deadband. Once the load has
dropped and grid import is back inside the deadband, it tries one recovery at
6A, then waits 5 minutes before any further autolimit recovery attempt.
If Prism reports paused mode or pause state, the controller treats it as a
deliberate wallbox pause, for example a charge limit reached in the wallbox/app,
and does not resume charging automatically. Change the port mode back to
solar/normal or toggle the balancing switch when you want the controller to take
over again.
If `Use battery charge as surplus` is enabled, battery charging power is counted
too, but only for the part that exceeds the battery charge power currently
reserved for the home battery. The controller also uses live battery charge
power as feedback: if the battery is still charging above the configured reserve
and grid import is not excessive, it can raise EV current gradually to bring
battery charging back toward that maximum. Because the EV current changes in 1A
steps, the battery target is approximate. Without a SOC sensor, the fixed
reserve is the configured maximum battery charge power. With a SOC sensor, the
reserve is dynamic: low SOC reserves the configured maximum charge power, medium
SOC reserves the medium value, high SOC reserves the high value, and SOC >= 95%
reserves `0 W` so the EV gets priority. This lets the car use direct solar
energy while still protecting the home battery when it is low. The EV current
follows the calculated surplus, clamped between the Type 2 minimum of 6A and the
configured maximum current.
The controller then applies a target export, a deadband, ramp limits and
residual export recovery. By default it tries to keep about `150 W` exported,
ignores changes within `150 W`, increases by at most `1A` every `15` seconds,
decreases by up to `3A` immediately, and adds `1A` if more than `400 W` remains
exported for `60` seconds.
Before raising current above the minimum from a low-surplus hold, the surplus
can be delayed by the configured ramp and stabilization settings. This helps
avoid short clouds or transient loads repeatedly changing the car current. If
surplus drops below the Type 2 minimum, the port is kept in solar mode at 6A
instead of being paused, unless Prism reports autolimit and grid import is still
above the deadband.
When enabled, the integration also exposes additional sensors for each port:
| Entity | Description |
| ------ | ----------- |
| Solar balance status | Shows whether balancing is disabled, waiting for data, paused by the wallbox, waiting for stable surplus, holding at 6A for low surplus or charging from surplus. |
| Solar surplus current | Current in amps currently available from the calculated solar surplus. |
| Stable surplus countdown | Seconds remaining before the integration starts charging automatically. |
| Calculated total surplus | Total power available to the balancing algorithm. |
| Battery power used in calculation | Battery contribution used by the algorithm. Positive values reduce EV power, negative values increase available EV power. |
| Grid power used in calculation | Latest Prism grid power value used by the algorithm. |
| Solar production used in calculation | Latest configured solar production sensor value used by the algorithm. |
| Home load used in calculation | Latest configured home load sensor value used by the algorithm. |
| Calculated target current | Final current the algorithm wants to send to Prism after deadband, ramp and recovery limits. |
| Raw target current | Current calculated directly from surplus before stabilisation. |
| Battery reserve power | Home-battery charge power currently protected by the SOC logic. |
| Target export power | Configured export buffer used by the controller. |
| Unused export power | Export still available beyond the target export and deadband; this is the power the EV could still recover. |
| Residual export countdown | Seconds remaining before unused export can trigger a current recovery step. |
| Decision reason | The current reason for the controller decision. |
The solar balance diagnostic entities also expose extra attributes including
`battery_soc`, `battery_reserve_power`, `battery_charge_power`,
`battery_discharge_power`, `solar_power`, `home_load_power`, `surplus_source`,
`available_power`, `target_power`,
`raw_target_current`, `target_current`, `unused_export_power`,
`excess_import_power`, `deadband_active`, `ramp_limited`, `ramp_direction` and
`current_limit_reason`.
## Entities
| Entity ID | Type | Description | Unit |
| --------------------------------- | ------------ | ------------------------------------------------------------ | -------------------------------------- |
| silla_prism_online | BinarySensor | Sensor to find if Prism is connected or not | |
| silla_prism_current_state | Sensor | Current state of Prism | "idle", "waiting", "charging", "pause" |
| silla_prism_power_grid_voltage | Sensor | Measured voltage from grid | V |
| silla_prism_output_power | Sensor | Power provided to the charging port | W |
| silla_prism_output_current | Sensor | Current provided to the charging port | mA |
| silla_prism_output_car_current | Sensor | Current driven by the car | A |
| silla_prism_current_set_by_user | Sensor | Current limit set by user | A |
| silla_prism_session_time | Sensor | Duration of the current session | s |
| silla_prism_session_output_energy | Sensor | Energy provided to the charging port during the current session | Wh |
| silla_prism_total_output_energy | Sensor | Total energy | Wh |
| silla_prism_error | BinarySensor | Error status (ON when there is an error) | |
| silla_prism_current_port_mode | Sensor | Current port mode | solar,normal,paused |
| silla_prism_input_grid_power | Sensor | Input power from grid | W |
| silla_prism_set_max_current | Number | Set the user current limit | A |
| silla_prism_set_current_limit | Number | Set the current limit | A |
| silla_prism_set_mode | Select | Set current port mode | solar,normal,paused |
| silla_prism_touch_sigle | BinarySensor | Goes on for 1 second after a single touch gesture | On,Off |
| silla_prism_touch_double | BinarySensor | Goes on for 1 second after a double touch gesture | On,Off |
| silla_prism_touch_long | BinarySensor | Goes on for 1 second after a long touch gesture | On,Off |
## Computed Entities
Computed entities are not directly measured from Prism but are derived from other measurements.
