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The AC/DC Debate

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The AC/DC Debate

Edison  versus Tesla Lessons in Electrical Efficiency

There are two different forms of electrical current flow in a circuit; Alternating Current (AC) and Direct Current (DC).

Both forms of current flow work, each with their own distinct advantages and disadvantages and are widely used today within various applications…So why has there been so much fuss lately about which one to use again?

Let’s go back in time a bit. AC versus DC …Tesla vs Edison.

The battle of DC (Direct Current) and AC (Alternating Current) isn’t a new battle. The “War of Currents” dates back to the 1880s between Thomas Edison and Nikola Tesla. Edison developed the first electric power system which used DC current. Tesla invented transformers and Alternating Current.

The main reason why AC won the battle back then; Transmission.

Edison could only supply to customers within a mile and a half of the power plant, where AC can be transmitted a further distance and supply to the customers that Edison wasn’t able to provide for. Therefore it was more economical to use AC Power back then.

With the invention of semiconductors in the 1970’s transforming from AC to DC economically became a reality.

Some of the common DC Applications using semi conductors in our lives are:

  • IT Networks and Systems
  • Smart Phones, Tablets, Laptops etc.
  • Lighting (CFL and LEDs)
  • Appliances
  • Electric Cars

Interestingly enough, if you’re reading this on a laptop, you are actually using both kinds of current. The Nozzle Shaped plug that goes into your computer delivers a direct current to the computer’s battery, but it receives that charge from an AC plug that goes into the wall. The awkward little block between the wall plug and your computer is a power adapter that transforms AC to DC.

Now the war has been revisited over the number of years, and while we live in an “AC World” most equipment is still DC powered with an Inverter installed in nearly all products.  Switching from AC to DC results in conversion losses and the efficiencies drop. There are multiple conversions that happen from power generation to the end user which could result in at least 5-10% loss through conversion. In Figure 1, the AC grid clearly shows that going back and forth from one type of current to another becomes costly in terms of efficiency losses.

article-ac-dc

To try and solve transmission dilemmas, new technologies of High Voltage DC (HVDC) have been implemented to compete with AC transmission.

If you have solar panels (Flat Panels or CGE’s SOMs) or Wind Generation they generate DC power, that’s one less conversion that needs to take place, increasing the efficiency of the system.  With the panels or renewable energy generator being either in your yard or on your roof, transmission losses aren’t an issue. If you are running your cottage on solar power, would

n’t you want to use the most out of the energy that’s been produced and not lose it to conversion losses?

If we take a look at Figure 2: Two Solar Systems – A typical flat panel using high volts and low amps versus CGE High Amp Panel; both panels have the same wattage but the flat panel is using an DC/AC inverter and the CGE panel is running strictly DC.  With the conversions and less amperage, you notice the flat panel can only support 25 – 12V/7W light bulbs versus 46 LED bulbs with CGE’s SOM.

article-solar-som

 

Commercial buildings are also possible! There are DC powered buildings already built and with the Net-Zero Energy Buildings after 2020 in the EU, DC does look favorable. In commercial applications avoiding local rectifiers and power factor correction circuits will make building appliances much more efficient. This means the lighting, the HVAC, the IT networks and computers are all DC based, wouldn’t it make sense to get rid of the conversion losses?

What this all means is that straight DC has better efficiency and more power.

Added benefits of using solar DC are:

  • a lower carbon footprint,
  • lower electricity/energy bills
  • less reliance on the grid for your electricity demands and
  • selling excess power back to the grid with net metering.

With the addition of a Nickel Zinc battery within our completely integrated SOM solar system you will also have battery backup for grid blackouts due to natural disasters or grid protection brownouts. (NB: brownouts imposed by utility companies to reduce grid loads in emergency or extreme peak demands).  Our battery can also be utilized as an energy source to offset the cost of electricity during peak demand pricing for additional cost savings.

You still may be asking…Why are we at Crystal Green Energy giving you this lesson in electricity? Well, the lesson we are really interested in is the efficiency lesson. CGE Solar Optic Module Systems convert the Sun’s energy into thermal energy and pure DC power at an extremely high rate of efficiency and provide 27 Amps at 12V.  This is where CGE differentiates itself from any of its competitors. Our goal is to provide the public the knowledge to make an educated decision on renewable energy choices for the cottage, home, office or commercial building.

Harnessing the Sun Today… For a Greener Earth Tomorrow 

Image Sources:

Edison Versus Tesla  – http://www.imanengineer.com/5-famous-engineering-rivals-throughout-history

Figure 1 – http://www.led-professional.com/resources-1/articles/direct-current-dc-supply-grids-for-led-lighting