The PWM method is used in cheaper systems and with it, voltage that is seen as surplus electric power goes to waste. MPPT differs from PWM, in that surplus voltage is converted to electric current for charging. As a result, charging efficiency increases by around 20% with MPPT.

1. Charging is possible in adverse conditions, such as when it is raining or cloudy, as is the installation of equipment in locations where daylight hours are short.

2. It is possible to realize more compact panels and batteries, thereby suiting the need for smaller, more lightweight equipment.

3. Customers can realize lower costs with our unique designs for MPPT, which until now has been expensive.

The three devices necessary for solar charging are a solar panel for converting the sun's energy into electricity, a battery for storing the electric power generated by the solar panel, and a charge controller for safely and efficiently charging that battery from the solar panel.
Furthermore, in order to safely use the electric power that is stored in the battery, it is necessary to have a charge and discharge controller to monitor the condition of the battery, and an inverter to convert the electricity that is necessary for the device being used.
Particularly with lithium-ion batteries, if their condition is not managed, not only will this lead to their considerable deterioration, it can also lead to serious accidents, such as the batteries emitting smoke or catching fire. As such, charge and discharge controllers play an important role.

How solar panels generate electricity

When light is shined on two types of silicon semiconductors superimposed on each other, the electrons in the semiconductors begin to move. When a battery or light bulb is connected to these semiconductors, electricity flows.

Types of solar panels in practice

Types of solar panels in practice

Silicon-based

Silicon solar panels are currently the most widely used type of solar panel.

Monocrystalline silicon type

Silicon crystals are arranged in regular rows, so although conversion efficiency is high, it is expensive.

Polycrystalline silicon type

This type is made by melting and solidifying fragments of silicon crystals produced during the manufacture of monocrystalline silicon. Although the conversion efficiency is lower than that of monocrystalline silicon, the price is lower because it is easier to mass-produce and manufacturing costs can be reduced. It is currently the most widely used type of silicon.

Amorphous silicon type

Unlike monocrystalline and polycrystalline silicon, this panel uses amorphous silicon, which has an irregular crystal structure. It is less expensive than crystalline silicon. It is also lightweight, easy to process, and the voltage can be adjusted freely, but its conversion efficiency is only about half that of crystalline silicon.

Other-coupling type

This is a structure in which different solar cells are stacked on top of each other.
It has better conversion efficiency than the monocrystalline silicon type, but the manufacturing cost is higher.

Compound type

CIS/CIGS type

The CIS type consists of copper, indium, and selenium as the three main materials. The CIGS type also uses gallium. Although they have a lower manufacturing cost than the silicon type, their conversion efficiency is lower than that of the silicon type.

GaAs type

GaAs type is made of gallium and arsenic, and its conversion efficiency is higher than that of monocrystalline silicon type, but it is currently used for only a few applications such as satellite applications due to its high cost.

About battery, rechargeable battery, or storage battery

Battery, rechargeable battery, or storage battery Refers to rechargeable batteries that can be repeatedly charged and discharged. There are various types of batteries, ranging from small ones for electronic devices and mobile devices to large ones such as emergency power sources for facilities, etc., that make people's lives more convenient or protect human lives, depending on their applications and capacities.

Main battery types and features

Main battery types and features Refers to rechargeable batteries that can be repeatedly charged and discharged. There are various types of batteries, ranging from small ones for electronic devices and mobile devices to large ones such as emergency power sources for facilities, that make people's lives more convenient or protect human lives, depending on their applications and capacities.

	cell voltage	operating temperature limits	cycle life	danger	features
Pb	2	0～40℃	3150		safty / heavy
LiCoO2	3.6～3.7	-20～60℃	500～1000	fuming or ignition
LiMn2O4	3.7～3.8	-20～50℃	300～700	fuming
LiFePO4	3.2～3.3	-20～60℃	1000～2000	fuming
Li（Ni-Mn-Co）O2	3.6～3.7	-20～60℃	1000～2000	fuming or ignition
LiNiO2	3.6	-20～60℃	500
LiMn2O4	2.4	-20～60℃	3000～7000	Does not ignite

※There are differences in the nominal value depending on the manufacturer

Electric power generated by solar panels varies depending on changes in daylight conditions, such as where the solar panels are installed and in what climate. But when a battery is charged with voltage that is unchanged and the maximum voltage that it can accept is exceeded, this can cause the battery to be damaged. And if the voltage is too low, electric power that has been accumulated can be lost due to electric current flowing from the battery to the solar panel side.
That is when a charge and discharge controller is needed. Charge and discharge controllers have two charging methods, each with its merits and demerits, so they should be selected to fit their purpose.

PWM (pulse width modulation) method

Control with this method produces a fixed voltage and electric current.
The merits of this are that it can be introduced at a comparatively low price and enables charging at a constant efficiency, without the battery or load being affected.
A demerit is that charging is not possible at the greatest efficiency because it cannot be operated to suit daylight conditions, which are changing all the time.

MPPT (maximum power point tracking) method

Even in daylight conditions that are constantly changing, MPPT enables continuous control and is constantly monitoring to obtain the greatest possible electric power from the solar panels. Compared with PWM, one of its advantages is that it enables highly efficient charging.
Because of this high charging efficiency, users can expect to extend the operational period to when there is no direct sunlight, and the miniaturization of solar panels and batteries. A drawback is the higher cost of MPPT.
Our WSC series uses the MPPT method in a price range that is closer to PWM.