Efficiency of solar panels and what impacts performance

February 14, 2024

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Understanding the efficiency and performance of solar panels is key to knowing if they’re a good investment for you. Here’s what you need to know in 5 minutes or less!

How efficient are solar panels and how will that change over time?

Different solar panels will have different efficiencies, but the technology is in a fairly mature place and we're seeing panels consistently producing good amounts of power for 25+ years. Over this time and beyond, the performance will deteriorate and this will vary depending on the panels that you get. Some solar panels have a performance guarantee, such as “95% for the first 5 years and 80% for the first 20 years”. What this means is that in the first 5 years of the life of the panel, it will perform better than 95% of its maximum capacity, and within the first 20 years, it will perform at above 80% of its peak.

Check with your Green Homes Guru about different panels’ performance over time and look for charts like the one below to quickly get an understanding of how they will perform. Don’t yet have a Guru to ask? Book a free call by going through the MakeMyHouseGreen platform here.

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What this means is that for the example guarantee described above, at year 20 in the life of a 330W panel, it will actually have a peak performance of 264W (80% of 330W). So, if you have a system with 12 of these panels (12x330W = 4.0kW) it will still be producing power like a 3.2kW system (80% of 4.0kW) after 20 years.

There are panels with higher performance guarantees, up to around 90% at 25 years, but these are more expensive. For comparison, this higher quality panel will be producing power at ~93% of its original capacity at the equivalent 20-year mark. That is, the 4.0kW system will now be producing power like a 3.6kW system. You will need to consider whether this additional performance, and associated cost, is something that you are interested in.

What impacts the efficiency of solar panels?

The efficiency of your solar panels is dependent on whether they’re mono-crystalline or poly-crystalline panels, but more importantly, on the direction they’re facing, where you are geographically in the country, and what the weather is like, etc… How to get the most out of your solar system is to consider all of these factors, they all come into it!

For example, imagine you had a house that had 10 panels facing due south, and 10 panels facing due north. The panels facing south could be generating 4025kWh per year, while the ones facing north could be generating only 1664kWh per year, the difference being the direction they’re facing. If you were to imaginatively move the house to another part of the country, these numbers would change despite the directions staying the same!

Shading from neighbouring properties, chimneys, and trees, to name a few things, could have an impact on the solar panels’ efficiency as well.

What Are the Key Factors That Affect the Efficiency of Solar Panels?

Orientation and Tilt:

The angle and direction of your solar panels are vital factors affecting their performance. For increased efficiency, panels should face directly towards the sun - southward in the northern hemisphere and northward in the southern hemisphere. Adjusting the tilt angle to match your location's latitude maximises sunlight exposure, leading to more solar power being captured.

Shade:

Shading can be an efficiency killer for solar panels. Even minimal shading caused by nearby structures or trees can drastically reduce panel efficiency. Selecting an installation site with minimal shading throughout the day is essential for maintaining peak performance.

Temperature:

You may be surprised to learn that high temperatures can actually hinder solar panel efficiency. Solar cells operate more efficiently at lower temperatures, so proper ventilation and cooling mechanisms are vital. Adequate cooling can enhance both panel efficiency and lifespan, ensuring optimal performance over time.

Cleanliness:

Dust and dirt accumulation on solar panels can obstruct sunlight and decrease efficiency. Regular cleaning and maintenance are crucial to keep panels operating at their best. Simple cleaning methods like rinsing with water or using specialised solutions can help maintain peak efficiency. You don’t want to miss out on both energy and savings due to some dirt!

Panel Quality and Age:

The quality and age of your solar panels impact their efficiency and longevity. Investing in high-quality panels ensures better conversion efficiency and a longer lifespan, ultimately leading to higher energy production and a better return on investment. And who doesn’t want that?

Solar Cell Type:

The type of solar cells used in your panels influences their efficiency. Monocrystalline cells typically offer higher efficiency compared to polycrystalline or thin-film cells. Understanding the differences can help you choose the right option for your specific needs. Use our guide to help you decide what the right type of solar panels are for your home.

How Is Solar Panel Efficiency Measured?

Solar panel efficiency serves as a measurement of how efficiently a solar cell harnesses sunlight and converts it into electricity. Often presented as a percentage, this metric signifies the proportion of sunlight successfully transformed into usable electrical power. Simply put, higher efficiency translates to increased electricity generation from a given amount of sunlight.

Why Are High Efficiency Solar Panels Important?

A solar panel with a higher efficiency rating, such as 23%, can harness a greater percentage of the sunlight it receives, translating into more power for your home.

While high-efficiency solar panels may come with a higher upfront cost, they offer numerous advantages. Opting for the highest efficiency panels within your budget is advisable. Not only do these panels generate more electricity per square foot of space, but they also often have a longer lifespan. Despite the initial investment, the long-term benefits of higher efficiency panels outweigh the upfront expense.

Additionally, high-efficiency panels are particularly beneficial for installations with limited space. Their ability to produce more power in a smaller footprint makes them ideal for residential rooftops or even commercial properties where space is a premium. By maximising energy output and space utilisation, high-efficiency panels offer a compelling solution for achieving greater energy independence and cost savings over time.

Benefits of High Efficiency Solar Panels:

Solar panels offer an array of benefits, positioning them as one of the most promising sources of renewable energy. Harnessing the power of natural sunlight, they provide an efficient means of generating electricity. What's more, once you've installed a solar panel PV (Photovoltaic) system, you'll enjoy the perks without incurring ongoing expenses.

Here's a glimpse into the advantages these solar-powered systems bring:

Renewable Energy Source: Solar panels serve as a prime example of renewable energy sources, utilising sunlight to generate electricity sustainably.
Energy Independence: By generating your own electricity, you reduce reliance on traditional utility providers, offering greater energy independence.
Lower Electricity Bills: With solar panels offsetting your energy consumption, you can significantly reduce your monthly electricity bills.
Reduced Carbon Footprint: Solar energy production produces zero greenhouse gas emissions, contributing to a cleaner environment and reducing your carbon footprint.
Low Maintenance: Solar panels require minimal maintenance, with occasional cleaning being the primary upkeep task.
Grid Security: Solar panels enhance grid security by decentralising energy production, and reducing vulnerability to power outages and disruptions.
Contribution to Sustainable Development: Embracing solar energy contributes to global efforts towards sustainable development and combating climate change.

Now that you're an expert in the efficiency of solar panels, you should be in a much better position to choose the right solar panel for your needs. We cover more about other system aspects in other articles, but if you have any questions in the meantime, check out our Guru FAQS or drop us an email via team@makemyhousegreen.com.

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