The difference between solar (PV) systems explained

• Panels
• Inverter

PANELS

The primary difference between solar panels is cell materials. The major types of cell material are crystalline silicon and thin films which vary from each other in terms of light absorption efficiency, energy conversion efficiency, manufacturing technology and cost of production.

Crystalline Materials

The crystalline material can be grown as a single crystal (mono crystalline) and cast into an ingot of multiple crystals (poly crystalline).

 Mono Crystalline

Single crystal silicon cells are the most common in the market.  High purity polycrystalline is melted in a quartz crucible. A single crystal silicon seed is introduced into the molten silicon and is drawn slowly out from the molten silicon. Once the single crystal ingot is formed it is sliced into wafers about 200 – 400 micrometers thick. The thin wafers are then polished, doped, coated, interconnected and assembled into modules. 

Compared to non-crystalline materials, single crystal silicon has higher energy conversion efficiency due to its high uniformity in structure. The higher a PV cell’s conversion efficiency, the more electricity it generates for a given area of exposure to the sunlight. This means that fewer panels are required to produce a given amount of energy.

 Poly Crystalline

Polycrystalline silicon is a block of material, which instead of being a single crystal, is made by casting an ingot of silicon, resulting in many small crystals pieced together. Consisting of small grain of single crystal silicon, polycrystalline cell are less energy efficient than single crystalline silicon cell. The grain boundaries in polycrystalline silicon hinder the flow of electrons and reduce the power output of the cell.

Compared to single crystalline silicon, polycrystalline silicon material is stronger and can be cut into one third the thickness of single crystal material. It also has slightly lower wafer cost. However, their lower manufacturing cost is offset by the lower cell efficiency.

The brief comparison of these panels’ features is as follow:

INVERTER

The fundamental purpose of a photovoltaic system inverter is to change direct current electricity from PV panels to alternating current electricity, and finally to power alternating current loads. In grid connected system, inverter is designed to feed into the utility grid and produce output with little harmonic distortion, enabling it to operate even the most sensitive electronic equipment. Standard inverter convert efficiency is normally from 95% to 97.5% of direct current input into alternating current output.  Besides, its feature includes low standby losses, little harmonic distortion, ease of servicing and good reliability. All inverters provided by NUE are complied with AS4777 and listed in CEC approved product list.