Physical and Installation Limitations

1) Weight and Roof Load Pressure

Rigid panels are relatively heavy (about 15–20 kg/m²). Old houses, lightweight roofs (e.g., wooden structures, tin roofs), or roofs with insufficient load-bearing capacity may not support direct installation. Structural reinforcement (e.g., adding beams) is required, increasing upfront costs and engineering complexity.

2) Space Occupancy and Layout Constraints

Although more efficient than flexible panels (18–22%), they still require sufficient continuous roof area. If the roof has skylights, chimneys, vents, trees, or neighboring building obstructions, the available installation area will be reduced. Small households or complex roofs (e.g., multi-slope attics) may not meet power demand.

3) Sensitivity to Roof Angle and Orientation

The optimal power generation efficiency of traditional panels depends on orientation (south-facing preferred)​ and tilt angle (usually consistent with local latitude). If the roof itself has a steep slope (e.g., steep-pitched roofs), deviates from south-facing (e.g., east-west), or is uneven (e.g., curved roofs), power generation will decrease significantly—unless adjustable brackets are added (further increasing costs and wind resistance).

Performance and Efficiency Limitations

1) Poor Shadow Tolerance

Traditional panels mostly use a “series string” design. When a single cell or part of a panel is shaded (e.g., by leaves, bird droppings, antennas), the current of the entire string drops sharply (“short-board effect”), resulting in a 30%–70% loss of power generation. In contrast, some flexible panels or new designs with “bypass diodes” can mitigate this issue, but traditional panels are more sensitive.

2) Temperature Dependence

Although rigid panels are more heat-resistant than flexible ones, the efficiency of semiconductor materials (silicon) still decreases with rising temperature (about 0.3%–0.5% per 1°C increase). In summer heat or direct sunlight, actual power generation may be 10%–20% lower than the nominal value.

3) No Power Generation Without Light

Inherently dependent on sunlight, they cannot generate electricity at night, on cloudy/rainy days, or in winter with insufficient light. Energy storage batteries (increasing costs) or grid power are required, making complete off-grid operation impossible.

Maintenance and Durability Issues

1) Cleaning and Maintenance Requirements

The glass surface easily accumulates dust, bird droppings, leaves, or snow. Long-term lack of cleaning reduces efficiency (dust shading can reduce power generation by 5%–15%, worse in dry/dusty areas). Cleaning requires manual or professional equipment, with safety risks for high-rise roofs.

2) Extreme Weather Risks

Although meeting hail resistance standards (usually withstanding 25mm-diameter hail at 23m/s), extreme weather (e.g., tornadoes, typhoons, severe hail) can still damage glass or frames. Salt spray corrosion in coastal areas may accelerate aluminium frame aging.

3) Immovability

Once installed, panels are permanently fixed to the roof. If the homeowner moves, they cannot take the panels (removal costs may be 30%–50% of initial installation) and can only leave them for the new owner or transfer them at a low price, far less flexible than portable or flexible panels.

Cost and Economic Limitations

1) High Initial Investment

Including panels, inverters, brackets, labor, and grid connection approval, the total cost is usually 2,000–3,000 USD/KW (for domestic), which is a barrier for budget-limited families. Although long-term electricity savings are available, the payback period is 5–10 years (dependent on electricity prices and policy subsidies).

2) High Costs for Removal and Reinstallation

If the roof needs repair or replacement (the most common reason for removal), panels must be professionally removed (to avoid roof damage). The reinstallation cost after repair may account for 20%–40% of the initial investment. If reinstallation is abandoned, the upfront investment becomes a “sunk cost.”

3) Dependence on Policy and Market Fluctuations

Economy highly relies on government subsidies (e.g., tax credits, feed-in tariffs) and grid “net metering policies” (allowing selling excess power to the grid). If policies are scaled back (e.g., reduced subsidies, lower feed-in prices), the payback period will extend, even affecting investment value.

Aesthetic and Regulatory Constraints

1) Aesthetic Controversies

Some homeowners believe the “industrial feel” of traditional panels ruins the original aesthetics of their homes (especially historic buildings, high-end residences, or design-focused communities), which may cause neighborhood disputes or violate homeowners’ association (HOA) rules.

2) Building Code Restrictions

Some areas have strict regulations on the installation height, area ratio, and fire rating of rooftop PV (e.g., banning installation in historic preservation areas or requiring panels to be flush with the roof), limiting installation options.

Other Considerations

Slow Technological Iteration: Traditional panel technology is mature but updates slowly. If higher-efficiency new products emerge a few years after installation, upgrading requires replacing the entire system rather than partial optimization.

Grid Compatibility: In old residential areas with insufficient grid capacity, large-scale panel grid connection may cause voltage fluctuations, requiring additional voltage stabilization equipment.