Solar panel efficiency might seem like a big thing, but it’s used for promoting a certain brand and marketing. Higher solar efficiencies can mean that their sellers will charge more for them. This is a loss for homeowners who have to pay exorbitant amounts of money to buy solar panels with greater efficiency.
Solar Panel Efficiency
Solar panel efficiency is the amount of conversion of sunlight into usable electricity by the solar panels. For example, a solar panel's efficiency of 20% means that 20% of the sun captured by the solar panels can be converted to electricity.
Factors Affecting Solar Panel Efficiency
Things projecting a shade or blocking any part of a solar panel can impact its efficiency. This includes debris, shading, dirt, dust, and snow. However, the real efficiency of solar panels is determined by the materials that make them.
Monocrystalline solar panels are used for homes since they’re more efficient than other solar cell types. However, even in monocrystalline solar cells, other varieties are more efficient than the traditional ones.
Solar cells that might be more efficient than monocrystalline solar cells are PERC, HIT, and half-cut solar cells. In half-cut solar cells, solar cells are sliced in half to decrease the resistance and increase power generation.
Other technologies include multi-busbar technology. This technology uses many ultra-thin wires to transfer electricity through the cells. Thin wires mean that there will be less shade on the panel’s surface.
They can capture more sunlight and have increased power production. Cooler panels tend to give an increased energy output; you can do that by placing a white back sheet behind the panels.
Calculation
The solar panel efficiency is listed on the specification sheet of a solar panel. This efficiency is measured in a lab under Standard Test Conditions (STC). Your actual efficiency will be different than the ideal efficiency measured in a lab. The conditions for the lab are constant while your home receives irregular sunlight, and the weather is different every day with varying temperatures.
Solar irradiance is the measure of energy from the entire disk of the Sun. If you can measure the solar irradiance levels in your area and know about them, then you can figure out the efficiency of your solar panels. The efficiency is measured in three steps:
- Multiplying the irradiance level in your region by the area of your solar panel.
- Divide the power rating by the answer in the first step.
- Multiply the answer in step two by 100, and you’ll have the estimated efficiency of a solar panel in your area.
Average Efficiency Now
Nowadays, solar panels have efficiencies in the range of 16%-20%. Certain solar panels have more than 20% efficiency, but they are mostly premium panels with a higher cost. It may seem little, but most things today have low premium efficiencies. For example, car engines have efficiencies in the range of 12%-30%. The highest efficiency in solar panels is 22.8%.
Efficiency Affecting Installation Cost
The installation cost is dependent upon solar panel efficiency. Premium solar panels have higher efficiencies and are usually priced at $0.15 more per watt. China is gaining popularity in the solar panel market too. Today, we can see high-efficiency panels made by Tier 1 Chinese manufacturers, like Trina Solar. China is selling highly efficient solar panels at lower prices, which will significantly impact the market.
The Importance Of Efficiency
In this economical and competitive world, brands love to show higher efficiency to boost sales and defeat their rivals. However, the importance of efficiency lies only in marketing. This only benefits the brands, and homeowners have to suffer the repercussions when they purchase solar panels with higher efficiencies at an increased price.
The power rating or the wattage matters. Efficient solar panels have higher energy outputs. Finding a solar panel with lower efficiency and greater power output is impossible. The wattage also acts as a limit to the energy production of solar panels. For example, two solar panels are rated at 350 watts.
One has an efficiency of 18% and the other 20%. However, both will generate 350 watts of power. A smart person would go for a solar panel with an efficiency rating of 18% as it will have a lower price.
Reason For Buying Highly Efficient Solar Panels
Efficient solar panels are useful if you have limited roof space because you can’t fit many solar panels on a small roof, so you need panels that will produce the same amount of energy but take up less space.
So you’ll likely have to find solar panels with a higher power rating since that usually means increased efficiency. This way, you can get highly efficient solar panels which will seem costly at first, but they will produce energy that can offset your bills and investment in them, so it’s a win-win for you.
Things To Look For Other Than Efficiency
The first thing you should look for is power output. The more power output you have, the fewer solar panels you’ll need to meet your energy needs. You should also look at performance warranties.
Performance warranty is the amount of power your panel will be able to generate as it gets older if we go by the average 25-year lifespan. You should expect a degradation rate of 2% in the first year and 0.5% for the rest of the years.
Temperature coefficient ratings and power tolerance are important things too. They specify how your solar panels will operate in real-world conditions. Good temperature coefficient ratings lie between -0.3% and -0.5% per degree celsius, while power tolerance ratings of -0/+5% are considered normal.
Lastly, you should check out the cost of the system when selecting solar panels. Contacting different solar installers to get multiple quotes is a good idea. You will better understand the price of other brands in your area.
Don’t be fooled by highly efficient panels, as sellers want to make more money by branding and selling them. Instead, you should check out the warranty and performance specifications.