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Solar Water Heating

Solar Collectors

A cleaner, greener energy future today

Solar water heating (SWH) is now the BEST green investment you can make for your home.

SWH basics

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Rooftop PV

Generate electricity from the sun on your rooftop, today

Enhance your energy security & reduce your energy costs with solar photovoltaics (PV) 

Solar PV basics

Energy Efficiency

Energy Efficiency in the Home

The are better things to spend your money on than electricity

Make your home or office more energy efficient with these simple steps & save

Energy Efficiency Basics

Sizing a Solar Water Heating system

Sizing a Solar Water Heating system

When going solar, the last thing you want to do is to under-size a system leading to situation that does not deliver according to one's expectations. The table below provides a guideline based on potable hot water consumption. A soft science approach is to start at the temperature that one washes or showers at being 40 ºC. A good 5-minute long, high pressure shower at 20 litres per minute amounts to 100 litres per person at 40 ºC . Two people will therefore use 200 litres. In order to get 200 litres of 40 ºC hot water, a solar water heater of 150 litres will provide this but it needs a Q performance of at least 17.5 to 20.5 at 20MJ /m2 per day.

 System & Household SizeDaily Requirement of Hot (40 ºC), Potable Water 
      Thrifty Usage Average Usage
People: human iconhuman icon   140 litres 200 litres
SWH System Size:150 litres ‘Q’ Factors Required: 17.5 20.5
     
People: human iconhuman iconhuman icon    210 litres 300 litres
SWH System Size:200 litres Q’ Factors Required: 25 30
         
People: human iconhuman iconhuman iconhuman icon    280 litres 400 litres
SWH System Size:200 or 300 litres ‘Q’ Factors Required: 34 40
         
People: human iconhuman iconhuman iconhuman iconhuman icon    350 litres 500 litres
SWH System Size:300 litres ‘Q’ Factors Required: 42 50
         
People: human iconhuman iconhuman iconhuman iconhuman iconhuman icon    420 litres 600 litres
SWH System Size:300 litres ‘Q’ Factors Required: 50 60

Check with your supplier both the size and the power output of the system at 20 MJ. Too small or not powerful enough and you will always be using the electrical back up, and will be disappointed by the electrical savings. This is one area where size does matter!