When going solar, one of the most important considerations is the efficiency of the solar panels you choose. Solar panel efficiency refers to how much of the sun’s energy striking the panel is converted into usable electricity. The more efficient the solar panels are, the more power they will produce.

Understanding the key factors that affect solar panel efficiency can help you make informed decisions when shopping for a solar photovoltaic (PV) system. This blog explains what solar panel efficiency means, the different types of solar panel technologies, how efficiency changes over time, and tips for choosing high-efficiency solar panels in India.
What is Solar Panel Efficiency?

Quite simply, solar panel efficiency refers to the percentage of sunlight energy striking the panel that gets converted into electricity. For example, a 20% efficient solar panel takes the available solar irradiation that hits the panel surface and converts 20% of it into electrical energy.

Solar panel efficiency is determined in controlled laboratory settings under Standard Test Conditions (STC). STC specifies a temperature of 25°C and an irradiation of 1000 W/m2 with an air mass of 1.5 in the light spectrum. Real-world conditions rarely achieve STC consistently, so actual efficiency is typically lower than the lab ratings.

The key metric used to measure solar panel efficiency is “rated watts.” A 250-watt solar panel with 18% efficiency under STC can be expected to produce around 250 watts of usable AC power under ideal conditions.

What Factors Impact Solar Panel Efficiency?

Many variables influence the real-world energy output from solar PV systems, including:

• Solar irradiation – Panels produce more energy when receiving abundant bright sunlight. Production falls on cloudy days or when panels are shaded.

• Ambient temperature – Solar cells become less efficient as they get hotter. Cooler panels produce more power.

• Dirt/dust – A build-up of dirt, dust, snow, etc. on the panels blocks sunlight from reaching the solar cells.

• Equipment issues – Inverter inefficiencies, wiring losses, etc. reduce the system’s overall production.

• Angle/orientation – How panels are mounted and angled impacts the amount of direct vs. diffuse irradiation they receive.

• Partial shading – If part of a panel is shaded, it hampers the output of the whole panel. High daytime temperatures are commonly what limit solar efficiency levels in tropical regions like India. The key is finding panels engineered to minimize thermal performance losses.

Types of Solar Panel Technologies

All solar panels are made up of solar photovoltaic (PV) cells that convert sunlight into DC electricity. However, the arrangement, underlying chemistry, and physical structure of the cells differ across technologies.

Common solar panel options include:

• Monocrystalline silicon – Made from sliced wafers of uniform silicon crystal structure. The most efficient but relatively more expensive panels are available.

• Polycrystalline silicon – Made from cast square ingots of melted silicon. Slightly lower efficiency than mono-c-Si but cheaper per watt.

• Thin-film – Extremely thin panels of amorphous silicon, cadmium telluride, or CIGS semiconductors printed on glass, plastic, or metal. Lower efficiency but potentially better performance in higher temperatures.

• High-efficiency panels – Specialized mono-c-Si panels with higher conversion rates through improved cell arrangement and minimizing resistive losses.

In general, thick crystalline silicon panels (mono- and poly-) have efficiency levels of 15-22% while thin film panels are 8-13% efficient in real world conditions. High-efficiency panel technology has improved crystalline silicon efficiency above 22% (up to 25%) through enhanced solar cell design.

Tips for Choosing High Efficiency Solar Panels

Here are a few tips Indian homeowners should keep in mind when shopping for high efficiency solar systems:

• Carefully compare panel efficiency specs and temperature coefficients. Prioritize higher conversion rates and lower temp coefficient ratings.

• Look for product/power output guarantees – Choose reputable brands that provide long 25+ year efficiency guarantees.

• Consider high-efficiency panel technologies – Advanced mono-c-Si products with efficiency which provide excellent performance.

• Ensure proper panel orientation – Optimal tilt and azimuth alignment maximizes efficiency by capturing the most sunlight.

• Leave room for future panel upgrades – Inverter and other system components should be sized for additional panels down the road.

• Work with high-quality installers – An experienced solar company will correctly size panels and maximize efficiency.

As one of India’s leading Tier-1 solar brands, Waaree offers exceptional high-efficiency solar panels tailored specifically for Indian weather conditions. Waaree’s flagship mono-PERC solar PV panels are rated as “India’s Most Efficient”.

With over 30 years of solar experience and panels exported to many nations globally, Waaree delivers superb performance and unmatched reliability. All Waaree solar panels come standard with product warranties and linear power output warranties, protecting your investment.

To learn more about solar options for your home or business, contact Waaree today and visit our official website to speak with an energy advisor and request a custom solar proposal suited to your needs and priorities. Investing in solar pays dividends for decades to come through lower energy bills, a reduced carbon footprint, and excellent ROI from your PV system. Go solar with the leader in Indian solar manufacturing!