Solar capacity tells lies – How to compare solar panels

How to compare solar panels

We’re all taught to believe that, for the most part, bigger is better – and you’d be forgiven for thinking the same when it comes to solar capacity. A larger capacity should mean more power, more efficiency, better return… right?

Unfortunately, it’s not quite that simple. Not to worry though, we’ve broken down just why that’s the case and what homeowners should really look for when choosing a new solar power system.

So, read on to find out how to decide which solar panel system to choose…

 

Solar panel capacity isn’t everything

In a perfect world, solar capacity would be a solid indicator of a panel’s performance. However, this perfect world would need to be in ‘standard test conditions’ at all times, as these are the only conditions in which the solar capacity is actually in full effect.

These conditions are 25°C and solar irradiance (power density received from the sun) of 1,000Wh per sq. meter.

Now, depending on where you live, relying on perfect weather conditions is not a consistent way to operate – particularly if you’re in the UK! Whilst you may experience some great results during the summertime, when autumn, winter, and even spring roll around, solar irradiance will be much lower and your system will suffer.

Furthermore, a panel with a larger solar capacity could quite literally just be larger! A bigger solar panel allows more space for cells, meaning it could be chock full of lower quality cells but still on paper have a larger capacity.

Take this as an example; if a small panel had a capacity of 390W and a 20% larger panel had a capacity of 400W, if you scaled the small panel up to be the same size as its counterpart, it would boast a capacity of 468W.

Over the course of 25 years, that’s potentially thousands of pounds worth of electricity being missed.

In a nutshell, follow the old mantra of quality over quantity – bigger isn’t always better!

 

So, what should I look for when choosing a new solar panel system?

There are three main features to look for, each one providing its own benefits and peace of mind when investing in a new system.

 

Solar Panel Module Efficiency

First off is the Solar Panel Module Efficiency. This is essentially a rating for the percentage of sunlight your panel is able to convert into usable electricity, which is really what it’s all about.

Having smaller panels is not an issue if the ones you do have are much more efficient and you can fit more of them on your roof.

 

Low Light Performance

The most important aspect for the UK. As we mentioned earlier on, having a high solar capacity is great if you experience consistently warm temperatures and high levels of solar irradiance on a daily basis, but for most people that is just not attainable.

For year-round performance, choosing a solar panel system with excellent low light performance will allow you to reap the rewards of solar energy on even the most overcast of days.

Many manufacturers do not include low light performance specifications on their product data sheets, so you might have to do some digging to find out the information you need.

Top tip: Q Cells, Perlight & Jinko are very good.

 

Product & Performance Warranty

Now, this one might sound a bit obvious, but ensuring you purchase from a manufacturer which provides extensive product & performance warranty guarantees your system will stand the test of time.

As time passes and inclement weather takes its toll on your panels, the technical performance of your system can degrade and result in lower efficiency. Not all panels are created equal – look for a 20+ year product warranty and a 25+ year performance warranty guaranteeing generation greater than 82% of year 1 generation. The higher the better.

Having a bulletproof warranty means any drop in your system’s performance can be rectified with maintenance or replacement.

 

So, that should about cover it! To recap, solar capacity should be near the bottom of the list when comparing solar panel systems, instead focus on efficiency, low light performance, and the product & performance warranty.

With that being said, you’re now ready to make an informed choice about which solar panel system is best for you. Good luck! 

faq’s about solar panel systems

One for the zoom family quiz!

In 1921, Albert Einstein won his first and only Nobel prize for his work on describing the photoelectric effect.

In a nutshell, light (a beam of particles) knocks off electrons from the solar cell; the solar cells direct these electrons along a current – creating electricity. In theory, solar panels could last forever as there are no moving parts.

 

Find out more

Solar power panel efficiency has increased significantly over the last ten years so you might be surprised at how much electricity even a small roof could generate.

The smallest system we would recommend would be 9 x 380W panels, covering an area of 17 square meters. (4m x 4.25m).

 

How many solar panels do I need?

No. It’s a common myth. Whilst south facing is the most optimum facing position, as a rule of thumb – an identical East or West facing roof would generate 85% as much energy as the south-facing roof.

You may prefer to have an east and west facing roof than the south and north-facing roof as you could fit twice as many electric residential solar panels on the east/west roof than just south facing.

Even a North facing roof will generate approx 55% as much energy as a south-facing roof. For example, a 20 year old 10% efficient south-facing solar panel would generate approximately the same amount of energy as a modern north-facing solar panel.

 

How do solar panels generate electricity

The installation of solar panels on residential buildings are considered permitted development so you do not require planning permission if they comply with the following conditions.

There are necessary limits and conditions which must be complied with to benefit from permitted development rights.

  • Solar panels should not be installed above the highest part of the roof and should not project more than 200mm from the roof slope or wall surface.
  • Installers should not install solar panels on a building that is within the grounds of a listed building or on a site designated as a scheduled monument.
  • If your property is in a conservation area, or a World Heritage Site, you must not install solar panels on a wall that faces a highway.

Feel free to reach out to us to buy solar panels in the UK & switch to a sustainable lifestyle. Give us a call at 01273 286 627 and request for a free design and quote.

 

Planning Portal

The district network operator (DNO) is the company responsible for distributing electricity from the national grid to your home. Installers must inform the DNO of your installation within 28 days after the date of installation. Leoht will handle this for you.

You do not require permission for systems under 16 amps per phase (3.68kW single-phase or 11.04kW three-phase supply). All of the residential solar panel systems that we install fall into this category. System sizes are based on the AC inverter rating rather than the peak DC output of the solar system.

“By following bad advice regarding output limits you could be costing yourself £000’s.”

 

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Not on their own. But it is possible when combined with a time of use tariff and energy storage – depending on the time of use tariff and smart export guarantee rates.

For example, Octopus Go tariff pays 5.5p/kWh for every unit exported and charges 5p/kWh for off-peak use from 00:30 – 04:30. You could install solar panels that generate the equivalent of 100%+ of your electricity consumption and earn 5.5p/kWh for every unit exported to pay for topping up the batteries in the winter at 5p/kWh.

Your bills could even go negative if you can generate more than you use!

Time of use tariffs are why we have smart meters so expect them to become more common in future.

Yes. Solar panels are worth the cost. We believe that solar pv panels systems are an excellent investment for both you and the environment.

Our solar power panels systems cost between £5000 to £9000+ VAT, depending on the size and location of your home. This may seem expensive, but by installing a solar system we aim to reduce your electricity bill by up to 100%. Where else could you earn 9-13% per year tax-free on a low-risk investment, whilst protecting against rising energy prices and helping the environment at the same time.

Our solar panels are durable and come with a 25-30 year warranty. If well maintained, our solar panels can last for more than 30 years. Our solar panels are modern and blend well with any roof. A premium solar panel installation acting as your home’s own energy supply is likely to increase the value of your property.

Solar panels are largely maintenance-free. Over time, however, they may be affected by environmental factors – dead leaves, for example, may block sections of the panel. We recommend that solar panels are checked every few years to ensure maximum efficiency and cleaned once or twice a year.

Solar panels need sunlight to generate energy, so they do not work at night. However, you can install a battery to store excess electricity generation during the day to then be used later at night.

Negative electricity bills

Generating more energy than you use could turn your electricity bills negative.

The marginal cost of adding panels to a 4 kW solar system is negligible, you may as well use the space available and go larger.

Find out how much you could save with solar

Our cost and savings calculator can help you find the right solar specification for you and how much you could save!

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