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LIMITED QUANTITIES, BE HURRY – HEAT PUMPS AT DISCOUNT PRICES!
LIMITED QUANTITIES, BE HURRY – HEAT PUMPS AT DISCOUNT PRICES!
In our previous articles we have discussed solar energy as a strategic investment mixed solar power plant as a whole. Now it’s time to turn our attention to the most visible and perhaps best-known part of the system: the solar panel itself. While the panels may look the same on the surface, the technology inside them has advanced enormously in recent years. Choosing the right panel technology is one of the most significant decisions, directly affecting the production, durability and payback period of the entire power plant.
This guide will help you understand the differences between the panels on the market. We won't delve into complex physics formulas, but will focus on what the technological differences mean in practice for your roof and your electricity bill.
Expert perspective: The technical content of this article is written by Mika Aaltonen, Chief Designer at Renewe. With over 15 years of experience in the electrical and energy industry, he has seen the development of solar panel technology from the front line and knows how to distinguish the highest quality and most sustainable solutions on the market.
Two main silicon-based technologies currently dominate the market. Although both generate electricity, their manufacturing process and properties differ.
Monocrystalline panels (Monocrystalline) represent a more modern and efficient technology. They are made from a single, pure and uniform silicon crystal, which gives them their characteristic, uniform black color. Because the crystal structure is uniform, the movement of electrons within the panel is more efficient, which leads to a higher efficiency. In other words, a monocrystalline panel produces more electricity from the same surface area. They also work slightly better in hot conditions and in dimmer light, which is an advantage in Finland's variable weather conditions. Today, almost all high-quality installations are carried out with monocrystalline panels.
Polycrystalline panels (Polycrystalline) were previously more common due to their cheaper manufacturing process. They are made from multiple silicon crystals fused together, giving them a more uneven, bluish, and “patchy” appearance. Due to their non-uniform crystal structure, their efficiency is typically lower than that of monocrystalline panels. While they are still a viable solution, the larger surface area they require and their lower performance make them a less common choice for new, quality-focused projects.
The most important technical value of the panels is their efficiencyIt tells you, in percentage terms, how much of the solar radiation energy hitting the panel can be converted into electricity. The higher the efficiency, the more power (watts) the panel produces per square meter.
In practice, this is very important. For example, space is often limited on the roof of a private house. By choosing panels with a higher efficiency, you can fit a more efficient power plant on the same roof area, which produces more electricity and greater savings. While 10 years ago the typical efficiency was 14–16 %, in modern high-quality panels it is already over 21–23 %, the highest in mass production in 2025. solar panel has an efficiency of 24.4%. This technological leap has made solar energy more profitable than ever before.
How do I recognize a really good efficiency? A good panel combines high efficiency (often 22–24 % class) and a low temperature coefficient (e.g. −0.29…−0.34 %/°C). Why does this matter? Efficiency = a lot of power for a small area. Temperature coefficient = less power drop in summer → more kWh per year.
Beyond just the crystal structure, the performance of the panels has been improved through several innovations. When you look at the technical specifications of the panels, you will likely come across the following terms:
PERC (Passivated Emitter and Rear Cell) is now almost standard in high-quality monocrystalline panels. Simply put, it is a special reflective layer added to the back surface of the panel's cell. This layer "bounces" the light that has passed through the cell back into the cell, giving it a second chance to turn into electricity. This small but ingenious improvement increases the efficiency of the panel and improves its performance, especially in dim light at dawn and dusk.
TOPCon (Tunnel Oxide Passivated Contact) is the next generation development of PERC technology. It further improves the cell structure, reducing small energy losses and increasing efficiency even higher. TOPCon panels are currently the most efficient on the market and represent the cutting edge of technology.
Double-sided panels (Bifacial) are an innovation that is particularly suitable for ground installations and flat roofs. These panels are able to generate electricity from both sides. The front side collects direct sunlight, and the back side utilizes diffuse light reflected from the ground, roof or snow. Under the right conditions, this can increase the total production of the panel by up to 5–15 %.
P-type / PERC: common, mature technology; good price-performance ratio. More susceptible to LID/LeTID phenomena, temperature coefficient often slightly weaker.
N-type / TOPCon: newer generation; better efficiency, lower degradation (less LID/LeTID), often better Pmax temperature coefficient → more consistent production when hot.
