Photovoltaic BIPV Waterproof System

BIPV (Building Integrated Photovoltaics) is a technology that integrates solar photovoltaic modules with building envelopes (such as roofs, curtain walls, sunshades, etc.). Its core is to allow photovoltaic modules to simultaneously undertake the dual functions of "power generation" and "building envelope". The waterproofing system is a key subsystem of BIPV, which is directly related to building structural safety (preventing water leakage from damaging the building), photovoltaic module life (avoiding moisture and short circuits), and power generation efficiency (reducing downtime due to failures).

Keyword:

Advisory hotline: +86-22-68287199

Classification:

Photovoltaic overall solution

Technical documentation:

chenwei@tkoisteel.com

Consulting

Details Introduction

BIPV (Building Integrated Photovoltaics) is a technology that integrates solar photovoltaic modules with building envelope structures (such as roofs, curtain walls, sunshades, etc.). Its core is to allow photovoltaic modules to simultaneously undertake the dual functions of "power generation" and "building envelope". The waterproofing system is a critical subsystem of BIPV. , which is directly related to building structural safety (preventing water leakage from damaging the building), photovoltaic module lifespan (avoiding moisture-induced short circuits), and power generation efficiency (reducing downtime due to failures). The following provides a detailed introduction from the aspects of importance, design principles, system types, core components, and construction key points:

I. Core Importance of BIPV Waterproofing System

The connection points between BIPV modules and the building structure, and the seams between modules, are high-risk points for rainwater penetration. If the waterproofing fails, it can lead to:

Building safety hazards : Rainwater seeps into the building interior, corroding steel bars and walls, reducing structural durability;
Photovoltaic system damage : Moisture-induced short circuits inside the modules, circuit failures, sharp drops in power generation efficiency, or even scrapping;
Surge in maintenance costs : Leakage repair requires the removal of some modules, which not only affects power generation but may also damage the original waterproofing structure, creating a vicious cycle.

II. Design Principles of BIPV Waterproofing System

BIPV waterproofing needs to consider both "building waterproofing" and "photovoltaic function". The following principles should be followed during design:

Synergy : Matching the building's main waterproofing level (such as GB 50108 "Technical Specification for Waterproofing of Underground Works"), while adapting to the installation method of photovoltaic modules (such as flat laying, inclined laying, embedding, etc.);
Multi-level protection : Adopting a "prevention and drainage combination" strategy -- prioritizing the prevention of rainwater infiltration through sealing and structural design, and timely draining a small amount of infiltrated rainwater through drainage structures to avoid water accumulation;
Weather resistance and compatibility : Materials need to be resistant to ultraviolet radiation, high and low temperatures (-40℃~80℃), and wind and rain erosion, and be compatible with photovoltaic modules (glass, metal frames) and building structures (concrete, metal roofs) to avoid chemical corrosion or physical aging;
Maintainability : Reserve inspection and maintenance channels during design (such as openable module units) to avoid damage to the waterproofing structure due to maintenance.

III. Common BIPV Waterproofing System Types (Classified by Installation Scenario)

The main installation scenarios for BIPV are roofs and curtain walls , and the waterproofing systems for the two differ due to different stress and drainage directions:

1. Roof BIPV Waterproofing System

Roofs are the most common application scenario for BIPV (such as flat roofs, pitched roofs, metal roofs). The core of waterproofing is to "prevent rainwater from penetrating into the roof structure layer" and to cooperate with drainage design.

Flat Roof BIPV ：
Photovoltaic modules are usually elevated by brackets or directly attached to the roof waterproofing layer. Waterproofing focuses on:

Sealing between the module and the roof base: using butyl tape and waterproof membranes (such as TPO, PVC) to cover the gaps between the module edges and the roof;
Connection points between the bracket and the roof: sealing with waterproof gaskets (such as EPDM rubber) and sealing rings to avoid water leakage after bolts penetrate the roof waterproofing layer;
Drainage design: reserving a 5°~10° slope between modules, and using aluminum alloy water guides to direct rainwater to the roof drainage outlets.

