Even after years of operational data, technical audits, and field failures, a surprising number of EPCs continue to overlook critical weaknesses in solar mounting structures. These failures rarely show up during commissioning — they surface quietly after 3, 5, or 8 years, when corrective action becomes expensive, disruptive, and sometimes irreversible.
This part of the series focuses on structural blind spots that EPCs still underestimate, despite claiming 25-year reliability on paper.
1️⃣ Corrosion Under Joints & Fasteners — The Invisible Failure Zone
Most EPCs evaluate corrosion resistance based on overall galvanization thickness, but real-world failures usually start at connection points:
Bolt holes
Clamped interfaces
Overlapping purlins
Module rail joints
These zones experience:
Micro-cracks during tightening
Zinc layer damage during transport or installation
Water retention and capillary corrosion
Because these areas are hidden beneath modules, corrosion progresses unnoticed until:
Fasteners seize
Rails deform
Torque values fail during maintenance
Ignored reality: A structure can pass coating standards and still fail at joints within 6–8 years.
“Modern EPCs increasingly rely on engineered solar structure design standards that define corrosion protection, section thickness, wind-load safety, and long-term structural performance — aspects clearly outlined in detailed technical documents such as the Sun Steel Solar Mounting Structure catalogue.”
Steel Fatigue from Cyclic Wind Loads (Not Extreme Wind)
EPC designs often focus on maximum wind speed events, but long-term damage is caused by repetitive low-to-medium wind cycles:
Daily gust patterns
Seasonal monsoon oscillations
Resonance in long-span purlins
Over time, this causes:
Micro-fatigue cracks near welds and bends
Progressive loosening of bolted connections
Rail sagging that misaligns modules
Most failures here are misdiagnosed as “installation issues,” when the root cause is inadequate fatigue modeling during design.
Long-term solar structure failures often begin at the steel level, where inadequate tensile strength or poor fatigue resistance under cyclic wind loads compromises the overall frame — reinforcing why high-quality TMT bars engineered for structural durability remain critical even in non-building applications like solar plants.
Over-Optimised Steel Sections to Reduce Project Cost
To win tenders, many EPCs still reduce:
-
Section thickness
-
Safety margins
-
Steel grade consistency
While this works structurally on Day 1, it leaves zero buffer for degradation caused by:
-
Corrosion loss
-
Mechanical wear
-
Foundation settlement
After a few years, the structure technically remains “standing” but no longer meets:
-
Alignment tolerances
-
Load redistribution safety
-
Module stress limits
This leads to hidden energy losses and long-term warranty disputes.
EPCs focusing only on upfront savings often underestimate how steel price volatility impacts lifecycle cost planning, especially when procurement decisions ignore market trends visible in regularly updated TMT price lists used across the construction and infrastructure sector.
Foundation–Structure Mismatch (Soil Reality vs Design Assumptions)
Foundation failures remain one of the least discussed but most damaging risks.
Common EPC shortcuts:
Using generic soil bearing values
Ignoring seasonal moisture variation
Assuming uniform compaction across sites
Resulting issues include:
Differential settlement
Tilt drift in tables
Stress concentration at column bases
Once foundations move, even the best-designed superstructure starts failing prematurely.
Solar panels last 25 years.
— SG Mart (@sgmart_official) December 24, 2025
Many mounting structures didn’t.
EPCs are now redesigning solar structures using lifecycle engineering, better steel & corrosion control.
Here’s what changed 👇https://t.co/KhSAZnnyQ4#SolarStructure #solarenergy #Maxwell #ViratKohli #APLApollo pic.twitter.com/Mz8F1GHn9Y
5️⃣ Thermal Expansion Neglect in Long Rows
India’s solar sites face large temperature swings, yet many designs still fail to accommodate:
Long rail expansion
Constraint locking at joints
Thermal stress transfer to modules
This causes:
Rail buckling
Bolt shear stress
Module micro-cracking over time
Thermal movement is slow, silent, and destructive — making it easy to ignore until damage becomes visible.
6️⃣ Quality Variability Across Supply Batches
Even when EPCs specify “approved steel,” inconsistencies across batches lead to:
Uneven galvanization adhesion
Variable yield strength
Different corrosion rates within the same plant
Over 25 years, this creates uneven ageing, complicating maintenance and replacement planning.
Why These Failures Persist
These issues continue because:
They don’t cause immediate collapse
They rarely appear during warranty periods
They’re difficult to trace back to design decisions
Yet they directly impact:
Plant uptime
O&M cost escalation
Asset valuation during refinancing or sale
What This Means for the Solar Industry
The next phase of solar infrastructure maturity isn’t about faster execution — it’s about engineering honesty.
EPCs that ignore these failures risk:
Higher long-term liabilities
Loss of developer trust
Bankability challenges in future projects
Those addressing them early will define the next generation of reliable solar infrastructure.
