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Which Solar Battery Charger | MPPT Vs PWM

MPPT 3-Stage solar battery charger

MPPT 3-Stage solar battery charger

Three Step Charge Algorithm. The most reliable method to charge your solar batteries

Introduction. The main concept of MPPT Solar Chargers

In order to generate the maximum power from a solar panels, the charge controller has to track the optimum current-voltage point on the current-voltage curve: This is called the Maximum Power Point.  Our MPPT controller does exactly that. The low cost PWM controller connects the solar panels to the battery. This algorithm acts as a switch, when it is closed solar panels and battery will be at the same voltage (plus voltage losses in the cabling and controller). It is obvious that the solar panel will never produce the maximum power as it is written on the label.

PWM Controller

Let’s assume that you try to combine a low cost PWM Solar inverter with a 24V battery bank and 250W Solar panel. During the charging process the 250w panel will be connected directly to the 24V battery. The ouput current of the panel is 8.28A  but with the PWM charging at 24V, this panel will produce only 8.28A X 24V that is 198W (you lost 52Watt).

The performance of the PWM controller is getting worse in cloudy and rainy days when the voltage of the solar panels are even lower. The nominal battery voltage will drop under heavy loads during the discharge process, as a result the 250watt might only be able to produce around 150W.

Even the hottest days with high solar radiation, at very high cell temperatures the voltage drop off point will decrease below the voltage required to charge the battery 100%.

MPPT Charger

It is possible to connect standard inexpensive grid-tied solar panels to any of our solar battery chargers and inverters. If the Vmp of the solar module is greater (let’s assume 36V for a 250w monocrystalline panel) than the battery voltage, then the battery current (Amps) will be adjusted proportionally to be greater than the solar panel input current.  The MPPT algorithm can reach 99% efficiency, that means the input and output power will be perfectly balances. MPPT chargers will run your off-grid solar system at the maximum power point , as a result the wast of energy will be negligible.

How Maximum Power Point Tracking Works

In order to optimize the charging process we have to use the MPPT algorithm.

MPPT performance curves compared with PWM controller

MPPT performance curves compared with PWM controller

The speed of charging

Charging the batteries faster it is not always the right solution. The faster the charging and discharge process the less the energy your battery can store. We prefer to use intelligently fast controllers that will charge the batteries in 3 stages

Our MPPT Solar Battery Chargers

We have three powerful solar battery charges that meet the demands for small medium and high power off grid systems. Whether we are planning to charge a small 12V battery in your motor home, caravan , boat or a large 48V battery bank we have the right technology always with MPPT charger.

Conversol SCC MPTT 3kW. 12v / 24v / 48v

Conversol 3kW Solar Battery Charger. 12V/24V/48V.

Conversol 3kW Solar Battery Charger. 12V/24V/48V.









Auto adjustable 12v/24v/48v solar battery charger with MPPT controller

Auto adjustable 12v/24v/48v solar battery charger with MPPT controller

Conversol MPPT 600W 12V & 24V Solar Battery Charger

The Conversol SCC 600 MPPT. 600W Solar Charger

The Conversol SCC 600 MPPT. 600W Solar Charger

 The premium range Master charger from Mastervolt.

Mastervolt Advanced MPPT Solar Charger 60A, suitable for 12V, 24V and 48V batteries

Mastervolt Advanced MPPT Solar Charger 60A, suitable for 12V, 24V and 48V batteries

Mastervolt 60A charger. Up to 3kW power from solar panels. Monitoring and control via modbus

Mastervolt 60A charger. Up to 3kW power from solar panels. Monitoring and control via modbus

The sun as an additional energy source

Solar photovoltaic cells generate electricity from day light even in cloudy days . This form of renewable energy supports your independence and keeps your solar batteries fully charged all the time The rate of charging and method of charging play a key role in the performance of your battery.

Efficient, reliable and safe

It is very important to choose the best battery charger because high tech chargers from Mastervolt and Voltacon maximise the energy yield. The MPPT controller will track with 99% accuracy the the maximum power point of your solar panels.  The solar regulators are suitable for any solar system with voltages 12V, 24V and 48V and charge all type of batteries such as lead acid, AGM, GEL and lithium.

We use only 3-step  charging method to guarantee an extra-long lifespan for your batteries. The three steps are described below.

Versatile and flexible

Mastervolt solar charge regulators can be used flexibly to complement your energy system, or in places where no electricity is available, such as remote holiday cottages or chalets. In addition, the solar charge regulators are a perfect mobile solution for campers, special vehicles, yachts and traffic & information signs. They are also ideal for professional applications at remote petrol stations, telecom relay stations or offshore units.

During the absorption phase the charge voltage is kept at a relatively high level in order to fully recharge the battery within reasonable time. The third and last phase is the float phase: the voltage is lowered to standby level, sufficient to compensate for self-discharge

Battery charging is accomplished in three automatic stages: BULK, ABSORPTION and FLOAT

  •  BULK: At this stage the charger delivers its maximum current for quick charging from 0 to 80%
  • ABSORPTION: The charger has reached its maximum charge voltage and the charge current will slowly decrease until the battery is charged up to 100%
  • FLOAT: This stage begins once the battery is fully charged. The battery remains in fully charged state.


See Figure 4. When the battery temperature is low, the charge voltage increases. On the other hand, when the battery temperature is high, the charge voltage is decreased. Over charge and gassing are prevented this way. This will extend the life of your batteries.

Find out more about our Solar Battery Chargers by following this link. For our On-Grid inverters, please click here. Don’t forget to read our other Blog posts to learn more about the Solar industry. If you have any questions, feel free to ask us, we are here to help.fa

Stefanos Kandilidis
Stefanos Kandilidis
Electrical & Electronic Engineer at Voltacon Power Conversion. He used to work at the renewables R&D department General Electric for 8 years.

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