Solar on the roof

The angle advantage

In Australia, you want panels facing roughly north and tilted between 15 and 30 degrees from horizontal (depending on your latitude). A skillion roof with a modest pitch gives you that angle for free, without a tilt-frame or adjustable mount. Set the high end of your shanty toward the south when you build it -- or at least away from due north -- and the low end faces the sun.

This is the main structural decision to get right at the time you plan the shanty. The direction the slope faces determines how good your solar resource is. In South East Queensland, facing panels north-northeast to north-northwest covers the good part of the range. You do not have to be exact, but you want to avoid east or west-facing slopes if solar is a priority.

Fixing panels to corrugated steel

The standard frugal method is panel clamps that hook over the corrugation ridges. These need no drilling through the roof sheet -- they grip between the corrugations and let you bolt a rail or frame to them. If you are using standard aluminium framed panels, these clamps hold the frame directly. Keep the panels close to the roof surface so wind cannot get underneath and generate lift.

If you drill through the sheet for any reason, use roofing screws with neoprene washers and seal around the penetration with roofing silicone. Any unsealed hole in a corrugated roof will leak eventually.

Wiring it down

Run your DC cable from the panels down through a conduit on one of the posts. A length of 20 mm UV-rated conduit clamped to the post keeps the cable off the roof surface and protects it from sun and animals. Bring it into whatever enclosure you have for your charge controller -- typically a weatherproof box mounted on a post or on the wall of your existing shed underneath.

Use appropriately sized DC cable for the run length. Voltage drop in DC systems is a real cost -- thin cable on a long run wastes power as heat. See the electronics basics page for how to size cable for your system, the panels page for sourcing salvaged panels, and the MPPT page for charge controller options.

Battery storage underneath

The shanty is a natural home for battery storage: it is shaded (batteries do not like heat), ventilated (off-gassing from lead-acid batteries wants somewhere to go), and separate from your house. A weatherproof enclosure on the ground under the shanty, close to the charge controller, keeps cable runs short and puts heavy batteries where they are easy to work on.

The batteries page and the system design page have more on what to buy and how to put it together.