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How much power do you get from solar panels?

Solar power is used all over the world for powering everything from road signs and parking meters, to houses, offices, and even factories.

So you can get a lot of power from the sun. For free. Every day. Forever. And, it’s completely clean.

When connected to a battery system, a solar panel array can produce all the power that a household needs. This eliminates the need for a costly electricity distribution grid. The sun delivers power everywhere, no need for wires! In the developing world, solar power is being used to leapfrog into the 21st century.

The exact amount of power you get from a rooftop-style solar power system (called “photovoltaic” in the industry), depends only on the size of your system, and how much sun it gets. In our case, we have a moderate sized, 3,150 watt array, and on average, for the whole year, it generates about 50% of the electricity we use in our house.

These days, as the efficiency of panels improves, you can reach even higher percentages. Our roof is pretty small, so on a larger house, in the right location, with the latest panels, it would be possible to put up a system that would produce all your electricity (or at least, would produce electricity equal to what you consume).

And that’s just on small residential systems. In 2006, a 100 kilowatt array was installed on the roof of the Horse Palace on the CNE grounds, here in Toronto. It was the largest photovoltaic system in Canada at the time.

These days, 100 kilowatts sounds quaint. With the FIT program in Ontario providing large incentives for investing in renewable energy, there are several even larger systems in the works all over the province.

In September 2009, a 9,100 kilowatt array came online near Napanee, Ontario. At 91 times the size of the Horse Palace array, it was the largest solar array in Canada at the time, producing enough power for 1,000 homes.

The glory was short lived. Less than three months later, an even larger facility with 20 megawatts (20,000 kilowatts) came online in Sarnia, Ontario. This system was expanded in 2010, to become the largest in the world, at a grand total of 97 megawatts, enough power for over 12,800 homes. That’s about thirty thousand times larger than the solar array on our roof.

Around the world, you can find many other large, utility grade facilities. Europe has several that are over 40 megawatts, including the previous largest in the world, the 60 megawatt Olmedilla power station in sunny Spain. They’ve built even more since then, including one in the Ukraine even larger than the Sarnia location.

Sunny Australia is also getting in on the action, with plans for a 154 megawatt plant in Victoria by 2013, and a few others on the drawing board.

The Chinese are the current record holders, with a 200 megawatt plant now in operation. Not to be outdone, the Americans currently have plans for several new photovoltaic power stations with capacities ranging up to 675 megawatts. (The US already has the world’s largest solar thermal plant in the California’s Mojave desert, with a capacity of 354 megawatts.)

To put that in perspective, a natural gas turbine power plant, like the ones that have been built in Ontario over the last few years, generates about 500 megawatts. A single nuclear reactor in one of Ontario’s three nuclear power stations has a capacity between about 800 and 900 megawatts. So at 600 megawatts, solar power looks like it’s getting up there to the same generating capacity as other major systems on the grid.

Unfortunately, it’s not quite that simple, but it is very promising. Solar power can clearly be a major contributor to the public power grid.

But the most transformative potential of solar power, is that it can enable a fundamentally different, distributed power system, where we don’t even need a grid at all, at least not for residential use. The sun delivers energy everywhere, for free! We can create power where we need it, in locations where other forms of power generation are completely impractical or impossible. And we don’t have to transport it over huge distances at great cost.

That’s the kind of power supply system that developing countries are going to get by default, because it’s totally impractical and too expensive for them to build a western-style power grid. It’s already happening with the telephone system — cell phones have brought instant communication to distant villages long before copper wires ever would have reached them.