Evacuated Tube Solar Hot Water Systems for Home use Calculator

Evacuated Tubes for Solar Hot Water
  • What are the advantages of evacuated tube solar hot water?
  • Is it suitable for your location and hot water consumption?

Calculate your hot water consumption and expected solar hot water creation over its lifetime in your location.
Results in under 5 minutes.

Evacuated Tube Solar Hot Water Advantages

  • Less weight on roof. Can be less than 40 kilograms.
  • Smaller in area on roof compared to alternatives.
  • More efficient with different angles of the sun.
  • Hot water tank is on the ground. Less issues with storms.
  • Evacuated Tube quantity and tank size can be varied to suit location.
  • Easier to place on the roof than a single large heavy solar collector.

Evacuated Tube Solar Hot Water Disadvantages

hot water shower
  • Small circulation pump needed to move water between tank and solar collector when heating. E.g. 30 watts.
  • Solar hot water can provide 60-80% of your hot water needs
  • Solar system needs an electronic controller consuming about 5 watts.

Solar Hot Water Plan

  1. Confirm you are operating with hot water efficient tap-ware.
  2. Calculate your hot water consumption
  3. Enter your current power cost per kWh
  4. Use link to work out the solar radiation available in your location of the world
  5. Click Get Results button and review the findings
  6. Look at the return of investment values. At what installed cost is solar hot water viable?

Hot Water Efficient Tap-ware

Replace a shower head for a water efficient one and Save 55% in water and associated heating costs.
Install tap aerators and Save 75% in water and associated heating costs.

Hot Water Use Consumption Calculation

Fill in the first 2 columns. Use 0 if not applicable.

Showers Minutes Proportion Hot Water (0-1) e.g. 0.5 Litres / year
Hand washing and
dish washing
Minutes Proportion Hot Water (0-1) e.g. 0.5 Litres / year
Baths
(60 litres)
Quantity Proportion Hot Water (0-1) e.g. 0.5 Litres / year
Dishwasher
(25 litres)
Quantity Proportion Hot Water
0 = cold water, 1 = hot water
Litres / year
Totals Litres / year

Add power costs and solar radiation values

Power Cost in Dollars per kWh example 0.18

Your local average daily Solar Radiation
World Map Solar Radiation (kWh/m2/day)World Map Solar Radiation small

Press button to fill in results column

Hot Water and Energy Use Results

Parameter Water Results

Total Hot Water Use for day in litres.
This is useful for calculating hot water storage size needed.


Total Hot Water Use for year in litres


Hot water power consumption per year estimate (kWh)
not including reheating

Electricity hot water costs per year ($)

Electricity hot water costs per 20 years ($)

Potential local Solar Hot Water savings over 20 year (kWh)
Also Potential CO2 reduction in kilograms for coal electric power

Potential local Solar Hot Water savings over 20 year ($)

Return on Investment

At what installed cost does solar hot water seem economically attractive?

Installed Cost 1000 2000 3000 4000 5000 6000 7000 8000
Yearly Return on investment %

Solar Hot Water Considerations

  • A larger water tank can take compensate for a cloudy day causing lower solar water heating.
  • Size the solar collector for your hot water consumption and average daily solar radiation.
  • The best aspect for solar panels is facing the equator (Northern hemisphere face south, Southern hemisphere face north).
  • The ideal pitch angle equals to your location latitude.
  • Special considerations are needed in frost or snow areas.
  • Instantaneous gas heating can be used after the hot water tank to make up any shortfall in water temperature.
  • Become familar with any government rebates available. E.g. $1600 is available in Australia.
  • Renewable Energy Credits (RECs) can be sold after installation of solar hot water in some countries (~$1000-$2000).
  • Australian $1600 Solar Hot Water Rebate
  • List of solar hot water systems with REC rebates
  • Solar zones in Australia that alter REC rebates
  • Up to $10000 green loans with 4 years internet free This is available in Australia to help pay for e.g. solar hot water
hot water energy consumption and load going up or down Does this type of hot water system suit you
Where is your hot water energy consumption going? Does this type of Solar Hot Water System suit you?


Calculate all possible energy efficient activities and see which ones are easiest to implement and get the best return on investment.