Testing Solar Panel/Installation Coolant

Solar panel installations in industrial applications generally require coolant. This specialized coolant (and even water coolant) does need to be tested regularly by an accredited lab in order to maintain performance and prevent damage. There are three types of industrial solar installations that require coolant and testing.

1. Hybrid Solar Panels (PV/T Systems): These combine photovoltaic panels with thermal/heat collectors that recover waste heat from solar cells. A liquid coolant (usually water or glycol) circulates around the PV cells; removing excess heat and capturing it for other industrial purposes such as heating water. This process also improves electrical efficiency. PV/T systems are common in commercial settings with high hot water demand.

2. Concentrated Photovoltaic (CPV) Systems: These usually, but not always require coolant. They employ lenses or mirrors to concentrate sunlight onto high-efficiency PV cells (often multi-junction cells)—resulting in very high temperatures. Active cooling with liquid (or forced-air systems) is required to prevent damage and efficiency loss. Primary applications are utility-scale solar farms in hot, sunny climates and, due to their high efficiency, research and aerospace industries.

3. Experimental/Industrial High-Efficiency Panels: Used in fields that include spacecraft, military, and advanced research, these may require coolant. Cooling ensures optimal efficiency and thermal management under extreme loads or conditions. These coolants may involve liquid loops, phase-change materials, or thermoelectric cooling.

TYPES OF LIQUID COOLANTS USED IN SOLAR PANEL SYSTEMS

Water is the most common coolant used in photovoltaic/thermal (PV/T) systems, particularly in mild climates where freezing is not an issue. It is efficient at absorbing and transferring heat. Water has a high heat capacity, is non-toxic, inexpensive, and circulates easily. However, it can freeze in cold climates unless treated and, without additives, may cause corrosion.

                Water-glycol mixtures (antifreeze), are composed of ethylene glycol or propylene glycol mixed with water. These are used in colder climates to prevent freezing. They offer protection against both freezing and overheating, and they help reduce corrosion in pipes. However, water-glycol mixtures have slightly lower heat transfer efficiency than pure water, are more expensive, and may pose a toxicity risk.^[1]

                Dielectric fluids are non-conductive coolants that are used primarily in electrically sensitive or high-voltage applications. These fluids are often found in advanced or industrial systems. Dielectric fluids are electrically safe and can handle higher temperatures. However, they are expensive and generally limited to specialized applications.

                Both water-glycol mixtures and dielectric fluids are engineered for efficient heat transfer, electrical insulation, and chemical stability.

COOLANT TESTING

Coolants used in solar panel systems—including water and specialized coolants--require regular analysis for the following properties:

• Thermal Stability: Coolants degrade over time due to heat cycles, UV exposure, oxidation, and contaminants. Testing ensures the fluid performs within spec in terms of boiling point, viscosity, and thermal conductivity
• Chemical Composition: A panel of tests checks for molecular breakdown, loss of fluorinated compounds, presence of impurities or moisture, etc. This helps prevent corrosion of internal components, loss of dielectric performance, and reduced cooling efficiency.
• Dielectric Strength: If the coolant is used in a direct-contact or immersive electrical cooling situation, testing ensures the fluid stays non-conductive. Contamination or water ingress can cause damaging and dangerous shorts and, in the extreme, system failure.
• Corrosion & pH: Water-glycol coolants must be tested for pH changes, corrosive ions such chloride and sulfate, and inhibitor depletion. Poor chemical balance can lead to pipe/system corrosion, pump damage, and reduced life span.

Recommended lab tests include:

• FTIR spectroscopy: to detect chemical degradation
• Viscosity: to ensure flow and heat transfer properties
• pH and Titration: to monitor glycol-based systems
• Dielectric Strength: to ensure electrical safety
• ICP-MS or Ion Chromatography: to check for metal or ionic contamination

                Testing by an accredited lab is strongly recommended for all solar installation coolants. Even plain water coolant, while it may seem straightforward, can cause significant long-term issues without monitoring, such as corrosion, scale buildup, microbial growth, and freezing risk. Neglected testing can lead to: efficiency loss, system corrosion, electrical hazards, costly repairs and/or replacements.

                For more information on working with Eurofins TestOil for solar installation coolant analysis, fill out the form below; visit https://testoil.com/company/contact-us/; call 216-251-2510; or email sales@testoil.com.

About Eurofins TestOil

With more than 30 years of experience in the oil analysis industry, Eurofins TestOil focuses exclusively on assisting industrial facilities with reducing maintenance costs and avoiding unexpected downtime through oil and fuel analysis program implementation. As industry experts in diagnosing oil-related issues in equipment such as turbines, hydraulics, gearboxes, pumps, compressors and diesel generators, Eurofins TestOil provides customers with same-day turnaround on routine oil analysis testing.  For more information on partnering with Eurofins TestOil on oil analysis programs or training opportunities visit https://testoil.com. Contact: Al Yates 216-251-2510; sales@testoil.com. 

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[1] Ethylene glycol is toxic, while propylene glycol is less so.