Portable 230V/12V petrol & diesel off-grid generators have long been popular, with cheap (~$1 per watt or less) offerings in most hardware stores.

The Jaycar MP-4552 CIS self-contained solar lighting system is a much better proposition. It's much lighter, MUCH cheaper to run (energy from the sun is free until the Government works out a way to tax it!). With care, the supplied battery will last for years and even then they aren't too expensive to replace. We're very impressed with the CIS solar side of the kit; it's a pity that it is somewhat let down by poor-quality lighting fittings. Still, these are replaceable at relatively low cost!

Aside from their use by farmers and tradesmen, in many remote regions the evening hum of the lighting generator is still almost as ubiquitous as a campfire.

However, generator storage and maintenance hassles, noise, fumes (and of course the need to purchase, deliver and store costly fuel) mean TCO (total cost of ownership) of off-grid systems are increasingly expensive.

Generator economics, even with remote regions facing fuel costs approaching $2 a litre, may seem "good value" and convenient against mains electricity at up to 20 cents per kW h "unit" (and more – see last month’s "Publisher’s Letter"). But are they good value?

Each litre of petrol has a calorific value of around 36MJ (diesel is slightly higher but most small generators are petrol-driven). As 1kWh = 3.6MJ (1000x60x60), this means a litre of petrol equates to some ten electrical units. With even the best fossil fuel generators only about 40% efficient in utilising this energy (most being wasted as heat), the electricity generated equates to a more costly 50 cents per kWh. Fuel storage and security, generator maintenance and eventual generator replacement need factoring in as well.

In the Australian outback, the vast Pacific expanses and in "off the beaten track" New Zealand, a generator may still be crucial for running power tools and refrigeration. But for modest lighting and perhaps battery charging needs, it increasingly makes no sense to inefficiently use fossil fuels when alternatives abound.