Your Guide To Buying a Charge Controller

The world is searching for sources of renewable energy—and solar energy is a big favorite. It reduces pollution, doesn't have the fossil fuel emissions that contribute to global warming, and lowers fossil fuel prices. If you want to reduce your electricity bill, or if you’re using a recreational vehicle and you need a source of energy, you might want to run off solar power and also use a RENOGY MPPT CHARGE CONTROLLER. Photovoltaic (PV) cells convert solar energy into electricity—and this electricity is stored in batteries. There are solar charging battery systems. But once the batteries are fully charged, they can be damaged if they continue to charge. Also, if there is an intensely bright sun, the batteries might not be able to handle the incoming voltage. Charge controllers, also known as solar regulators, are designed to protect the batteries to prevent overcharging. A controller will regulate the current going to the batteries, according to how much they have charged up.  Once a battery is fully charged, they prevent the battery from becoming damaged as a result of being charged any more. But there are a couple of varieties of charge controllers. There are two main types of charge controllers: pulse width modulated controllers, and maximum power point tracker controllers. Each one has a different emphasis: The MPPT controller converts the voltage from the solar panels, to achieve the optimal voltage and power transfer for the batteries. The PWM controller is geared more to protect the life of the batteries, and to make sure that the charge stored in them doesn't leak out so fast.
To help you make the right choice, we have put together this buying guide including everything you need to know about charge controllers to make a good investment. It'll help you:
• Choose the right type of charge controller,
• See useful tips about that type of charge controller,    
• Read reviews of different brands of charge controllers, and what customers are saying,
• Select the right brand of charge controller, and
• Compare prices and find the best deals.

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Types Of Charge Controllers

Charge controllers are voltage and current regulators that are designed to keep batteries from overcharging. Typical solar panels will produce between 16-20 Volts, which could damage batteries that need only 14 volts to charge up.
The first charge controllers would allow charging up a battery until a certain voltage was reached. Then it would turn off. When the battery's voltage would drop below a certain level, it would turn back on and start charging up again.
But then it was realized that the batteries last longer if there are three stages:
1) Bulk: The batteries charge up gradually to the bulk level voltage of 14.4-14.6 Volts, while the batteries are drawing maximum current.
2) Absorption: The batteries' voltage is maintained at 14.4-14.6 Volts for a specified time, and the current decreases, while the batteries charge up to the full state of charge (SOC).
3) Float: When the batteries are fully charged, at the end of the specified absorption time, the voltage is lowered to a “float” level (13.4-13.7 Volts), and the batteries draw a minimum of current, to kept it at that “float” level, until the beginning of the next cycle.
There are two types of charge controllers:
1. PWM—Pulse Width Modulated Controller: These use high-frequency electrical pulses to charge up batteries, and change the current by changing the length of the pulses. They work like a rapid "on-off" switch. They send a series of short charging pulses to the battery and then receive feedback from the battery to see how fast to send pulses, and how wide the pulses of charge should be. When the battery is fully charged and has no load (i.e., there is nothing that drains the charge from the battery), the PWM will only tick every few seconds, sending short pulses. If the battery is totally discharged, the pulses will be long, or the controller will be on constantly to recharge the battery. In between every two pulses, the controller checks the charge on the battery and adjusts accordingly as to how much charge to send. The deficiency of PWM is that it will cause noise interference in radios and TVs, by creating sharp pulses. These are used for 12 V batteries that give 30 Amperes of current, but you can find models suitable for up to 60 Amperes of current. A streamlined version is the Morningstar SunGuard SG-4 Charge Controller. It is a single-module, PWM controller, which has two connections to the solar panels, and two connections to the solar batteries. The controller monitors the battery charging and makes sure that the charge on the batteries doesn’t leak out at night, or when there is very little sunlight. 
2. MPPT -Maximum Power Point Tracker—This involves a computer-driven circuit that scans the battery voltage and the photovoltaic array voltages at regular intervals. This allows calculating the match between the photovoltaic voltage and the battery voltage. This ensures that the power from the batteries is a maximum. (The electronics definition of power is Power = Volts x Current.) Since this controller is more complex, the MPPT controller is also more expensive. It is also suited for greater currents than the PWM controller—up to 80 Amperes. The SolarEpic 4215BN MPPT 40-Amp Solar Charge Controller is an example of a maximum power point tracker controller, which has the benefits of protecting against over-charging and over-current, as well as temperature extremes. The Tracer MPPT Tracer 3215RN Solar Charge Controller is designed to monitor the changes in the voltage of the solar panels during the different times of day and different temperatures.

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What People Are Saying

Based on all the consumers' reviews we've scanned, these are the top things they mentioned about their new stuff:
• Protection features: Make sure that the charge controller provides protection vs. overcharging, overload, short circuits, power surges, and undercharging: There also is “load control mode”, or “low voltage disconnect”, where the controller disconnects the appliances from the system when the battery voltage gets too low. Otherwise, that can also damage the batteries.