Thermal Solar Controller

We have a evacuated tube solar water heater. For many years it has used a simple temperature controller to measure temperatures and then switch the pump on and off. However lately the units LCD has gotten to the point, no matter where you hit with a hammer it still doesn't work.

This started off as a simple replacement but as usual it has taken on a life of its own. I mean the original works ok but we always forget to boost when cloudy weather is forecast. It's very hot here for many months of the year so we normally just turn off the booster and forget about it, until the first cold shower.

Almost the same cast of sensors

There was originally two NTC temp probes on the water tank that I have replaced with Dallas ones (max of 125C) . The PT1000 on the solar collector has to stay as it gets a wee bit warm up there after the water boils. So I've used an off the shelf ADC board for this sensor.

OpenWeather

It was suggested to integrate wind speeds into my solar tracker by several Hackster users, This sounded easy except the gettering around to doing it bit. So determined to make a start I thought why not try it on this project first. OpenWeather is a platform that allows you to get weather information for any point on the globe. It responds to an API request with a JSON datagram via http or https. You then "simply" parse this and presto.

So after requesting an API key and trying it out in the web browser I was armed with items for the next step.

Taking the long shortcut

Thought I'd save some time but looking at someone else's project/work (which was actually for an ESP32), this approach usually works for me ("maintenance coder" in the bio). Anyhow after two frustrating nights I gave up and started to read the manual for ArduinoJson , in hindsight this should have been my first stop. The documentation at the website is nothing less than brilliant. Including the assistant which codes samples and works out memory based on your JSON input. So a tip of the hat for Benoît Blanchon.

The only issue I had was the v6 lib would not compile with my ESP8266. The v5 was fine so as usual , path of least resistance I went with v5. I wasn't really in the mood for working out why, the library looked like it contained conceptual levels of abstraction way above my pay grade. So I was content with coding that seemed to run first time once we had actually deployed it correctly.

Emails in Microcontrollers

Relatively new thing for me. This is only my second project to use them. While working on an Allen Bradly PLC I had the sudden thought I should try and use some of the same emailed alarm concepts. So I have been working towards that. The project now has emailed alarms so I can brace myself for the cold shower that night or warm myself up beside the fire before leaping into what I know will be cold water.

The Board

Once again I just picked something I could buy off the shelf. Maybe I'm getting lazy but I do have a thing about not reinventing the wheel unless your going to do a good job of it. Anyhow the software is designed to operate with almost any ESP8266 relay board so take your pick and configure / wire it up accordingly. The relays can be mapped to any pin and are configurable active high or low in software. I did go for a 10-30 Volt DC on board power supply figuring 24V DC was bound to make a appearance in the bigger picture at some point. I do want to integrate this with my ESU to utilise "waste/unusable power" at some point.

WEB UI

There is the my usual set of tools in th UI