Flexible vs Rigid Solar Panels (and Everything In-Between): The Clear, Practical Explainer

What this guide covers (in plain English)

We’ll quickly explain every major solar panel type: rigid, flexible (semi-flexi), ultra-light glass-free, roof-integrated/slates/shingles, plus a nod to bifacial and emerging tech, then give you a no-fluff section on balcony solar (spoiler: flexible wins on balconies for weight and ease, but rigid rules roofs and gardens).

Quick physics check: panels are rated in watts (W), that’s power. Over time they produce energy measured in watt-hours (Wh). Flexible panels usually produce fewer Wh per day than rigid panels of the same footprint because they run hotter and are typically less efficient.

The Main Panel Types

1) Rigid “conventional” solar panels (best for most roofs & ground mounts)

• What they are: Crystalline silicon cells behind tempered glass with an aluminium frame (glass-backsheet or glass-glass).
  
• Why they’re popular: Highest real-world efficiency and durability, best £/W, longest warranties (often 25–30+ years).
  
• Watch-outs: Heavier; need racking/roof fixings; big panels can be awkward on small roofs.
  

Typical size & weight (modern ~400–430 W residential):

~1.7–1.8 m × ~1.0–1.13 m, ~18–23.5 kg (40–52 lb)

Best for: Pitched roofs, flat roofs with ballast, garden ground-mounts, carports.

2) Flexible & Semi-Flexible panels (best for curved or weight-limited surfaces)

• What they are: Ultra-thin laminates (often ETFE top sheet) using mono-silicon or thin-film (e.g., CIGS). Can bend gently and bond or strap to surfaces.
  
• Why people pick them: Very light, low profile, quick installs, great where rails/penetrations aren’t possible (vans, boats, lightweight roofs).
  
• Trade-offs: Shorter warranties on average, must respect bend radius, and they run hotter (less rear airflow) which means lower Wh/day than rigid panels of similar area.
  

Typical sizes & weights:

100 W flex: ~1.09 × 0.58 m × 3 mm, ~2.4 kg

200 W flex: ~1.60 × 0.75 m × 3 mm, ~3–5.0 kg

Best for: Campervans, boats, curved awnings, balconies and terraces where weight and simplicity matter most.

3) Ultra-light glass-free “rigid-ish” modules (the middle ground)

• What they are: Crystalline silicon on a composite sheet (no heavy glass). Bonded or lightly framed; building-grade in many lines.
  
• Pros: Big weight savings versus rigid glass; neat aesthetics; thin (≈2 mm).
  
• Cons: Pricier per watt; surface prep/adhesion matters.
  

Typical size & weight (≈430 W example):

~2.05 × 1.08 m × ~2 mm, ~6–8 kg

Best for: Low-load roofs, retrofits where rails are tricky, clean minimalist installs.

4) Roof-integrated PV, solar slates & shingles (beauty + power)

• What they are: Panels or PV tiles that replace the roofing material, sitting flush with the roof.
  
• Pros: Beautiful, planning-friendly in many areas, no external rails.
  
• Cons: Higher cost; slightly warmer due to lower airflow, so a touch less output vs above-roof arrays.
  

Typical notes:

In-roof kits (module-sized): similar panel footprint to rigid; overall roof weight like a normal roof + PV.

PV slates/shingles: come as smaller tiles (e.g., 500×300 mm class) at ~3–4 kg per tile; multiple tiles per m².

Best for: New builds, re-roofs, heritage/conservation aesthetics.

5) Bifacial panels (niche for homes, great for carports/ground)

• What they are: Glass-glass modules that collect light on both sides.
  
• Pros: Extra energy if the rear sees reflected light (bright ground, white roof, or elevated racking).
  
• Cons: Gains are site-dependent; often overkill for small domestic roofs.
  

6) The interesting “coming soon” bucket

Perovskite-silicon tandems, OPV films, transparent PV: rapidly improving and appearing in pilot products. For most DIY’ers today, proven silicon still offers the best mix of cost, reliability, and support.

Balcony Solar: What to Choose (and Why)

If you want a quick, affordable route to shave daytime usage—balcony/plug-in solar is brilliant. And for balconies specifically, flexible panels are usually the best choice.

Why flexible wins on balconies

• Weight: Flex panels are dramatically lighter than framed glass modules, so they’re friendlier to railings and easier to handle solo.
  
• Slim profile & lower wind load: Less “sail” effect, fewer sharp edges.
  
• Install simplicity: Strap to the railing or a light frame; no heavy racking.
  
• Portable: Move flat? Unstrap, roll gently or carry, and take them along.
  

Typical flexible balcony set-ups:

• 1–2 × 200 W flexible panels (≈ 1.60 × 0.75 m, ~4.5–5.0 kg each) + a microinverter sized for 300–600 W total.
  
• Add a smart plug/energy monitor so you can see savings and shift appliance use (dishwasher, washing, EV granny charge) into sunny hours.
  

Reality check on output:

Flex panels usually deliver less Wh/day than rigid panels of the same footprint because they’re less efficient and run hotter when flush to a surface. A small air gap helps cooling and boosts yield.

When rigid makes sense instead

• If you have a pitched roof (and permission) or garden space for a ground-mount, go rigid:
  
• More watts per square metre → more Wh/day and better lifetime energy.
  
• Longer warranties and tougher construction.
  
• Best cost per watt for budget-sensitive projects.
  

Safety & rules: Use certified gear, weather-rated cabling, and proper strain relief. Check your building/landlord rules and local electrical requirements (RCD/GFCI protection, dedicated plug/spur, notification—varies by region).

A 30-Second Decision Guide

Balcony / railing / strict weight limits? → Flexible (semi-flexi) panels with a small microinverter.

Pitched roof or garden space? → Rigid panels for the best Wh/day and ROI.

Curved skins or can’t penetrate the surface? → Flexible or ultra-light glass-free bonded modules.

Aesthetics first or conservation area? → Roof-integrated or PV slates/shingles.

Pro Tips from the Install Trenches

• Airflow is free performance: even a small gap behind a flex panel improves cooling and yield.
  
• Respect bend radius: one gentle curve at install; avoid repeated flexing.
  
• Shade is the silent killer: design around chimneys/railings; consider optimisers/microinverters on complex sites.