Intermittent Heating for PV Module Moisture Control

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Solution Overview

Problem

Photovoltaic modules in arid climates face significant performance loss due to dust accumulation caused by moisture condensation, which current cleaning methods and coatings are ineffective in addressing, and active heating is energy-inefficient.

Innovation Solution

A method using a controllable heating device that heats the surface based on real-time electrical conductivity measurements between electrodes to maintain optimal moisture levels, reducing condensation and dust adhesion with minimal energy input.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If regular cleaning is performed to remove dust from PV modules, then soiling losses are reduced, but system operating costs increase significantly

Engineering Contradiction:
Improvepower outputVSAvoidcleaning cost
Core Design Contradiction:
ProductivityVSUse of energy by stationary object

Solution Approach 1:

The heating device performs preliminary action by heating the PV module surface before dew formation occurs, preventing moisture accumulation that causes dust adhesion. This proactive approach avoids the need for subsequent cleaning operations, resolving the contradiction between maintaining power output and reducing cleaning costs.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention converts the harmful effect of heating (energy consumption) into a beneficial outcome by using minimal, targeted heating to prevent dew formation. This selective heating approach transforms what would be wasteful energy use into a cost-effective dust prevention strategy, reducing both cleaning costs and power losses.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

2Object-affected harmful factors

If active heating is used to prevent dew formation, then dust adhesion is reduced, but energy consumption increases

Engineering Contradiction:
Improvedust adhesionVSAvoidheating energy
Core Design Contradiction:
Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

The heating device applies partial action by providing just enough heat to prevent dew formation rather than continuously heating the surface. The controller activates heating only when dew formation is detected or predicted, using minimal energy while still effectively preventing dust adhesion, thus resolving the contradiction between reducing harmful factors and minimizing energy consumption.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The system employs periodic action by intermittently activating the heating device based on environmental conditions such as temperature and humidity. Rather than continuous operation, the heater is activated in periodic cycles only when necessary to prevent dew formation, significantly reducing energy consumption while maintaining effectiveness in preventing dust adhesion.

Inventive Principle:
Principle #19Periodic action

3Duration of action of stationary object

If glass coatings are applied to reduce dust adhesion, then cleaning intervals are extended, but effectiveness is lost when condensation occurs

Engineering Contradiction:
Improvecleaning intervalVSAvoidcoating effectiveness
Core Design Contradiction:
Duration of action of stationary objectVSReliability

Solution Approach 1:

The heating device performs preliminary anti-action by preventing dew formation before it can occur on the coated surface. By maintaining the surface temperature above the dew point, the system protects the coating's effectiveness and prevents the condition (condensation) that would otherwise cause the coating to fail, thus extending reliable cleaning intervals.

Inventive Principle:
Principle #9Preliminary anti-action

Solution Approach 2:

The system changes the temperature parameter of the glass surface by applying heat to keep it above the dew point. This parameter change prevents the phase transition of moisture that would cause dust adhesion, thereby maintaining the effectiveness of the hydrophobic coating and extending the duration until cleaning is needed.

Inventive Principle:
Principle #35Parameter changes

4Device complexity

If indirect temperature-based control is used for heating, then system complexity is reduced, but measurement precision is insufficient

Engineering Contradiction:
Improvecontrol systemVSAvoidsurface humidity detection
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent introduces an intermediary approach by using a simplified temperature-based control system that indirectly estimates surface humidity conditions. Rather than directly measuring complex humidity parameters, the system uses temperature as an intermediary indicator to trigger heating, achieving acceptable precision while maintaining low device complexity.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

Effectively reduces moisture formation and dust accumulation on photovoltaic modules with reduced energy consumption, minimizing cleaning costs and preventing potential-induced degradation.

Implementation Method 1

the surface is heated intermittently by a controllable heating device

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 2

an electrical voltage is applied between at least two electrodes applied to the surface at a distance from one another, or between an electrode applied to the surface and a component of the object that can be used as a further electrode on the surface

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 3

the temperature of the module surface drops below the ambient temperature (air temperature) due to heat radiation against the cold sky

Methodology Applied
Scientific EffectThermal radiation: Thermal Radiation

Implementation Method 4

dew formation often occurs at night or in the early morning hours before sunrise because, under clear weather conditions, the temperature of the module surface drops below the ambient temperature

Methodology Applied
Scientific EffectCondensation: Condensation

Data Source

PatentEP3837765B1Method and arrangement for reducing the buildup of moisture on a dielectric surface of an object
Publication Date: 2023.03.22 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP3837765B1 patent drawingFigure 1
  • EP3837765B1 patent drawingFigure 2
  • EP3837765B1 patent drawingFigure 3

AI summary

The invention relates to a method and to an arrangement for reducing the buildup of moisture on a dielectric surface of an object (6), wherein the surface is heated intermittently by a controllable heating means. Between at least two electrodes (7) applied to the surface with a spacing from one another, or between an electrode applied to the surface and a component of the object (6) which can be used as a further electrode on the surface, an electrical voltage is applied and a current flow over the electrodes (7) is detected and/or measured, in order to obtain a measure of the relative surface humidity. The heating device is then controlled or adjusted in accordance with the detected and/or measured current flow and a predetermined value of the current flow. The predetermined value of the current flow is selected such that the value corresponds to a relative surface humidity in the range from 50% to 70%. The method and the arrangement are outstandingly suitable for preventing PV modules from becoming wet, with low outlay in terms of cost and energy.