Where solar can realistically be used depends on the need and motives, but generally where solar can realistically be used is in any temperate climate at latitudes numerically lower than 38 to -40 degrees. Technically it becomes there’s at least 2.0 Peak Sun Hours (PSH)  a day. That amount would be typical for a sunny Tasmanian/New Zealand/Spanish mid-winter. Solar really comes into its own from 3.5 PSH onward and that is typical across much of Australia, Europe and the USA except in mid-winter. It’s more or less anywhere that’s no green on the map below.

SOLAR world map web

This map shows typical average yearly daily input in PSH. Technically 1 PSH is an irradiation of 1000 watts per square metre. Map: original source unknown.

Apart from mid-winter months, most of central Australia, and central America and India has about 6.5 PSH a day. As solar panels (in 2015) are 14%-20.5% efficient in turning sunlight into electricity,1000 watts of solar panel in any such area will have a daily average of 140-205 watts an hour – about 910 watt/hours a day, and 1335 watt/hours a day.

The Peak Sun Hours for almost anywhere in  the world can be found by Googling the name of the closest big town plus Peak Sun Hours, or from met offices worldwide. If it does not show peak sun hours it is likely to be in the number of 1000 watts per square metre.

Our books Solar Success and Solar That Really Works! show Peak Sun Hours for Australia’s mid summer and mid winter. Successful Solar Books however can provide solar information for anywhere in the world (and in plain English!). It shows the Peak Sun Hours per month for your location (averaged over 10 years). It also provides the optimum angles for the solar modules. The cost is A$175 and includes a free copy of Solar Success (post paid). For details please email [email protected] (payment is via credit card or direct bank transfer). 

Solar Success covers every aspect of designing, installing and using solar in homes and properties. Solar That Really Works! is for boats, cabins, camper trailers, caravans and motor homes. 

If you found this information useful you will find all you need to specify, design, build and install stand-alone solar systems of any size. And from a writer/engineer who has done this himself many times. See also Building Your Own Solar Power System, All Solar House, Solar Equipped RVs