Hopefully by now our various blog series have helped remove some of the mystery surrounding Solar Panels, but there is one subject we haven’t really talked about in much detail – namely electricity.
You’d think since the solar panels on your home use energy from the sun there would be a bit of work involved to convert all that raw solar energy to usable electricity, but it’s quite simple (though there is a bit of magic).
The War of the Currents
So if we travel way back to the 1800’s, there was a little war you might not be too familiar with called The War of the Currents. While not a shot was fired, its outcome has forever altered the course of history and shaped the world we live in today.
To summarize a very long and interesting historical anecdote, Thomas Edison – the premier inventor – got into a battle of sorts with George Westinghouse over the large-scale adoption of electricity. Edison advocated for direct-current electricity, and Westinghouse (who owned the patents of Serbian inventor Nikola Tesla) supported alternating-current.
Long story short – Edison launched a smear campaign against the use of alternating-current and even went so far as to electrocute animals (including an elephant) to illustrate the ‘dangers’ of AC power. Unfortunately for him and his commercial enterprises, DC power lost the war as AC was much cheaper to expand on a large scale.
What’s the Difference Between AC and DC?
Direct-current (DC) is exactly as it sounds – it’s current that flows directly along one path. Electricity itself is the flow of electrons. If we make a comparison between DC and cars driving around a racetrack, the cars are like electrons – they move in one direction around a circuit like cars would circle a racetrack.
Alternating current is – as you guessed it – current that alternates directions. Here in the U.S., we use AC that alternates 60 times a second, or you could say it runs at 60 hertz. This is the frequency of electricity, and it should be noted that this number changes around the world.
Without getting too buried in the circuits, AC has the tremendous benefit of being easily transported great distances fairly cheaply. Your home probably isn’t located next to a giant solar farm or a nuclear plant, so often the electricity you use comes from great distances via transmission lines.
For DC power to work effectively, whatever it is you wish to power needs to be in relatively close proximity to the electricity source and often it will require thicker wires and more expensive facilities to transport.
Do the Solar Panels for My Home Produce AC or DC electricity?
When sunlight hits a solar power system’s surface, it excites the electrons in the semiconductor (the silicon in the solar cell). When the electrons are excited they want to move, but because of the way cells are manufactured, the electrons can only really move in one direction in a closed loop.
From our racetrack example above, we know this to be indicative of DC, and that is exactly what is produced by the solar panels for your home. Since the U.S. uses AC on a large scale, solar power systems need a way of switching between AC and DC or inverting the electrons during their flow. This is where inverters and micro-inverters come in.
An inverter takes the DC electricity produced by your residential solar panels and converts it to useable AC for your home’s devices and transportation through the electrical grid.
Now was Edisons work all for not? Certainly not. DC is actually used a lot with portable electronics like your phone, laptop, and cars – pretty much anything with a battery.
Fun fact – that little box on your laptop’s power cord is doing the same thing as a solar micro-inverter. It’s changing the AC power coming out of your home’s outlets to DC for storage in the device’s battery.