oh, and while Iâm at it. I also want to share how I implemented my strategy for charging and discharging my battery for âoptimalâ savings on my energy bill whilst on a dynamic contract with Tibber. The aim of the strategy is to use the battery to save on my energy bill and doing so see if the costs of a battery can be earned back. Any energy savings and net-congestion resolving achieved are nice bonusses, but not my primary goal.
I think that for me to save money, I should charge the battery when prices are low, and discharge when the prices are high. Since with Tibber I get paid exactly as much for my energy delivered as I pay for energy taken from the grid, it doesnât matter -towards my energy bill goal at least- if or how much my solar panels are pushing out: at any time if I charge the battery from the grid, I pay exactly as much as I lose from solar energy not being delivered onto the net. i.e. I do not need to use the current solar production in my decisions whether to charge or discharge. Only the current price is important in that decision.
The Tibber integration exposes the current price for both energy consumed and produced as a single sensor, and this gets updated once every hour. The price includes all taxes, so this can easily be used to switch off my solar panels when the price goes below zero, and back on once it goes above zero again; this is however a story for another day. The Tibber integration also provides on this sensor an attribute âprice levelâ. This has values ranging from âVERY_EXPENSIVEâ through âEXPENSIVEâ, âNORMALâ, âCHEAPâ to âVERY_CHEAPâ. I couldnât be much bothered at exactly which tariff the level changes, but I considered it to be a nice starting point to control the switches on my virtual battery. I decided to use this level as follows:
- âVERY EXPENSIVEâ : enable âForce dischargeâ
- âEXPENSIVEâ : enable âDischarge onlyâ
- âNORMALâ : default behavior (depending on excess solar power)
- âCHEAPâ : enable âCharge onlyâ
- âVERY CHEAPâ : enable âForce Chargeâ
I created the below automation that implements this strategy. Further optimisations could be achieved by taking into account a prediction on how long it will take to fill the battery to 100%; i.e. there could be more favorable times for charging/discharging the battery, based on the time it takes to reach 100 and 0% SOC (state-of-charge) and the future prices known up to 24 hours ahead. This script does not do any such calculations, it just charges when price is low, discharges when the price is high, and speeds things up as fast as my battery can go when the price is very high or very low.
Please let me know what you think of itâŚ
alias: "Battery sim: DIY 100K"
description: ""
trigger:
- platform: homeassistant
event: start
- platform: homeassistant
event: shutdown
- alias: When automations are reloaded
platform: event
event_type: automation_reloaded
- platform: state
entity_id:
- sensor.rozemaatjes_electricity_price
attribute: price_level
condition:
- condition: template
value_template: >
{% if is_state_attr('sensor.rozemaatjes_electricity_price', 'price_level',
'VERY_EXPENSIVE') %}
{{ not (is_state('switch.battery_sim_diy_100k_force_discharge', 'on')
and is_state('switch.battery_sim_diy_100k_discharge_only', 'off')
and is_state('switch.battery_sim_diy_100k_charge_only', 'off')
and is_state('switch.battery_sim_diy_100k_force_charge', 'off'))
}}
{% elif is_state_attr('sensor.rozemaatjes_electricity_price',
'price_level', 'EXPENSIVE') %}
{{ not(is_state('switch.battery_sim_diy_100k_force_discharge', 'off')
and is_state('switch.battery_sim_diy_100k_discharge_only', 'on')
and is_state('switch.battery_sim_diy_100k_charge_only', 'off')
and is_state('switch.battery_sim_diy_100k_force_charge', 'off'))
}}
{% elif is_state_attr('sensor.rozemaatjes_electricity_price',
'price_level', 'CHEAP') %}
{{ not(is_state('switch.battery_sim_diy_100k_force_discharge', 'off')
and is_state('switch.battery_sim_diy_100k_discharge_only', 'off')
and is_state('switch.battery_sim_diy_100k_charge_only', 'on')
and is_state('switch.battery_sim_diy_100k_force_charge', 'off'))
}}
{% elif is_state_attr('sensor.rozemaatjes_electricity_price',
'price_level', 'VERY_CHEAP') %}
{{ not(is_state('switch.battery_sim_diy_100k_force_discharge', 'off')
and is_state('switch.battery_sim_diy_100k_discharge_only', 'off')
and is_state('switch.battery_sim_diy_100k_charge_only', 'off')
and is_state('switch.battery_sim_diy_100k_force_charge', 'on'))
}}
{% else %}
{{ not(is_state('switch.battery_sim_diy_100k_force_discharge', 'off')
and is_state('switch.battery_sim_diy_100k_discharge_only', 'off')
and is_state('switch.battery_sim_diy_100k_charge_only', 'off')
and is_state('switch.battery_sim_diy_100k_force_charge', 'off'))
}}
{% endif %}
action:
- metadata: {}
data: {}
target:
entity_id: switch.battery_sim_diy_100k_force_discharge
action: >-
switch.turn_{{ 'on' if
is_state_attr('sensor.rozemaatjes_electricity_price', 'price_level',
'VERY_EXPENSIVE') else 'off' }}
- metadata: {}
data: {}
target:
entity_id: switch.battery_sim_diy_100k_discharge_only
action: >-
switch.turn_{{ 'on' if
is_state_attr('sensor.rozemaatjes_electricity_price', 'price_level',
'EXPENSIVE') else 'off' }}
- metadata: {}
data: {}
target:
entity_id: switch.battery_sim_diy_100k_charge_only
action: >-
switch.turn_{{ 'on' if
is_state_attr('sensor.rozemaatjes_electricity_price', 'price_level',
'CHEAP') else 'off' }}
- metadata: {}
data: {}
target:
entity_id: switch.battery_sim_diy_100k_force_charge
action: >-
switch.turn_{{ 'on' if
is_state_attr('sensor.rozemaatjes_electricity_price', 'price_level',
'VERY_CHEAP') else 'off' }}
mode: single