Condensed selection: if the budget allows and the ceiling area is limited, N-type (TOPCon) is often the best “long-term” choice.
In addition to the technical characteristics, the quality of the panel is also reflected in its warranty terms. A high-quality solar panel always comes with two separate warranties:
Always make sure that the panels you choose are made by a well-known and reputable manufacturer and that they have the necessary international certifications (such as IEC and TÜV) that prove their quality and safety. Renewe only uses components from such market-leading manufacturers.
Tier 1 classification? This rating is a sign that the manufacturer is considered reliable and that you can be sure of the panel warranty – both in terms of power output and product components. Only a small percentage of all solar panel manufacturers reach the Tier 1 category. Tier 1 is an international and impartial rating (summary), which is granted only to solar panel manufacturers who have the financial and technical capacity to guarantee a 20–35 year warranty for their products.
The solar panel is solar glass motor. Although a cheaper and technically older panel may be attractive with a lower initial investment, it produces less electricity and its life cycle is often shorter. By investing in a modern, high-efficiency monocrystalline panel, you ensure that you get the best possible return on your roof and a system that will serve you reliably for decades.
What are the specific needs of companies when choosing panels? In commercial properties, the choice of panels directly affects the ROI of the investment. On large roof areas, the marginal efficiency improvement of TOPCon technology can mean additional income of thousands of euros annually. In ESG reporting, Tier 1 classified panels are a strong signal of responsibility. In industrial properties, double-sided panels can be the optimal solution for light flat roofs, where reflection maximizes the return.
It's also important to remember what this power is used for. When you can fit a more efficient power plant on your roof, it means more of your own, free energy. heat pump for running, electric car charging station for use or energy storage Higher efficiency is not just a technical number – it is a direct path to faster energy self-sufficiency and greater savings across the entire building's energy ecosystem.
Our mission at Renewe is to act as an expert filter and quality controller for our customers – we ensure that our selection includes only high-quality, classified and tested components suitable for Finnish conditions!
Book a free survey – We design the optimal panel solution for your property and provide a transparent cost-benefit estimate. Contact our experts, which will help you choose the most suitable and highest quality solar panels for your specific project.
How do solar panels withstand Finnish weather conditions, such as snow and frost? This is one of the most common and important questions, and the answer is clear: high-quality solar panels are designed and tested to withstand very harsh conditions. Their surface is made of tempered glass (or plastic) and the frame is made of sturdy aluminum, which can withstand both snow loads and frost without any problems. In fact, the efficiency of the panels is even slightly better in cool weather than in hot weather. Snow naturally covers the panels for part of the year, but in Finland the majority, about 90 %, of the annual production falls on the snow-free period from March to October. The installation angle helps the snow to run off, and at the latest the spring sun melts the rest, revealing a surface that has often been cleaned by rain during the winter and is ready for production.
Technology is constantly evolving – should I wait for even more efficient panels? It is true that solar panel technology is constantly evolving, but the pace of development is now more moderate than a decade ago. Modern, high-quality monocrystalline panels have already achieved very high efficiency and a long life cycle. Waiting for a possible improvement of a few percent in the future means losing out on the concrete savings you can make on your electricity bill today. It makes more sense to think about investing now: every month that the power plant on your roof is producing clean and free energy is a direct financial benefit. A high-quality system based on modern technology is a very profitable investment that starts paying for itself from the day it is installed.
What is the difference between a regular and a “Full Black” solar panel? The difference is mainly aesthetic, but it is very significant for many property owners. In a traditional solar panel, thin, silver-colored conductors are visible between the silicon cells and the panel is surrounded by an aluminum-colored frame. In “Full Black” panels, these conductors and the frame are made black, creating a uniform, stylish and unobtrusive black surface. This gives the power plant a very clean and modern look, and it blends in particularly well with dark roofing materials. The technical performance is practically identical to the high-quality basic models, so the choice depends primarily on the visual appearance you are aiming for for your property.
Can old panels be upgraded to new ones without replacing the entire system? Most of the time yes. If inverter and other infrastructure are in order, simply replacing the panels with newer technology is possible. This “repowering” can increase the system yield by 30-50% on the same roof area. Renewe always performs a compatibility analysis before upgrading.
