Hey everyone! I wanted to share my recent project on optimizing HVAC efficiency using surplus solar energy. It’s been a fascinating journey, and I’d love to hear your thoughts and experiences too!
The Goal:
My aim was to synchronize my air conditioning system with the surplus solar energy generated during the day. This not only helps in reducing energy costs but also ensures a comfortable indoor environment, especially during hot summer days.
The Setup:
I utilized the DRED interface in my air conditioning system, which allowed me to regulate power consumption through a setup of four relays. The idea was to adjust the air conditioning setpoint based on the excess solar power available. If there’s too much demand, I increase the setpoint to reduce power usage. Conversely, if there’s abundant excess solar energy, I lower the setpoint to increase consumption by the air conditioner.
The Formula:
I developed a formula to calculate the setpoint: SetPoint = ExternalTemp - (CoolingFactor / ExcessSolarPower). The CoolingFactor, measured in watts per degree Celsius (W/°C), varies depending on the household’s specific conditions like insulation quality and thermal mass. For my setup, a CoolingFactor of 1500 W/°C has worked effectively.
The Automation:
I implemented an automation that adjusts the air conditioner’s setpoint in response to changes in excess solar power. It also considers the state of charge of the battery, ensuring the battery is prioritized for charging. Once the battery is fully charged in the afternoon, the air conditioner then receives the majority of the power, effectively reducing indoor temperatures.
Challenges and Learnings:
Initially, I experimented with including InternalTemp as a variable, but it appeared to have a negligible effect on long-term power usage. Balancing battery charging with air conditioning usage was another challenge, but the automation has helped streamline the process.
I’d love to hear about others’ experiences and methods in managing air conditioning with Home Assistant in similar scenarios. Have you tried optimizing HVAC with solar energy? What strategies have worked best for you?
Let’s keep the conversation going! 
