The design of solar-powered surveillance and telecommunications systems requires a meticulous approach to ensure safety, reliability, and efficiency. Too often now I see systems deployed with little regard for the above. This ultimately leads to a poor client experience and potentially unsafe conditions when clearly price has been the main consideration. This article explores the essential factors in design risk assessment, emphasising site selection, power system design, structural integrity and operational safety.
Site Selection and Environmental Considerations
No set of site conditions or client requirements are ever exactly the same, so rarely can an assessment be based on a ‘one size fits all’ approach, nor should it be. The following are just a few basic points that should always be considered before any system is selected as suitable for a deployment:
Solar Irradiance: Evaluating the site for optimal solar exposure is crucial. Ensure the location receives sufficient sunlight throughout the year to maintain consistent power levels. This assessment helps in choosing the right site that maximizes solar energy capture.
Weather Conditions: Assess the frequency and severity of adverse weather conditions, including storms, snow, and heavy rains. These factors can significantly impact the platform's performance and must be considered to ensure the system's resilience and reliability.
Ground Conditions: Ingress and Egress of equipment must be taken into account as the seasons often dictate the suitability of a deployment, bad weather or simply winter will influence any deployment or collection, but also just the nature of ever evolving sites can hamper access to equipment even whilst it’s in use.
Orientation and Obstacles: Shading has a significant effect on a systems ability to function properly, any deployment location should be surveyed to assess not only its current conditions but also those of the contract ongoing. Highways can be a particular problem when considering shading as vegetation is rarely managed and quickly grows to obscure panels. Obstacles such as signs and especially crash barriers also have a hugely detrimental effect on solar harvest, the very worst cases we’ve all seen being towers installed under trees, facing north.
Power System Design
Energy Storage: A robust energy storage system is necessary to provide power during periods of low sunlight. Consider the type, capacity, and lifecycle of batteries to ensure a reliable and long-lasting energy supply. Batteries systems should ideally be designed not only to power the equipment but also to protect the batteries themselves from frequent deep discharge. If batteries are constantly being taken to their limits it doesn’t take long for them to degrade to a state that requires them being completely replaced, not only is this a costly exercise it also has a negative effect on any perceived carbon savings and whilst this isn’t necessarily the main consideration for using solar in the first place considering any environmental impact should still be part of any assessment.
Power Management: Power management systems to optimise energy consumption help extend the operational life of the platform by efficiently managing power distribution and usage. Proper management and systems catered to the clients specific needs, reduce downtime and therefore engineer visits, which adds to the overall safety of a system, especially when deployed in a location such as Rail or Highways where access can be limited. The absolute last resort should be having to swap out batteries due to a lack of power especially in the environments above, the duration of these works along with the manual handing involved can only ever be considered high risk.
Solar Capture: Studies should be undertaken for every project to ensure that a system has enough potential power harvest to satisfy both the above points for the duration of any contract and not just the months of increased irradiance, this ensures a good client experience and helps to bolster the industry’s image, whereas systems that are underpowered will only result in downtime damaging the perception of solar security systems and at times causing dangerous situations.
Structural Integrity and Durability
Materials: The use of corrosion-resistant and durable materials to withstand environmental conditions ensures the longevity and reliability of a system, even in harsh conditions. This adds to the overall safety of the product making deployment and removal of systems less problematic, which in turn reduces operatives time on site. The less time spent deploying reduces the overall risk, especially important in Highways applications where ‘time windows’ are limited or more likely works are undertaken at night.
Mounting and Support Structures: Ensure the mounting structures for solar panels and equipment can withstand wind loads, and other mechanical stresses. Robust structural design is critical for preventing damage and maintaining stability.
Maintenance Accessibility: Design the platform for easy access to components for maintenance and repairs. Equipment should be secure to prevent any unauthorised or malicious access, especially electrical systems however these measures shouldn’t hamper an engineer’s ability to carry out maintenance task if and when required
Surveillance and Telecommunication Equipment
Reliability and Redundancy: Select high-reliability components and consider redundancy for critical systems to prevent single points of failure. This enhances the overall resilience of the system.
Data Security: Implement robust cybersecurity measures to protect against unauthorised access and data breaches. Ensuring data integrity and security is paramount for surveillance systems.
Signal Interference: Assess potential sources of signal interference and plan the placement of antennas and sensors accordingly. This ensures clear and uninterrupted communication. EMC testing of equipment can form a large part of any design risk assessment but especially in Rail applications where spurious radio emissions are heavily scrutinised to mitigate risk to operations and rolling stock
Safety and Compliance
Electrical Safety: Design for safe electrical operation, including proper insulation and grounding, prevents electrical hazards and ensures safe operation. Proper design should always be undertaken to ensure correct cable selection along with appropriately rated terminations, as the vast majority of Solar surveillance systems are running as DC. Battery systems especially contain a large amount of current, even if equipment is only using a very small amount of it in normal use, this needs to be accounted for, correctly harnessed and fused. DC runs hot and poor or undersized terminations can lead to fires and the danger of this is only heightened when we consider that should any fire occur, it will most likely be in an enclosure containing the batteries themselves.
