TuftedPuffin.co.uk

Introduction

We've recently had installed a solar thermal system to provide cheap hot water.

The installation was done by a reputable local form. The installation of temperature monitoring sensors was done after the installation, hence temperature monitoring of the collector itself is not available.

Installation

The solar collector consists of ?? Evacuated Tubes, covering an area of 3 Sq Metres.

The collector is mounted on the main roof of the house facing S20E. The collector panel is mounted between 2 chimneys so is in partial shade for some parts of the day.

As part of an earlier bathroom re-vamp project we had already installed a 300 litre hot water cylinder with an extra heating coil, ready for a solar installation.

The collector panel is connected to the water cylinder via a loop of 10mm copper pipe. A pressure vessel allows for expansion of the water in the loop. A small pump is used to move water around the loop.

A controller is connected to a temperature sensor in the collector panel and a temperature sensor on the return pipe of the solar heaing coil of the cylinder. The controller will start the pump if the temperature at the collector is greater than the cylinder temperature plus some margin. This margin is configurable.

The controller provides a readout of the current temperature at the sensors.

The controller also keeps track of the total number of running hours of the pump. This is the only metric available from the system.

A Schematic of the installation would look something like this:-

WHY

Once the system had been installed I realised that I didn't really know how effective it was being, and further more had no way of monitoring it's performance.

I wanted to be able to tell when it had been working and maybe calculate how much energy it was contributing.

I therefore decided to install some kind of system to enable me to monitor it's day to day performance.

The first step was to decide on how to monitor the system, the sensors to use and how to log and report the data. OneWire