Note: 

We strongly recommend that your solar system be installed by an accredited solar installer. If this is not possible and you wish to install it yourself, the following article gives a brief overview of some general wiring principles. If in doubt, seek professional advice!

Australian Standards

There are now several hundred pages of standards that apply to solar and extra low voltage- electrical installations. The applicable primary standards are:

• AS 4509 Stand-alone Power Systems
• Part 1 Safety requirements
• Part 2 Design guidelines
• Part 3 Installation and maintenance
• AS / NZS 5033: 2005; Installation of photovoltaic (PV) arrays
• AS 4086 Secondary batteries for SPS Part 2 Installation and maintenance

Other relevant standards include:

• AS 3000 Electrical Wiring Rules
• AS 1768 Lightning Protection
• AS 1170.2 Wind Loads
• AS 4777 Grid Connections of Energy Systems via Inverters
• AS 3001 Electrical wiring rules for mobile applications

Cable Size

A common fault is using undersized cables. Make sure that each cable is rated to carry the maximum amount of continuous current.
Cables should be sized so that the voltage drop is not greater than 5% (0.6 volts for a 12V system).
DC cables should be physically separated from any AC wiring.

Cables should be protected in conduit if exposed to the elements, risk of mechanical damage or attack by rodents. 

Fusing

Every circuit should be protected by a fuse or circuit breaker. Where a smaller cable is connected to a larger cable the fuse should be sized to protect the smaller cable. Read more about fuse sizes.

Label your breakers so you can identify them in the future.

Batteries

According to Australian Standards batteries are to be inside a ventilated, lockable and vermin proof box. The terminals should be protected with terminal covers so that explosions won't occur if a screw driver or something falls across them. Flooded wet cell batteries should also be installed on a battery tray (to contain acid leaks).

There should only be one cable going to each battery terminal. Spaghetti junctions at the terminals should be avoided and multiple connections should be made using links inside of a distribution box. Read more about Battery Enclosures.

Solar Panels

a) These should point north (in the Southern Hemisphere) at an angle suggested by your solar designer. This will generally be at a 'best yearly average'. However, depending on your loads you may wish to maximise your solar input for either summer or winter conditions. You can get some idea of suitable angles for Australia by looking at the solar radiation figures for some selected locations in the drop down menu for Solar Radiation Figures.

b) Make certain that water won't creep along your cable to your solar panels into the J box at the back. If the cable is coming above or horizontal to the J box, have it loop down first below the J boxes so water can drip off it first.

c) Make certain your panels are securely bolted or fixed to your roof or other structure so they don't blow away in a storm.

d) You might like the appearance of your panels flat on your roof. We generally prefer to see them at about 100 mm above the roof to help keep them cool and to avoid any build up of leaves or vermin under them. Remember, one day you may need to access the wiring for service or testing purposes. More information on mounting & ventilation of solar panels.

e) Your panels, like all other circuits, should be protected by fuses or circuit breakers. One day in the future you will probably notice a decrease in solar input performance. This will probably be due to a poor connection or failing batteries. In very rare circumstances a solar panel could develop a problem. Fault finding when there are multiple panels can be a time consuming task. We suggest you have at least a separate circuit breaker for each half of your solar panel array. By installing extra circuit breakers you can turn off sections of your array and observe the difference it makes to your solar input. If there are no observed differences, any performance decrease is now most likely to centre around the battery connections.

f) Check your wiring first with a voltmeter before turning your circuit breakers and appliances on. A 12V battery should read a voltage of 10 to 15 volts depending on your battery state of charge. If everything appears to be correct, turn on your lights and other loads. If some lights go dim when other loads are turned on this is probably an indication of poor connections, undersized cables or poor battery condition.