Common Solar Terminology Explained


Photovoltaic (PV) 

This is the energy from the sun that is absorbed by the solar electricity panels to create DC electricity.  Solar Power is commonly known in the industry as Solar PV which is short for Solar Photvoltaic.


Direct Current (DC)

Is the type of electricity generated by the Solar PV panels from the sun.  Batteries also store DC energy and a lot of older off grid homes still use DC current.  The Solar inverter in a grid tied system converts the DC current to an AC current which households run off.


Alternating Current (AC)

Is the type of current that all grid tied houses and all our appliances run off.



The inverter is the machine or device that converts/inverts the DC energy from the panels into an ac energy so that it can feed the solar power into the house for consumption.  There are 3 main types of inverters, String Inverter, Micro inverters & DC optimisers which we will explain in more depth.


Monocrystalline  or Single Crystal Silicone 

Mono is one of the 3 types of panels.  This is where the crystal lattice silicone is prepared in a single continuous process.  They can be easily identified by their black colour and the white backing sheet.  Mono panels traditionally have had higher cell efficiencies then multi panels, but also a higher temperature coefficient that makes them lose more power as the temperature rises.  These days efficiencies between the 2 types are barely noticeable. 


Multicrystalline or Polycrystalline 

Another type of panel, which is the most popular panel these days and make up the majority of solar panels manufactured today.  They are made by basically combining a lot of smaller crystallites to form a complete silicone cell.  They are easily distinguishable by their blue hue and flecked look to the panel that appears like shards of silicone. Multi crystalline panels perform better in low light and hot conditions compared to mono crystalline panels. Efficiencies between the 2 major types are marginal with none to minimal differences.


Thin Film or Amorphous

A second generation solar cell that is made by depositing one or more thin layers, or thin film (TF) of photovoltaic material on a substrate, such as glass, plastic or metal.  Traditionallly they have been a smaller sized panel compared to mono’s or multi’s and can quite often be flexible.  Thin film panels also a perform under a wider spectrum of light compared to others and can even absorb small amount of UV & Infrared light. They can have between 10 – 30% loss in the first 6 months of their life however due to changes in the photoconductivity and dark conductivity caused by prolonged exposure to sunlight.  They are easily recognisable compared to a mono or multi panel due to their darker colour and smaller physical size. 


Grid Tied

Connected to the national electricity grid. 


Off Grid

No mains or national electricity network connection to site.  The customers house is generally powered directly by solar /wind or generator and stores energy in batteries for use at night.


Net Meter

The meter that replaces the existing electricity meter in the main meterboard.  All net meters are digital meters that record energy consumption from the grid and also keep record of Solar energy exported to the grid.


Smart Meter

A newer type of meter that transmit a customers energy consumption through the electricity grid for calculating electricity costs, other versions also transmit data through a mobile network back to the energy provider.


Energy Meters, Modbus Meters and Inverter Smart Meters 

Brand specific meters that connect to the solar inverter and the electrical mains.  They measure solar production, household energy consumption and solar export for display on monitoring portals or apps.


Solar Hot Water

A form of solar specific for heating of potable and non-potable water supplies.  The suns heat energy is absorbed by absorber plates or Solar Collectors /evacuated tubes which heats the water inside a storage tank.



The principal that most roof mounted solar hot water heaters work off.  When the sun warms the fluid inside a absorber plate commonly known as a solar collector it will rise and move into the storage tank.  Thermosiphons must be installed with a minimum roof pitch for them to operate correctly and the tank must be higher than the collectors to allow the heated fluid to rise into the tank.  Solahart pioneered the solar hot water industry in the early 1950’s using solar collectors and utilised the thermosiphon principal.  A thermosiphon system requires no pumps or sensors for the fluid to move around the system making for a much simpler less problematic operation with no moving parts.  The new Solahart collectors and hot water units are equal to or more efficient then a large number of evacuated tube manufacturers including Endless Solar, Hills Solar, Therman & Apricus. 

Collectors or Flat Panels

Collectors or flat panels are a flat panel with a glass face with a collector tray inside which has risers or little tubes in them for the fluid to rise up.  Flat panel collectors are the most common type of solar hot water panel found in the market.  Solahart collectors use a safety glass on the face so are much safer if they were to be broken compared to evacuated tubes.  Flat panels collectors are much tougher against impacts like hail and can survive much larger and intense hail storms.  Much to contrary belief Flat panel collectors can achieve the same and more efficiency than an evacuated tube system. 


Evacuated Tubes

Evacuated tubes are becoming a popular option in solar hot water.  They were originally developed by Solahart Industries and the University of Technology Sydney back in the late 1980’s early 1990’s.  Solahart found no need to pursue the technology as tubes weren’t as suitable to the extreme weather we experience in Australia and the technology moved overseas soon after. The evacuated tube systems work similarly to a thermosiphon system where fluid inside the copper probe is heated in the tube.  The copper probe sits inside a manifold along with the other probes, cold water then passes along the probe which transfers its heat into the cold water making it hot.  A pump is required to move the water from the tank to the manifold and back down again.  Evacuated tubes rely on pumps and sensors for normal operation of the system with more moving parts and components required for operation they can be more problematic compared to a thermosiphon system.