| Entity ID | Type | Description | Unit |
| ----------------------------- | ------ | ---------------------------- | ---- |
| silla_prism_input_grid_energy | Sensor | Total energy taken from grid | Wh |
| | | | |
| | | | |
# Setting up the user interface
## With the charger card integration
It's possible to configure the [EV Charger Card](https://github.com/tmjo/charger-card) using the configuration example [provided](https://github.com/persuader72/custom-components/blob/main/charger-card/template.yaml) in this repository
## With automations and helpers
The following four examples show how to set up a simple interface
via Home Assistant helpers (input booleans) and automations. You do
not have to use all four!
These automations and input booleans can also be used with the
EV Charger Card, though they are most useful without it.
### Start/stop charge with a switch
For now, disable Autostart on the Prism (later I will show how to keep
it enabled).
Create an "Input Boolean" called `prism_charge` (suggested icon:
`mdi:ev-plug-type2`). The following automation starts and stop the
charging process when `prism_charge` is toggled:
```yaml
alias: Prism - authorize/deauthorize
triggers:
- trigger: state
entity_id:
- input_boolean.prism_charge
id: changed_switch
- trigger: state
entity_id:
- sensor.silla_prism_current_state
id: changed_state
actions:
- if:
- condition: state
entity_id: sensor.silla_prism_current_state
state: idle
then:
- action: input_boolean.turn_off
target:
entity_id: input_boolean.prism_charge
- stop: No charging cable connected
- condition: trigger
id:
- changed_switch
- if:
- condition: state
entity_id: input_boolean.prism_charge
state: 'on'
then:
- action: button.press
target:
entity_id: button.silla_prism_set_mode_traps_auth
else:
- action: button.press
target:
entity_id: button.silla_prism_set_mode_traps_noauth
mode: single
```
### Start/stop charge with a single touch on the Prism
With the previous set up, Autostart is disabled, but starting/stopping
the charge process with the Prism key fobs does not synchronize with
the Input Boolean.
Instead of using the key fobs, you can configure another automation that
toggles the Input Boolean with a single touch on the Prism's sensor:
```yaml
alias: Prism - toggle charge after single touch event
description: ""
triggers:
- trigger: state
entity_id:
- binary_sensor.silla_prism_touch_sigle
to: on
actions:
- action: input_boolean.toggle
target:
entity_id: input_boolean.prism_charge
mode: single
```
### Same setup but with Autostart enabled
If you prefer to keep Autostart enabled or to use the key fobs, just ensure
`prism_charge` changes to on and off when `sensor.silla_prism_current_state`
becomes respectively `charging` or anything else:
```yaml
alias: Prism - synchronize charging state
description: ""
triggers:
- trigger: state
entity_id:
- sensor.silla_prism_current_state
id: changed_prism
actions:
- if:
- condition: state
entity_id: sensor.silla_prism_current_state
state: charging
then:
- action: input_boolean.turn_on
target:
entity_id: input_boolean.prism_charge
- else:
- action: input_boolean.turn_off
target:
entity_id: input_boolean.prism_charge
mode: single
```
This can be used with any combination of the previous automations.
### Switch normal/solar modes from Home Assistant
Create an "Input Boolean" called `prism_solar_mode` (suggested icon:
`mdi:weather-sunny`). The following automation keeps it synchronized
with the "solar" and "normal" modes of the Prism dashboard:
```yaml
alias: Prism - synchronize solar/normal mode
description: ""
triggers:
- trigger: state
entity_id:
- input_boolean.prism_solar_mode
id: changed_helper
- trigger: state
entity_id:
- sensor.silla_prism_current_port_mode
id: changed_prism
actions:
- if:
- condition: trigger
id:
- changed_helper
then:
- if:
- condition: state
entity_id: input_boolean.prism_solar_mode
state: on
then:
- action: select.select_option
data:
option: solar
target:
entity_id: select.silla_prism_set_mode
else:
- action: select.select_option
data:
option: normal
target:
entity_id: select.silla_prism_set_mode
else:
- if:
- condition: state
entity_id: sensor.silla_prism_current_port_mode
state: solar
then:
- action: input_boolean.turn_on
target:
entity_id: input_boolean.prism_solar_mode
- if:
- condition: state
entity_id: sensor.silla_prism_current_port_mode
state: normal
then:
- action: input_boolean.turn_off
target:
entity_id: input_boolean.prism_solar_mode
mode: single
```