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Solar Panel Efficiency

By Kristy Hoare on in How it works

Solar Panel Efficiency

Efficiency can be associated with all things electrical, however solar panels command their own definition of 'efficiency'. Below you can find helpful explanations as to what is commonly referred to in the industry as "solar panel efficiency".

What is Solar Panel Efficiency?

It is the amount of energy produced in relation to the area of solar cells exposed to useable sunlight.  A percentage is given to this ratio, then we are able to compare different solar panels based on this technical specification.  Solar panel efficiency is often referred to as ‘solar panel conversion efficiency’, or an easier way to think of it is how much sunlight can be converted into power

What is a typical Solar Panel Conversion Efficiency Rate?

The range of solar panels on the market today has an efficiency rate between 14% and 21% conversion efficiency.

Efficiency of Solar Panels Available In New Zealand

Trina Solar’s PD14 – 290W – 16% panel efficiency

Mitsubishi Monocrystalline Premium – 270W – 16.3% panel efficiency

Renesola Virtus II - 260W - Module- 16% panel efficiency

Test Conditions for Measuring Solar Panel Efficiency

STC (standard test conditions) is the industry standard for testing the efficiency of solar panels.  STC specify standard test conditions including the temperature of the solar panel, the solar irradiance and mass of the air.

Most solar panel manufacturers will publish the STC percentage on the specification sheets for their solar panels, which gives us a good indication of how one solar panel performs compared to another product.

Are High Efficiency Solar Panels Better?

Many customers appear to prefer higher efficiency solar panels, but at what cost? Higher efficient panels are more expensive, so it might be worth considering the value of the real estate and where the panels are going to be placed.  If the solar panels are going on a large warehouse roof then the efficiency might not be so important, because you can just add more panels to reach the system size you want.  If the solar panels are going to be on a solar power farm, where the land was specifically developed to house solar panels, then having higher efficiency and a higher output for each solar panel might be more important.

 

Showing 2 comments

Posted by Kristy on 23rd Jul 2015 16:38:56

Hi Pendowr

Most solar panels are fairly standard these days, they don't vary greatly from brand to brand.

There are a few things you can do to check that you are getting the best: Check to see if they are Tier 1 panels, versus Tier 2 or 3. Make sure they have 25 year performance warranty and a 10 year manufacturing warranty. Check that they have an efficiency rating of at least 13%. Also check that the solar panel company has been around for a while or if they are backed by good insurers, so in 24 years time if they panels fail then they can be replaced or compensated for. You could also do a search for the solar panel brand on forums.whirlpool.net.au - There can be a lot to learn from the Australian boom in solar power. There is a lot of feedback on there about different brands.

The solar installation company will be able to provide you with spec sheets for the solar panels.

Posted by Pendowr on 23rd Jul 2015 14:27:56

Hi Kirsty,
We are currently making the final decisions to purchase 16 PV panels for 'stand alone' system in the Marlborough Sounds. There is a significant price differential between panels on offer in NZ. How do we make a realistic assessment between the panels on offer or do we simply go for the lowest price and hope that their efficiency will last?

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