Heckert Solar photovoltaic modules “Made in Germany” combine high quality with a fair price, creating strong demand and highly satisfied customers. Many Asian manufacturers have also established themselves in the market thanks to reliable quality and excellent value for money, offering strong alternatives at a lower price point. Here you will find modules from brands such as Trina, LONGi, Jinko, JA Solar, or Aiko Solar.
The following key criteria will help you compare solar modules:
Efficiency
Efficiency indicates what share of the sunlight hitting the PV module is converted into electricity. The higher the efficiency, the more electricity is generated per m² of module area. If you have enough space available to achieve the desired PV capacity, more affordable solar modules with a lower efficiency can still be a sensible alternative. In general, efficiency—like price—is closely linked to the cell technology used in today’s half-cell modules and typically ranges from 20% to 24%.
Certification and Testing
Modules tested and certified in accordance with the IEC EN 61215 standard have proven to be stable and reliable during the test procedure. The certification is listed in the module’s datasheet. In addition, all modules are tested for mechanical load capacity under snow loads and for hail resistance. The datasheet usually provides this information as well.
Product Warranty
Most manufacturers offer a product warranty of at least 15 years. Check whether the warranty is backed by an insurance provider, and look into the manufacturer’s registered office to get a sense of whether warranty claims can realistically be enforced. If in doubt, choose manufacturers you can reasonably expect to still be in business many years from now.
Performance Warranty
The performance warranty states the maximum power loss the solar module is allowed to have over its lifetime. In most cases, manufacturers guarantee at least 90% of the rated output after 10 years and 80% after 25 years. Since the customer must prove that the module is underperforming, it also makes sense here to take a closer look at the warranty terms and conditions.
Modules with monocrystalline cells
Monocrystalline solar cells are made from a single, highly pure silicon crystal. In a complex process, a cylindrical single crystal—known as an “ingot”—is formed and then sliced into thin wafers (approx. 0.2 mm). The wafers are then cleaned, doped, coated with an anti-reflective (AR) layer, and assembled into a solar module. Despite the elaborate manufacturing process, monocrystalline PV modules have become the affordable market standard. They perform very well in low-light conditions and currently offer the highest efficiency, which means you need less roof area to generate a high amount of electrical energy. Today, almost every solar cell used on the market is monocrystalline.
N-type vs. P-type: What’s the difference?
“N-type” stands for negative-type (negatively doped) solar cells. These are solar cells in which the semiconductor is doped with negatively charged electrons. Compared with P-type (positively doped) cells, N-type cells offer several advantages—this is why they have increasingly become the market standard:
PV modules with PERC solar cells
PERC (Passivated Emitter and Rear Cell) solar cells increase efficiency by adding a passivation layer on the rear side that reflects more light back into the cell for a second pass. This boosts light yield and reduces energy losses caused by recombination. While PERC-based solar modules are very cost-effective, they are increasingly being replaced on the market by newer technologies.
Solar modules with heterojunction cell technology (HJT)
Heterojunction technology combines two semiconductor materials (e.g., crystalline and amorphous silicon) with different properties. This structure improves efficiency by reducing recombination losses and enabling more effective energy conversion.
TOPCon modules – today’s market standard
TOPCon stands for “Tunnel Oxide Passivated Contact”. It is a solar cell technology used to passivate contacts (typically on the front side), with the core goal of minimizing charge-carrier recombination at the contacts. Advantages of TOPCon solar cells include:
PV modules with back-contact solar cells – the latest technology
Back-contact cells have no silver busbars on the front side. You’ll find them under abbreviations such as IBC technology (“Interdigitated Back Contact”), LONGi’s HPBC technology (“Hybrid Passivated Back Contact”), or AIKO’s ABC technology (“All Back Contact”). The conductive contact fingers that carry the current away from the cell are installed exclusively on the rear side. This offers several advantages:
Glass-glass modules are a special type of solar module in which both the front and the rear side are made of glass. Compared to conventional solar modules with a polymer backsheet, these dual-glass modules offer a range of advantages and are increasingly becoming the standard:
Tip for choosing dual-glass modules
Dual-glass modules are currently available with different glass thicknesses. You can find modules with 2× 1.6 mm glass and with 2× 2.0 mm glass. If you want even more stability and durability, look for the 2× 2.0 mm option.
Glass-glass modules can be bifacial. This means the cells are also exposed on the rear side and can generate electricity when light hits the back of the module.
Some glass-glass modules only have white or black foil in the gaps between the individual cells. These are also bifacial. Some glass-glass modules, however, have a full-area backsheet/foil behind the cells (between the glass layers) and are therefore not bifacial—those modules have a white or black rear side.
PV modules with back-contact solar cells – the latest technology
Back-contact cells have no silver busbars on the front side. You’ll find them under abbreviations such as IBC technology (“Interdigitated Back Contact”), LONGi’s HPBC technology (“Hybrid Passivated Back Contact”), or AIKO’s ABC technology (“All Back Contact”). The conductive contact fingers that carry the current away from the cell are installed exclusively on the rear side. This offers several advantages:
Modules are installed in series-connected “strings”. The module with the lowest output in a string—like the weakest link in a chain—sets the maximum performance for all other modules in that string. If long shadows stretch across the roof or unfavorable orientations threaten to reduce yield, power optimizers can offer a solution. They lower the voltage of the weaker modules in a string while increasing their current to match the level of the better-performing modules. Additional benefits include monitoring individual modules and enabling complex layouts and different orientations. Read more here
Don’t want to go through the effort of choosing solar modules and a matching inverter yourself? Then take a look at our complete systems! We’ve already put together a selection of PV systems where the solar modules and the inverter are perfectly matched.
Still not sure which PV module to choose? Then get in touch with us! With hands-on experience and in-depth market knowledge, we can help you even with individual requirements and special cases. Or fill out our request form and we’ll create a quote tailored to your needs. We offer solar modules that match your expectations.
