How to Choose your Solar Panels based on Solar Panel Efficiency

Before you buy your solar panels, you need to familiarize yourself with the term, solar panel efficiency. It is actually one of the most important qualities of solar panels because it’s what measures their performance. What this means is, it’s the rate at which solar energy is captured and converted into electrical energy. So what are the criteria for determining a solar panel’s efficiency?

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Image by OpenClipart-Vectors from Pixabay

STANDARD TEST CONDITIONS of Solar Panels

Before we begin, you should know that solar panels have certain baselines for comparison against other solar panels. These are called Standard Test Conditions. They include a temperature of 25 degrees Celsius and an irradiance of 1,000 W/sqm. Irradiance is “the amount of light energy from one thing hitting a square meter of another each second” (as defined by NASA). So, for example, one solar panel with an efficiency rating of 17% with a 1 square meter surface area would produce 170 watts. Another may have an efficiency rating of 15% with the same surface area, but would only produce 150 watts. So, the one with a higher efficiency rating would be considered better, under the same conditions.

MATERIAL, CONFIGURATION AND SIZE

But there are other factors to consider because different companies manufacture solar panels. Mostly, what matters here is the solar cell type. They vary in material, configuration and size, among other factors. Let’s take a look:

MATERIAL

• The most basic solar panels are Polycrystalline or Monocrystalline. Their base material is silicon.

CONFIGURATION

• Newer technology which improved the classic mono and polycrystalline solar cells resulted in PERC solar cells. Short for “Passivated Emitter and Rear Cell” or “Passivated Emitter and Rear Contact”, this variant has an added dielectric passivation layer on its rear to achieve higher energy conversion.
• N-Type — Negatively charged Silicon doped with Phosphorous, offers higher performance and lower rate of light-induced degradation
• HJT — Heterojunction solar cells use N-type crystalline silicon with added layers of amorphous silicon on both sides of the cell. These materials absorb different wavelengths of light, boosting cell efficiency to as much as 21.7%
• IBC or Interdigitated Back Contact Cells are the latest, most expensive monocrystalline silicon cells to date because they have the highest efficiency rating (above 22%) among all solar panels.
• Bi-facial — Dual sided panels and cells to produce more energy
• Split cells — Solar panels that are “cut” in half or in thirds to facilitate better electrical conversion
• Shingled cells — Solar cells that are cut into strips and then overlaid to form electrical connections.
• Multiple busbars (MBBs) — Busbars conduct electricity between cells in a solar panel. Multiple busbars decreases the distance that the current has to travel.

For a better visual understanding, let’s refer to this graphic from www.cleanenergyreviews.info. You will see the difference in efficiency ratings as you move from the classic to the newer designs of solar cells and panels.

SIZE

• Common solar panel sizes range from 60 cells to 78 cells, and double that, in half-cut solar panels.
• Larger panels using large cells create a larger surface cell area that increases efficiency and boosts power output
• Half-cut panels double the number of cells within the same surface area. It boosts efficiency because half-cut panels have lower resistive losses and a lower temperature co-efficient.

OPERATIONAL EFFICIENCY

Now, after all that high-brow explanation on the kind of solar panels you’re possibly getting, you also need to consider their operational efficiency in the real world. The Standard Test Conditions are good for comparing solar panels. However, there are other factors that can impact your solar panel efficiency, regardless of the type of solar panel you have, such as the following:

• Irradiance — there are times when the sun’s light is dimmed so there’s hardly any light to collect.
• Shading — Any shading over your solar panels, contributes to a decreased irradiance level. When the system becomes shaded, the solar panels have a decreased output.
• Panel orientation — When your roof solar panel does not face the sun, what good does it do?
• Temperature — An ideal environment for your solar panel is when it’s bright enough to capture a lot of solar energy but not too hot that it decreases the power output.

WHICH DO YOU GO FOR?

So now you have to decide which way you’re going to go. Do you go for the more expensive yet more efficient solar panels? It would be nice if cost wasn’t an issue. Do you go for the larger panels? It would be nice if your roof can accommodate the size of the panels. Or are you too confused now to even make a choice because there seems to be too much information?

It’s okay. If that’s the case and you can’t decide on what you want or if you need more information about these high-quality solar panels, don’t hesitate to send us a message on Facebook or visit our Ask Solar Mike website.

If you’re interested in accurately computing your solar panels requirement, schedule a call with us and you’ll be on your way towards your solar panel journey.

Originally published at http://blog.asksolarmike.com on June 3, 2021.