Regulatory Compliance: Ensure the design complies with any local and international regulations and standards for both telecommunications and solar power systems. Compliance with regulations ensures the legality and safety of the installation but more importantly ensures the safety of operatives and end users. The industry needs to set these standards and as it’s still in its infancy but growing fast, all manufacturers have the opportunity to set the bar high and not simply create a race to the bottom in favour of cheaper systems and inappropriate deployments.
Hazard Mitigation: Identify and mitigate potential hazards such as fire risk from batteries or electrical faults, and physical security threats. Batteries in enclosed spaces pose a real risk if not properly selected. Sealed AGM and most Lithium batteries can be operated safely in properly sized enclosures, however flooded cells should not be used without proper consideration due to their natural gassing of Hydrogen during charging. It is of course possible to design out this issue with ventilation, but this needs to be carefully calculated to ensure there can be no build-up of dangerous gas, or at least not in any significant concentration. A design risk then needs to account for environmental conditions as any venting changes the IP rating of the equipment and very often the IP integrity of the enclosure itself is paramount, especially in Oil and Gas applications.
Operational Monitoring and Control
Remote Monitoring: Integrate remote monitoring systems to continuously track performance, detect anomalies, and facilitate remote troubleshooting. This enables proactive maintenance and issue resolution.
Autonomous Operation: Incorporate autonomous or semi-autonomous control systems to manage power distribution, system diagnostics, and fault recovery without human intervention. Consider the addition of remote reset devices as due to the nature of certain equipment manual intervention is sometimes required but access can be limited, this enhances operational efficiency and safety.
Electrical Safety
Overcurrent Protection: Ensure proper overcurrent protection devices (fuses, circuit breakers) are in place to prevent electrical fires or damage due to short circuits. These should be selected and rated ideally in line with BS. 7671 or cable manufacturers instruction, always taking into consideration that their typical use is in DC systems so their suitability should be confirmed for this application.
Insulation and Grounding: Ensure all electrical connections are properly insulated and adequately grounded to prevent electrical shock hazards. Most solar surveillance systems are mobile and typically use a chassis ground, especially in Extra Low Voltage (ELV) equipment. However, when 230V is present in an enclosure, special attention must be given to the adequacy of the earthing.
Bonding: Designers and specifiers should also take into account any special circumstances that may require a tower to have an enhanced level of protection, both for the equipment itself but also other systems in the vicinity. A good example being a towers proximity to a building or structure, having an LPS (lightning protection system) if this is the case, then a risk assessment must be carried out as to the towers potential to negatively influence that buildings integrity.
Containment: All cables within or outside an enclosure should be contained or secured by a suitable means, especially those carrying electrical current. This not only protects the cables themselves but also reduces risks to operatives by limiting the risk of electric shock and removing unnecessary trip hazards or situations where they may become entangled. Even in ELV systems where voltages are low there is a serious risk of burns should s person come into direct contact with a damaged DC cable and the last thing we should see is PV cables draped along the floor when arrays are installed remote to the cabinet. Even cables travelling up masts should be retained in some way, whilst they usually don’t carry any real risk of shock just the fact that they are flapping around can ruin the whole perception of the industry.
Battery Safety
Battery Enclosure: Use robust and weatherproof enclosures for batteries to prevent exposure to the elements and mitigate risks of overheating or freezing of cells.
Battery Chemistry: Select safer battery chemistries such as Lithium Iron Phosphate or Sealed AGM Lead acid, the latter being spill proof and neither being able to vent dangerous gases whilst charging and discharging. Typically Lead acid is selected due to its wider temperature operating range, with the majority of Lithium batteries being hampered by extremes of temperature however this technology is always improving.
Battery replacement: Lift and shift is another article on its own but due to the heavy nature of most batteries and especially Lead, any system should be designed to allow safe replacement. Manual handling is nearly always required to carry out a battery swap and often under difficult site conditions, this operation must be assessed prior to any deployment to ensure the works are as safe as possible.
Structural and Installation Safety
Height and Access: Plan for safe installation and maintenance access, wherever possible working at heights should be designed out of any system however when required ensure that safe access buy means of a scaffold or MEWP is feasible.
Fastening Points: Use secure and durable fastening points for mounting all equipment to prevent detachment during adverse weather conditions.
Tower lockout: Many telescopic towers rely on a single wire rope and a fixed point for erection but often this means that there’s no viable method to secure it, should the rope be damaged or even cut this can lead to a highly dangerous situation. Multiple locking or safety features should be included in any design to act as a failsafe and moving parts such as winches, pulleys and the wire ropes themselves should be enclosed to prevent accidents.
Any design risk assessment should take into account all of the points I’ve listed but even this list is not exhaustive and very often a site will present a whole new set of potential problems. As I stated earlier a ‘one size fits all’ approach should never be applied to any risk assessment and when designing a system, all deployment situations should be judged on their own merits. This can only lead to improved client experiences helping to ensure the industry continues to grow whilst maintaining safety for all involved.
