Solar Energy for all of us...



  • Off-Grid
  • Net-Metering
  • MPPT vs PWM Charge Controller

OFF-GRID Topology

  • Solar Panels
    The source for clean power
    • Use solar panels for your off-grid system.
    • These newer models are capable of generating more power per panel than 5 or 10 years ago....
    • From a 64.5"x 38.5"x1.57" panel you can get 250W+ today.
  • Charge Controller
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    A charge controller will take the solar panel Volatge and Current and adapt them for battery charging. Depending on the model you can input 2 to 150VDC in to them these days and convert it to 12/24 or 48 Volts for the battery side. They use various techniques to charge batteries, MPPT being the best of them.
  • Batteries
    Don't need much introduction
    • They accumulate charge, you get to use that charge any time night or day.
    • The more you have in your system, the longer you can run your appliances.
    • You have to use a charge controller to charge them, never connect them directly to a Solar panel.
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  • Inverters
    • They convert 12/24/48V DC to 110/220V AC
    • They come in Pure or Mdified Sine Wave.
    • If you want your devices to last longer, use the Pure Sine Wave (PSW) model.
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    TV

First of all, what is Net-Metering...?

With Net-Metering you can:

  • Reduce your Hydro bill
  • Use Hydro as your battery backup, meaning you don't have to purchase any batteries.
  • System is very simple, Solar Panel -> Grid-Tie Inverter -> Electrical Panel in your home

 

Question always comes up, is MPPT better than PWM?

 

Answer: A BIG YES

Here is why...
(assuming perfect conditions)

PWM

When you connect a PWM charge controller to a 250W solar panel charging a 12V battery, the controller puts out the maximum current the panel produces out, 8A in this case, but only takes 12V from the panel to charge the battery.

12V x 8A = 96W is what the controller puts out to charge the battery, while the panel is capable of 250W.

MPPT

In this case the controller looks for the best power point from the 250W panel by sweeping the Voltage and Current lines from 0 to MAX and once it has found it, it starts to convert the MAX power into charging the 12V battery. 250W panel puts 30V and ~8A current out.

250W / 12V = 20A

MPPT controller will put out 12V and 20A of current into charging the battery, it takes 30V and 8A from the panel.

At $180 for a basic TS45A PWM charge controller, your charge current is 8A
At $350 for a Phocos MPPT controller your charge current is 20A

 

This means:

  • You will spend ~3 times less time to charge the battery with an MPPT controller.
  • You are spending less than 2 times on the MPPT controller.

You decide which one is the right controller for you.