Many countries are installing solar hot water systems

AUSTRALIA. NewSouthWales and Queensland. Electric hot water cylinders cannot be used in new houses. Solar hot water systems with gas backup if required.
India more solar hot water

Spain Solar units everywhere

USA Tax credits up to 30% for solar equipment including labour .

ISRAEL Solar hot water units on every rooftop.

UK All homeowners can install solar electricity panels or solar hot water panels or windmills without needing to get planning permission, as long as there is clearly no impact on others.

GERMANY Germany added an extra 20.6 gigawatts of solar power and solar hot water enough to supply the needs for 5 million homes. 45,000 new jobs have been created in the solar sector. Good progress towards their target of 20 percent renewable by 2020.


Solar hot water in Kenya

Kenya has regulations regarding solar hot water for all new houses using more than 100 litres of hot water per day.

There are two main types of solar collectors.

(A) Flat panel collectors. These are a flat panel of copper with a number of copper pipes brazed to the flat panel. Size is around one meter by two meters When faced to the sun the flat panel heats water in the copper pipes which then moves into a hot water insulated storage cylinder. These flat plate collectors have been used for years. They perform well but can develop leaks because every day there is expansion and contraction of the pipes and the collector panel The flat panel collector only heats water when the sun is shining. Scale from hard water can block the copper pipes.

(B) Solar glass tubes. These are glass tubes made from very tough
glass and have a vacuum inside
. The tubes collect heat from the sun and can heat water even on an overcast day and keep the water hot for many hours. Tubes for houses are 1.8 meters long and 58 mm in diameter. The number of tubes usually starts from 10 tubes up to 30 tubes but can be many more tubes for one installation if more hot water is required. Solar glass tubes can be of several types which may be full of water or have no water inside them. These solar glass tubes are outstanding technology and used all around the world.


There are two main types of glass tube solar hot water units available


Integrated (all in one) or split unit. (panel + cylinder)



A low cost unit
using THERMOSYPHON TUBES, not suitable for connection to household hot water cylinder. Not suitable for freezing areas. This basic no frills model is not very expensive and used by the millions in every hot country. These units have solar tubes full of water. They are made in huge numbers for hot climates Africa, Middle east, Malasia, Indonesia, China to collect hot water during the day and use at night.
Prices start at 50 US dollars for a unit with 100 litres of water and 10 solar tubes with a stand ex China.


Second main solar type is the Split system with separate hot water cylinder using HEAT PIPE tubes. Pumped system

There is no water in the heat pipe tubes. They collect heat and use a heat pipe to put heat into a manifiold which conducts heat into the hot water cylinder which is inside the house.

Ok for areas with frost.

This solar hot water type is where the collector assembly is on the roof
(or on the ground ) and the hot water pumped to your hot water cylinder

The split system using heat pipe tubes is a well developed solar hot water installation used all over the world and is a simple and reliable system to heat water with very few problems

The collector must be installed at an angle of between 25 degrees and 90 degrees to the horizontal to make the heat pipes work.

For roof fitting a permit from your council may be required. Usually there is a fee for roof mounting. On steep roof safety precautions should be taken. You do not need to put a split system on your roof . You can use the stand usually provided and mount the collector on the ground or on posts. You need a pump and a controller and one or two temperature sensors. Manufacturers say these tubes work down to minus 20 degrees centigrade. The tubes are dry there is no water in them and you can remove tubes to reduce Summer overheating. The system still works with some tubes removed.
These systems need a pump to move the hot water from the solar collector to the hot water cylinder. The pump can be run from house electricity or a small solar panel.
It will work at mains water pressure or low pressure
Heat pipe tubes is used all around the world and are a very well established solar hot water technology. It is a robust and simple system that works very well.

Prices start at US $250 ex China which includes 12 tube solar collector with heat pipe tubes and includes the 200 litre hot water cylinder which has back up electric element in case there is not enough solar energy to bring the hot water temperature up to 60 degrees centigrade every day to avoid legionaires disease.


Glass tube diameters are usually 58mm diameter and 1.8meter long.

THERMOSYPHON tubes ... Water inside the tube
Heat pipe tubes ................... No water in the tube


Water filled collector tubes are good and efficient at collecting solar heat and are cheap
The tubes are cold to the touch
Being filled with water they can freeze.
If a tube breaks all the hot water in the cylinder pours out and a new tube must be fitted. These tubes are not suitable for freezing conditions.


Tubes are dry there is no water in the tubes.
Tubes do not leak. Tubes are cold on the outside. They are easy to put tubes in or take them out. If a tube breaks the hot water in the cylinder does not pour out
If a tube breaks there is no dangerous chemicals that leak out.
Manufacturers say they are ok down to minus 20 degrees centigrade so good for area with frost
If a tube breaks very very unlikely unless caused by misuse the solar unit continues to function no hot water spills out
You can remove tubes if the solar unit is overheating in a very hot climate.

Dry HEAT PIPE tubes are used all over the world. They are dry tubes they do not contain hot water and almost nothing can go wrong with them.

In addition to being very good to collect sunshine to make solar hot water these glass solar tubes are very good to cook food




The stand stainless steel bolts rust. Put some grease on them or replace
Painted steel stands rust. Treat the rusty parts with a rust converter and paint.
Stainless steel stands rust. Not much but some.

Richard Williams