Australia to build 20 Megawatt Solar Farm in Canberra that may Provide 3.6 Megawatts of Useful Electric Power

Posted by PITHOCRATES - September 8th, 2012

Week in Review

Australia is working hard to save the planet.  They’re building a new solar farm that will be the biggest in all of Australia.  Allowing the environmentalists to feel good.  But it will do little if anything (see Canberra to get Aust’s biggest solar farm posted 9/5/2012 on 9NEWS).

International solar power company Fotowatio Renewable Ventures (FRV) will construct and operate the 20 megawatt facility, the ACT Government announced on Wednesday…

ACT Environment Minister Simon Corbell said the solar farm would be able to power 4400 more Canberra homes with only a $13 annual increase to all householder power bills.

Canberra, Australia, is located at about 35° south latitude.  Which puts it between the Tropic of Cancer and the Antarctic Circle.  So the sun never gets directly overhead.  The Tropic of Capricorn at about 23° south latitude (above Canberra) being the cutoff point for that.  Which means Canberra gets about 6 hours or less of sunshine during the months of May, June and July.  The month of December sees about 9.4 hours of sunshine each day.  On average their mean daily sunshine is approximately 32.1% each year (about 7.7 hours of sunshine out of the 24-hour day).  According to the same website linked to above their mean number of clear days averages to about 27.5% each year.

When you factored these together (as well as blowing dirt, bird droppings, etc.) you can understand why the capacity factor for solar power is only about 18% of the total possible output over a period of time.  So that 20 megawatt rated solar power plant may only provide about 3.6 megawatts of useful electric power.  Which would be the equivalent of power for maybe 300 homes (with a 100 amp service at 240 volts).

Their claim of powering 4400 homes is questionable.  If you divide that 20 megawatts by 4400 homes and then divide that number by 120 volts you get 37.88 amps.  Which is just over two fully loaded 20-amp circuits.  Or just over three fully loaded 15-amp circuits.  Take a look in your electric panel in your house and see what that will get you.  If you have a typical panel you probably have 20 circuits.  Divided up between 15-amp and 20-amp circuits.  With maybe a 2-pole breaker (240V) for an electric stove or central air conditioning.  So that 37.88 amps at 120 volts isn’t going to power a lot in anyone’s house.

This new power plant will add to the electric grid during those few daylight hours.  But it will be all fossil fuel-powered plants powering these homes once the sun sets.  Unless they add a lot of equipment to store excess power when the sun does shine to use when it doesn’t shine.  But if a typical house uses more than 37.88 amps at 120 volts (or 18.94 amps at 240 volts) there probably will be no excess power to store.  Meaning this new solar power plant will have little impact on the electric grid.  It will just cost the electrical consumer more.  While making little if any impact to the carbon footprint of their fossil fuel-powered plants.

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