Solar Thermal Collector Mk1 General Notes Page

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Solar Thermal Collector Mk1 Experiment 1


The goal of this project is to get me started with building actual energy collection devices. Ideally this project should take the water source and achieve elevated temperatures.


A simple design was decided upon for my first solar thermal project. A hot water pump will take water from a source (bucket) and pump it through rubber tubing that goes through empty/cleaned 2L bottles and deposit the water back in the source.

After deciding on using 8 2L bottles the length was determined to be around 30 feet. This allows ~2 feet per bottle, a foot between each bottle and ~2-3 feet between the bottle array and the water source (bucket)

Top View of Whole System
Top View of Whole System

Parts list/Budget

Item Cost
Temperature Sensor $6.99
5 Gallon Bucket $9.95
Hot Water Pump $21.98
Plastic/Rubber Tubing $31.39
48 Count AA Batteries $12.09
8 Recycled 2L Bottles $--.--
Total Cost $82.40

Parts Research

Temperature Sensor

  • There are different thermometers available that could meet this purpose
    • Fish tank thermometer
    • Cooking/grilling thermometer
  • Going with a grilling thermometer because it will probably be better suited for elevated temperatures that I plan to achieve with the thermal collector system

Hot Water Pump

  • Looking at 12V water pumps because they're smaller and more economical
  • Going to need to find a way to power the pump
  • It is unclear what size the included brass couplers are

Rubber Tubing

  • Guessing I'll need 30 feet (see assumptions/design)
    • Lots of tubing only available in 10ft, 25ft, 50ft lengths
  • Decided on a 1/4th in inner diameter tube with 20 extra feet just in case
    • Hopefully the tube will stretch over the hot water pump opening
    • Would be cheaper to buy new brass couplers instead of new tubing if it doesn't fit

Power Supply

  • Decided it'd be cheapest to just use the 8 AA battery holder to supply the 12 volts required by the heat pump
  • Might long run end up being more expensive if the batteries do not last for long periods of time


The hose doesnt fit the brass couplers that came with the pump

Putting holes in the bottle caps

First Run

Temp change chart

Time (min) Temperature (deg C)
~0 25.8
~15 28.2
~30 29.8
~45 31.2
~60 32.5


Bucket Array
Bottle Array
Bottle Close Up
Hot Water Pump
Battery Pic

Ideas for Improvement