Pitched Roof BIPV ：
Often combined with tiles (such as asphalt shingles, ceramic tiles), the waterproofing focus is on "the overlap between modules and tiles" and "eaves drainage":

Laying a waterproof underlayment (such as SBS modified asphalt membrane) under the modules as a second line of defense;
The overlap length between the module and the tile is ≥100mm, and the overlap is sealed with weather-resistant sealant;
Set up water barriers and drainage channels at the eaves to prevent rainwater from seeping into the eaves along the lower edge of the module.

Metal Roof BIPV ：
Photovoltaic modules are directly fixed on the metal roof panel (such as color steel plate). The waterproofing uses the "bite-type structural waterproofing" characteristics of the metal roof itself:

The connection point between the module and the metal plate adopts a special metal clamp, which is sealed with butyl tape to avoid damaging the bite edge of the metal plate;
The seams between the modules are aligned with the crest/trough of the metal plate, and the drainage slope of the metal plate is used to guide rainwater away.

2. Curtain Wall BIPV Waterproofing System

Curtain wall BIPV (such as glass curtain walls, stone curtain walls integrated with photovoltaic modules) is installed vertically or obliquely. The risk of rainwater penetration is lower than that of roofs, but it is necessary to prevent rainwater from seeping into the room along the module seams. Waterproofing focuses on:

Module joint sealing : Adopting a double sealing design -- using structural adhesive on the inside (to bear the force), and weather-resistant sealant on the outside (to prevent rainwater). The glue seam width is ≥5mm, and the depth is 1/2~2/3 of the width (to avoid three-sided bonding causing cracking);
Connection between frame and building structure : A gap is reserved between the curtain wall frame and the wall, filled with fireproof rock wool, and the outside is sealed with waterproof sealant + metal cover, and a drain hole is set on the inside (to drain a small amount of infiltrated rainwater);
Corner and opening sash treatment Add waterproof gaskets at the internal and external corners, use multiple seals (such as EPDM rubber strips) for the opening sash (such as openable photovoltaic modules), and set up drainage grooves to direct rainwater to the outside.

IV. Core Components of BIPV Waterproof System

Regardless of the scenario, the BIPV waterproof system consists of Sealing system 、 Drainage system 、 Structural waterproofing Three core components:

Components	Core functions	Common materials / structures
Sealing system	Prevent rainwater from directly penetrating joints / connection points	Silicone weather-resistant sealant (UV resistant, high and low temperature resistant), butyl tape (strong initial adhesion, long-term sealing), waterproof gasket (EPDM rubber, for bracket connection points)
Drainage system	Discharge a small amount of infiltrated rainwater to avoid water accumulation	Aluminum alloy water guide trough (roof), drainage holes (curtain wall frame), slope design (≥3°, to ensure water flow direction)
Structural waterproofing	Use the physical form of components / building structure for leak prevention	Component overlapping design (overlapping length ≥50mm), metal occlusal edge (similar to metal roof), drainage of profiled plate crest

V. Key Points for Construction and Maintenance

Construction control ：

The base layer needs to be cleaned (remove oil, dust) before the sealant is applied to ensure it is dry and to avoid air bubbles or false adhesion;
The components must be installed flat and the joints aligned to ensure that the sealant / overlapping parts are evenly stressed;
The drainage slope should be strictly implemented according to the design (such as roof ≥3°, curtain wall vertical drainage channel slope ≥1%).

Maintenance management ：

Regularly check whether the sealant is cracked or aging (recommended every 2~3 years) and repair or replace it in time;
Clean debris (such as fallen leaves, dust) from the drainage channel / holes to ensure smooth drainage;
Protect the original waterproof structure and reseal the joints when replacing components.

Summary

The BIPV waterproof system is a key link between "building protection" and "photovoltaic function". Its design needs to be combined with the characteristics of the scene, and multiple protections of "sealing + drainage + structure" should be adopted. The materials need to meet weather resistance and compatibility, and the construction and maintenance need to be refined control. Only in this way can we ensure that The BIPV system operates safely and efficiently for a long time

None

Angle Chi photovoltaic integrated tile

None

Angle Chi photovoltaic integrated tile