How much solar energy available?

How much solar energy available depends on locality, cloud cover and season. This article explains how it’s measured and how to know exactly.

Yearly global solar input. Solar power is totally feasible in most areas between 50 degrees latitude (north to south).

Currently, 7000 times more solar is available than we need for power worldwide. It is 800-1000 watts for every flat square metre. Right now our solar modules 14% to 20.5% efficient. This provides 120 to 140 watts per square metre.

Solar reality is less than some expect

We can visualise solar as much as like rain, but rather measuring in a rain-gauge, we can visualise light as ‘filling’ a standard-size ‘light bucket.’  The industry calls each ‘bucket full’ as one Peak Sun Hour (1 PSH). Later in the day, the bucket may take two hours to fill (i.e. 0.5 PSH) – and so on . . .

In areas like central Australian or Arizona etc there’s 5-6 PSH/day much of the year. During a Melbourne or Madrid mid-winter, however, it will be far less. There, solar input may be as low as 1-1.5 PSH. It may also have major local variations. Googling PSH (or ‘solar input’) for your locality usually produce an answer. If not, your Meteorology Dept will advise.

You can also obtain exact data about knowing how much solar available. Establish your geographic coordinates (via Google or a good map), then open[email protected] Enter your data where shown. Open the table ‘Radiation on an Equator-pointed Tilted Surface’. (By ‘Equator’ NASA means solar modules facing south in the northern hemisphere, north in the southern.) The data is an ongoing ten-year average. It shows optimal solar module tilt angles. Five to ten degrees difference causes only minor change. The table also shows how to gain more input in winter (at the expense of summer). And vice versa. Some people make them adjustable but solar capacity is so cheap it costs little to add more if you space to locate them.

See also:

Solar energy available – how and where to go from here?

Knowing how much solar energy available indicates whether it is worth going ahead. How to proceed from here is covered in my two globally-selling solar books. Both are down-to-earth English and technically correct. My bio is at:

For all you need to know to install solar for homes and properties – buy Solar Success. That for boats, cabins and RVs is in Solar That Really Works! and Caravan & Motorhome Electrics. See also Our all solar house.

If you are interested also in RVs – see our associated