Get The Best Out Of Your Battery With A Top-Quality Charge Controller

Blue Sky Charge Controller

The charge controller works as a voltage regulator. The primary function of a controller is to prevent the battery from being overcharged by the solar panel array. Some photovoltaic controllers also protect a battery from being overly discharged by the DC load.

A PV controller constantly monitors the battery voltage. When the batteries are fully charged, the controller will stop or decrease the amount of current flowing from the photovoltaic array into the battery. When the batteries are being discharged to a low level, many controllers will shut off the current flowing from the battery to the DC load(s).

I Need You

We know you'll be saying that about a photovoltaic controller if you have a battery as part of your solar energy system. But, then, the question is, "Which one?". Or, even, "Which one?" and "How many?".

That's because controllers come in many sizes, typically from just a few amps to as much as 80 amps. If high currents are required, two or more PV controllers can be used. When using more than one controller, it is necessary to divide the array into sub-arrays. Each sub array will be wired into its own controller and then they will all be wired into the same battery bank.

Size And Type

Here we'll give an overview of the sizes and types of controllers available. PV controller capacities range from 4 amps to 80 amps and multiple controllers can be used in parallel for larger systems.

The simplest charge controllers turn off the charge when the battery reaches a voltage near full charge, and turn it on when the voltage drops about one volt.


Pulse width modulated (PWM) controllers turn on and off very rapidly, holding the batteries at full charge, making better use of available power. This is the more traditional type of controller that has been around longest, and they are usually cheaper than MPPT (Maximum power point tracking) (see below) controllers, and, if your solar energy system is a lower voltage sytem, then this type of controller will probably be fine for your needs.

At higher voltages, they are less efficient than MPPT controllers due to the fact that they force your solar panels to operate at the same voltage as your battery bank during charging, i.e. PWM charge controllers reduce the efficiency of one part of your system in order to make it work with another.


Maximum power point tracking (MPPT) charge controllers take power from the charging source at a voltage where it can put out the most power (its maximum power point) and convert that to the correct voltage to charge the battery.

This technique significantly increases the power from a solar array, especially when batteries are discharged, battery voltage is low, and the temperature is low causing the maximum power point voltage of the solar modules to be high.

Most MPPT charge controllers can take an array voltage much higher than what is required by the batteries, allowing the use of modules with higher peak power voltage, designed for grid-tie use.

A higher voltage solar array also allows smaller wire to be used between the array and the PV controller, which can save wire and installation cost in large systems.

Several MPPT charge controllers can accept high input voltages (up to 120+V DC) from your solar array and efficiently reduce the DC voltage to that of your system (e.g. 12, 24, 48VDC, etc) which means you aren't losing any generated power and you are able to use what you generate more efficiently.

Maximum power point tracking allows a PV array to deliver up to 30% more power to a battery than it would if it were connected directly to the battery.

What's Available?

Glad you asked! We carry controllers from several of the top manufacturers, so let's meet them.

  • Blue Sky Energy
    Based in Vista, California, Blue Sky Energy, Inc. began as RV Power Products in 1993. What began as the development of superior AC charging systems for the recreational vehicle market, led them to become an innovative leader in the renewable energy industry with Maximum Power Point Tracking (MPPT) solar charge controllers. In 1998, they changed the direction of the company to focus on the production of reliable, quality driven products for the solar industry.

    We carry the following model(s):

  • Morningstar
    Morningstar is based near Philadelphia, Pennsylvania, and is one of the world's leading suppliers of photovoltaic (PV) controllers and inverters using advanced technology. Their products have been recognized in the international PV markets as some of the most advanced and highest-quality products available.

    We carry the following model(s):

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