There are a number of types of solar heat collecting systems, but for water heating we are concerned with a tried and proven system called flat plate collectors. Firstly though, let’s distinguish between solar electric (photovoltaic) modules which convert sunlight into electricity; solar pool heating panels, which are designed to raise a large mass of water a few degrees; and flat plate collector panels, which are designed to raise a smaller amount of water (say 300 to 600 litres) to useable hot water temperatures (of about 70 degrees Celsius). 
Construction
The typical flat plate collector consists of a glass covered box containing vertical copper pipes (called risers) embedded into a flat sheet of metal. At the top and bottom of the sheet are thicker horizontal pipes (called headers). The water from the hot water tank typically enters the bottom left hand corner of the collector casing, travels along the header pipes, up the riser pipes as it becomes hotter and exits out of the top right hand corner, where it returns back to the insulated storage tank for use when required. 

Materials
The best solar panels are made from quality components which include: copper pipes and flat copper plate; an “AMCRO” selective surface (which absorbs 95% of the available solar energy); and low iron glass (which improves solar acceptance by about 10%). 

Location
A suitable north facing mounting spot must be found for the solar panels. Generally this will be on the roof, but they may be located on a wall over a north-facing window, on a deck or even on the ground. Ideally the solar panels need to be as close as possible to, but below the storage tank. 

Roof Angle
Any angle between 15 degrees and 30 degrees is OK. On flat roofs we install a galvanised angle frame to raise the panel angle to around 25 degrees

The typical flat-plate collector is used with a number of types of hot water storage systems. Generally though, there are three main kinds of tank/panel arrangements used in domestic dwellings: 

[1] PUMPED OR SPLIT SYSTEM

A mains pressure tank is located at ground level and the solar panels mounted on the roof. With this system, when the sun shines, a pump is activated, and water is pumped through the collector plate, where it absorbs the sun’s heat. 
Advantages: The tank can be located (either internally or externally) at ground level and the panels can be above the tank. 
                      Good for roofs that do not have the strength for a close coupled system.
Disadvantages: Needs electricity to run the circulating pump and can’t be connected to a wood stove.
 

[2] CLOSE_COUPLED SYSTEMS

Both the solar panels and tank are mounted on the roof.  The panels are located just below the storage cylinder and water rises into the tank through a principle known as natural thermosiphon. 

Advantages:      Usually the most cost-effective system to install. Provides water at mains pressure. 
                           No moving parts, most efficiient system

Disadvantages: Roof needs to be strong enough to hold weight
                           Some may not like the tank on the roof

The tank is located in a roof cavity, with only the solar panels exposed on a north facing roof.  The panels must be positioned to allow for natural thermosiphon. 

Advantages:  Usually the most cost-effective system to purchase. 
                       May be connected to a wet-back in a wood stove or heater           
                       lasts long time, Looks Good!
Disadvantages: the house must be plumbed for gravity feed. 

Most new houses are plumbed for mains pressure with 12 mm copper or poly pipe running along the ground and then up to the taps. Gravity feed calls for 19mm diameter copper or 25mm poly pipes running from above the ceiling and then down to the taps. This ensures that there will not be any trapped air.

Wood Stove Connection 

One of the best ways to install a hot water system is to mount a gravity feed tank over a supporting wall, connect it up to north facing solar panels, and also connect it up to a wood stove using the natural thermosiphon principle. The tank should be located roughly equi-distant between the wood stove (or wood heater), the solar panels and the water usage points (kitchen, bathroom, laundry, etc.). Most hot water dealers will try to sell you a mains pressure system. (Perhaps they only sell one type?) Many will say gravity feed systems give pressure problems. But I recommend gravity feed constant pressure units. They tend to last much longer than mains pressure units and any concerns about potential plumbing problems can be solved with good design. 

An extra cold water header tank can be added to balance the hot and cold water pressures at the shower.
 

Q. Should I buy a solar hot water service? 

A. Every new house in Victoria and Tasmania (not just Northern states) should have solar hot water. Existing houses should change where possible (before the currently installed system breaks down). 

A. Yes, they work extremely well. Think what it’s like when you are sitting in car on a sunny, but cold and windy, winters day: you can get quite hot. A solar hot water collector works in the same way. On the whole, in Australia we are blessed with lots of sunshine. The ABC TV weather report, at 7.25pm, gives you the daily percentage saving. Even our winters (compared to other countries) are mild, and of course we have great spring, summer and autumn weather. By the way, did you know that over the summer months, Melbourne receives more hours of sunlight than Sydney! 

A. All Beasley solar systems have one or more back-up booster systems, usually: off-peak electricity, LPG, natural gas, and/or boosting from a wood fired heater or stove. 

A. No, not with a correctly sized Beasley system, given normal usage patterns. The sun can produce massive amounts of useable energy, which is stored until needed. But if you do have a few cloudy days, the electricity or gas booster system automatically heats the water to the required temperature. 

A. Yes, a wood stove or heater can be connected to a mains pressure or gravity feed solar hot water system providing the tank is above the heater. 

A. This answer depends on how your house (if built) is plumbed, your type of water supply, and whether you are likely to want to connect up to a wood heater or stove. Beasley have a large range of quality units to cater for your situation. 

A. The general rule when dealing with solar, is the bigger the tank, the better: to make the most use of the sun’s energy when available. Experience has indicated that for up to four people with normal use, 300 to 370 litres is a good size. If there are more people, go up to the next size. 

A. With most roofs, there is no problem, but make sure your roof is checked. Ceiling mounted tanks must be located over a supporting wall. Pump circulated systems are very good for houses with light roof structures.

A. Yes, for a price. While solar for hot water is worthwhile, trying to heat your house is problematic because when you need the heat in winter, solar energy is least available therefore a large number of panels is required. 

A. Certainly! Over the life of a Beasley Solar System, you would have needed to buy between 3 & 5 enamel mains pressure tanks (plus the installations).