Openai/68430895-45e8-8003-b6ec-1ea2c7c9ddf6

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gpt-4o

User: Attempting to quantify solar heating.

Attempting to quantify solar heating. I have two solar coils, currently running in parallel, to heat the pool. I am monitoring solar, pool, and ambient temperatures, along with the lux (Lx) of the sun. It's fascinating to watch, but I need to figure out how to quantify this data so I can correlate solar water flow with pool temperature change. Hardware: esp32 w/two temperature probes, Ambient Weather Station for air temp and solar, and Home Assistant for monitoring. Ultimately, I would like to have HA control the pump (including flow) to maximize the heating.

Assistant: This is a great project, and you're collecting the right kind of data to start quantifying solar heating performance.

This is a great project, and you're collecting the right kind of data to start quantifying solar heating performance. Here's a roadmap for how to correlate solar water flow with pool temperature change and eventually control the pump via Home Assistant (HA):

1. Define Key Metrics

To quantify performance, focus on:

• ΔT_coil = Outlet temp - Inlet temp of solar coil (temperature gain from solar)
• Flow Rate = Liters/minute or gallons/minute
• Solar Power (W/m²) = Use LUX and temperature to estimate this
• BTUs or kWh Added to Pool = ΔT_coil × flow rate × conversion factor

2. Estimate Energy Input

You'll need to approximate energy gained by the pool:

Q = m × Cp × ΔT
Where:
* Q = heat energy (in joules or BTU)
* m = mass of water (kg or gallons × 8.34)
* Cp = specific heat capacity of water (4.186 J/g°C or 1 BTU/lb°F)
* ΔT = temperature change of water across the coil

If you can measure or estimate flow, even roughly, this formula gives you the energy delivered to the pool.

3. Use Lux to Approximate Solar Irradiance

LUX isn’t perfect for thermal solar but you can use a rough conversion:

1 W/m² ≈ 0.0079 lux (for sunlight)
So: solar_irradiance = lux × 0.0079

This lets you estimate available solar power and correlate it with heat gain from the coils.

4. Correlate Variables

Log this data:

• Time
• Solar irradiance (from LUX)
• Ambient temperature
• ΔT across the solar coil
• Pool temperature change
• Flow rate (or at least pump ON/OFF state)

Plot:

• ΔT vs solar irradiance
• Pool temp vs runtime
• Energy gained vs time of day

5. Home Assistant Automation

Once the correlation is clear, build an automation in HA:

• Turn pump on/off when: - Solar irradiance > X - ΔT across coil > Y - Ambient temp or pool temp below Z
• Use flow control (if supported) to adjust speed for optimal ΔT

You can use Node-RED or HA's built-in automation engine to make logic-based decisions.

6. Optional Add-ons

• Add a flow sensor (e.g., YF-S201) to ESP32 to get actual flow rate
• Use MQTT or ESPHome to publish data to Home Assistant
• Integrate a basic predictive model (even Excel or Python to start) for smarter automation

If you want help building the calculations, creating automations, or integrating any specific sensor into HA, let me know — I can help you write the code or YAML.