What types of photovoltaic panels are there?
Photovoltaic panels can be divided according to cell material, cell technology and module design. In practice, the home user should first check the available roof space, required kWp, panel efficiency, temperature coefficient, warranty and electrical compatibility with the inverter.
Basic division according to the material and method of production of the cell.
Technologies that reduce losses and increase module efficiency.
Construction features affecting durability, work in the shade and possible additional yield.
Comparison of types of PV panels
| Panel type | What is this? | Advantages | Defects | When to choose? |
|---|---|---|---|---|
| Monocrystalline | A panel made of silicon cells with a uniform crystal structure. | High efficiency, good choice for the roof of the house, wide availability. | Typically more expensive than older poly. | The most common choice for new home installations. |
| Polycrystalline | An older type of panel made of multiple silicon crystals. | Simple technology, sometimes low price. | Lower efficiency, larger surface area for the same power. | Rather older installations or very budget projects. |
| Thin film | Module made of a thin layer of active material. | Possibly interesting applications on large or unusual surfaces. | Lower surface efficiency. | Facades, large surfaces, unusual designs. |
| PERC | Improved cell technology with rear side passivation. | Good price, high availability, reasonable efficiency. | Technology being replaced in the premium segment by TOPCon/HJT. | Price/quality compromise. |
| TOPCon | Cell with passivated contact and tunnel layer. | High efficiency, a good choice when the roof is limited. | Often more expensive than simpler PERC. | When you want to fit more kWp on the roof. |
| HJT | Heterojunction: the combination of crystalline silicon and amorphous layers. | Very good temperature parameters, high efficiency. | Higher price. | Hot roofs, premium segment, long working horizon. |
| IBC | Electrical contacts moved to the back of the cell. | High efficiency and aesthetics. | Premium technology. | Small roof, high aesthetics, high budget. |
| Bifacial | Double-sided panel that can also produce from the back side. | Additional gain from light reflection. | On a dark pitched roof, the profit may be small. | Land, carport, bright flat roof. |
| Glass-glass | Panel with glass on the front and back. | Better cell protection, potentially greater durability. | More mass. | Long service life, solid roof structure. |
Monocrystalline, polycrystalline and thin-film panels
Monocrystalline panels
This is the most common choice for new home installations. They have high surface efficiency and work well where roof space is limited.
Polycrystalline panels
They were popular in older installations. Today, they usually lose to monocrystalline panels in terms of power per square meter.
Thin film panels
They make sense in specific projects, e.g. large surfaces, facades or unusual integration with a building. In a typical single-family house, they are less likely to be the first choice.
PV cell technologies: PERC, TOPCon, HJT and IBC
The word "mono-crystalline" alone is not enough. Two mono modules may have different efficiency, degradation, operation in heat and price.
| Technology | Characteristic | Pros | What to watch out for? |
|---|---|---|---|
| PERC | Mature technology with backside passivation. | Good price, wide availability. | Compare degradation and temperature coefficient. |
| TOPCon | Newer passivated contact technology. | Higher efficiency, a good choice for a small roof. | Check the warranty, manufacturer and price for Wp. |
| HJT | Heterojunction cell. | Good work in heat, high efficiency. | Usually higher price. |
| IBC | Contacts on the back of the cell. | High efficiency and aesthetics. | Segment premium. |
Bifacial, half-cut, full black i glass-glass
It reduces current losses and can improve the module's behavior in partial shading.
Can produce from the back side. The gain depends on the lightness of the substrate, light clearance and light reflection.
It may increase the durability of the module, but it is heavier. The roof needs to be checked.
Better aesthetics, but should not replace the assessment of technical parameters.
When does bifacial make sense?
Mostly on the ground, a carport, a bright flat roof or a structure with clearance. On a typical dark pitched roof, the rear side of the module receives little light, so the gain may be limited.
Parameters of PV panels that need to be checked
| Parameter | What does it mean? | Why is it important? |
|---|---|---|
| Power Wp | Panel power under STC conditions. | It determines the nominal power of the installation. |
| Module efficiency | How much solar energy does the panel convert into electricity on a given surface? | Crucial for a small roof. |
| Temperature coefficient Pmax | Power decreases for every 1°C increase in cell temperature above 25°C. | Important in the heat. |
| Annual degradation | The rate of decline in module power in subsequent years. | It affects production after 10, 20 and 25 years. |
| Product warranty | Guarantee for the physical durability of the module. | Not to be confused with the linear power guarantee. |
| Dimensions and weight | Module size and weight. | They decide how many panels will fit on the roof and whether the structure will bear the load. |
| Voltage and current | Electrical parameters of the module. | They must match the inverter, strings and MPPT ranges. |
How to choose the type of PV panel for your home?
The best panel depends on your roof constraints, budget and purpose of installation.
Choose a high-efficiency panel: TOPCon, HJT or IBC.
TOPConHJTIBCLook at the temperature coefficient Pmax. HJT often performs well on this criterion.
HJTTOPConConsider a bifacial, especially with light-colored foundations.
bifacialglass-glassThe proven mono PERC can have a good price/yield ratio.
mono MINThe most common mistakes when choosing photovoltaic panels
1. Selection only with the help of Wp
A 550W panel can be larger than a 500W panel. Compare power together with area and efficiency.
2. Ignoring the operating temperature
On hot days, the panel loses power. The temperature coefficient Pmax is important for a dark, hot roof.
3. Confusing bifacial with automatic gain
Bifacial only works well if the back side has access to reflected light.
4. Ignoring the weight of glass-glass panels
Glass-glass can be heavier. The roof structure must be checked before installation.
5. Failure to check the parameters for the inverter
The voltage, current and string pattern must match the inverter. This is important for high current panels and roofs with several slopes.
Glossary of terms
| Concept | Explanation |
|---|---|
| PV | Photovoltaics, i.e. photovoltaics. |
| Wp | Watt-peak, the power of the panel under standard test conditions. |
| STC | Standard Test Conditions: 1000 W/m², cell temperature 25°C, AM spectrum 1.5. |
| Panel efficiency | The percentage of solar energy converted to electricity in a given area. |
| Pmax temperature coefficient | A coefficient showing how the panel power decreases as the cell temperature increases. |
| Bifacial | Double-sided panel, capable of producing energy also from the back side. |
| Glass-glass | Module with glass on both sides. |
| Half-cut | Technology of dividing cells in half to reduce losses. |
FAQ
Which photovoltaic panels are best for your home?
For most homes, the best starting point is monocrystalline panels. If the roof space is limited, it is worth considering TOPCon, HJT or IBC.
Do polycrystalline panels still make sense?
Less common in new home installations. They may make sense at a very low price or in older systems.
Is TOPCon better than PERC?
It often has higher efficiency and better parameters, but profitability depends on price, warranty, degradation and manufacturer.
Is HJT more profitable than TOPCon?
HJT can have very good temperature parameters, but is usually more expensive. Profitability depends on the roof and the price per Wp.
Is it worth buying bifacial panels for a pitched roof?
Typically only when the back side of the panel has access to reflected light. On a dark pitched roof, the gain may be limited.
What to count next?
After choosing the type of panel, check how many modules will fit on the roof and what power of the PV installation makes sense: selection of photovoltaic panels and PV power calculator.
When planning an energy storage facility, also check: replacing the inverter with a hybrid one and hybrid inverter for LiFePO₄ 48V batteries.