Hand-Powered Photovoltaic Module Hoist Ladder Sled
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Solution Overview
Problem
The existing methods for lifting photovoltaic modules onto building roofs are either expensive, unsafe, or ergonomically undesirable, as they often require large motorized hoists or involve manual rope pulling, which can be hazardous and inefficient.
Innovation Solution
A hand-powered photovoltaic module hoist system comprising a sled that slides along a ladder with a pulley assembly and a safety release cord, allowing for manual operation and secure lifting of modules, along with an optional adjustable roof standoff for stability on various roof geometries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large motorized hoists or cranes are used to lift photovoltaic modules, then lifting capacity and safety are improved, but installation cost and system complexity increase significantly
Solution Approach 1:
The hoist system is divided into separate modular components: a sled that slides along the ladder, a pulley assembly mounted at the top, and a separate locking mechanism. This segmentation allows each component to be optimized independently and simplifies the overall system compared to integrated motorized hoists.
Solution Approach 2:
A ladder is introduced as an intermediary structure to support the sled during module transport. The sled slides along the ladder rails, providing a guided path that ensures safe module transport without requiring complex motorized positioning systems.
2Power
If large motorized hoists are used to lift photovoltaic modules, then lifting capability is improved, but installation cost increases
Solution Approach 1:
The system uses the installer's own body weight and manual pulling force on the rope to provide the lifting power. The pulley assembly mechanically amplifies this manual force, eliminating the need for external motorized power sources and reducing equipment costs.
Solution Approach 2:
The sled is designed to slide along the ladder at a consistent elevation, maintaining equipotential conditions that reduce the effort required to lift modules. The gradual incline of the ladder distributes the lifting work over a longer distance, reducing peak force requirements.
3Ease of manufacture
If modules are lifted manually up a ladder without a hoist, then equipment cost is reduced, but safety deteriorates due to risk of dropped modules
Solution Approach 1:
The sled incorporates a cradle structure that beforehand secures the module in position during transport. The module is held in place by the sled's contoured surface and side walls, preventing it from shifting or falling during the lifting process.
Solution Approach 2:
The module nesting feature allows the sled to cradle the module securely, with the sled's internal geometry nested to match the module's external dimensions. This nested configuration provides inherent safety without requiring additional restraining mechanisms.
4Ease of manufacture
If modules are pulled upward with a rope, then equipment cost is reduced, but safety and ergonomics worsen in high winds
Solution Approach 1:
The dangerous function of directly pulling modules with a rope is extracted and replaced by a sled that slides along the ladder. The rope only needs to pull the lightweight sled, while the sled's structure bears the load of the module, separating the lifting function from the securing function.
Solution Approach 2:
The sled acts as an intermediary between the rope and the module. Instead of the rope directly contacting and pulling the heavy module, the rope pulls the lightweight sled, which in turn moves the module along a guided path, reducing the risk of loss of control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system provides a safe, cost-effective, and efficient means to lift photovoltaic modules onto roofs, reducing the risk of module damage and installer fatigue, while being adaptable to different roof configurations and module sizes.
Implementation Method 1
a pulley assembly mounted at the top of the ladder
Implementation Method 2
a sled that slides up and down along a ladder
Data Source
AI summary
A hand-powered photovoltaic module hoist having a sled that slides along a ladder, and a pulley assembly mounted at the top of the ladder with a first cord to lift the sled and a second safety release cord to permit the sled to descend down the ladder. The sled is not attached to the ladder and the pulley assembly is a removable frame that is hung onto rungs of the ladder such that the hoist can quickly be installed on a standard ladder.