Understanding Solar

Introduction

Basically the Sun releases energy in the form of sunlight and heat. Both these two types of energy can be harnessed. Solar heaters make use of the heat energy from the sun to heat water, gases and other fluids. On the other hand, solar panels convert sunlight into electricity.

Diagram showing solar energy conversion - Kamtex SolarSimple working principle


Solar Panels

Small cells called solar cells are connected together to form a solar panel. Solar panels in turn are connected together
to form large systems called arrays.

A single solar cell. Solar panels are made of solar cells. - Kamtex SolarSHARP solar panel - Kamtex SolarMultiple solar panels combine to form a solar panel array. - Kamtex Solar
A small cell, solar panel and aray (Left to right)

Solar panels work hand in hand with other important components to form a solar electric system. Typical components include a solar charge controller, rechargeable battery and an inverter.

Solar Charge Controllers

Phocos Charge Controller CML 250. Protects your solar panel investment. - Kamtex Solar

The charge controller is an important component prevents damage to the battery and solar panel. It regulates the charging of the battery to prevent overcharging and blocks current backflow from damaging the solar panel.

 

 

 

Rechargeable Batteries

Solar DC Rechargeable Batteries are essential for remote stand-alone off grid systems - Kamtex SolarRechargeable batteries are used to store the electricity produced by the solar panels. This allows electricity produced
in the day to be stored and used at night or as when needed.

 

 

Inverters

DC to AC inverters are needed to run AC-powered appliances - Kamtex SolarInverters are used when normal AC appliances are used in conjunction with the solar electric system. It should be noted that solar panels produce direct current (DC) electricity. Common household and industrial appliances use alternating current (AC). Therefore, an inverter is needed to convert DC to AC before any AC appliances can be used.

Advantages of using an inverter are that most normal AC appliances can be used. The disadvantages are that there will be energy wastage during the less than 100% efficient conversion process and obviously there is the additional cost of purchasing an inverter.

Alternatively, DC appliances are available that do not need inverters at all. Common DC appliances include DC lightings, fans and water pumps.


Different types of solar electric systems

Direct-Connect System

A direct-connect system consists of at least a solar panel and any appliance that can draw DC electricity from the solar panel. As the name applies, the DC appliance is connected directly to the solar panel. In such a case, the appliance will work only when sunlight is available. This means that it will not work at night. Usually loads that run in direct relation to the sunlight intensity works best in this configuration e.g. a solar attic fan where the the fan runs faster as the sun gets stronger to cool the attic space in the daytime. A solar direct water pump for irrigation is also a perfect example.

 

Grid-Connect System

A grid-connect system allows energy produced by a solar electric system to be fed back to the electricity grid. Depending on the regulations in different countries, the excess energy produced by your solar system can be sold back to the electricity gird company, thus helping cut down on the monthly utility bills. When sunlight is available, your solar electric system will be providing you with electricity. When there is no sunlight, the utility grid supplies you with electricity. Thus eliminates the need for batteries to store excess electricity produced by your solar electric system.

Stand Alone System

A stand alone system (often called an off-grid system too) is not connected to any electricity grids. The system is solely responsible for powering any loads connected to it. This type of system is common in remote locations where an electricity grid is not available or too costly to connect to. It consists of at least a solar panel, charge controller, rechargeable batteries and the various loads. The rechargeable battery stores any electricity produced by the solar panels. The charge controller acts as an intelligent central unit where solar panels, batteries and the various DC loads are connected and monitored.

For remote rural areas where there no electricity is available, a simple stand alone lighting system consisting of a solar panel, charge controller, rechargeable battery and some DC lightings will be sufficient. For bigger systems, an inverter can be added to allow AC appliances and loads to be used too.

Diagram showing solar panel connectetd to DC load only - Kamtex SolarDiagram showing AC Loads with inverter connected to the solar system - Kamtex Solar
Left: DC load only. Right: AC Loads with inverter

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