Solar Farm Grounds Management Vegetation Control

United Utilities Renewable Energy (UURE) owns and operates upwards of 60 renewable technology assets across the North West of England, including solar photovoltaic, hydro and wind turbines. Many of the solar photovoltaic (PV) systems are mounted on the ground, meaning management of nearby organic growth is an important part of the overall Operations & Maintenance strategy and is key to ensuring the safe and efficient on-going output of the system.

Opportunity

Challenge opens

23/05/2019

Challenge closes

02/08/2019

Benefit

United Utilities Renewable Energy (UURE) owns and operates upwards of 60 renewable technology assets across the North West of England, including solar photovoltaic, hydro and wind turbines. Many of the solar photovoltaic (PV) systems are mounted on the ground, meaning management of nearby organic growth is an important part of the overall Operations & Maintenance strategy and is key to ensuring the safe and efficient on-going output of the system.

Some sites are non-traditional in the way that the modules (solar panels) are mounted i.e. they are in very close proximity to the ground. This means that organic growth, including grass, weeds, invasive species and even small trees can pose a significant problem by growing around and overshadowing the panels.

Images above - Prescot array hidden by vegetation growth

The issues often created by this include:

1). An impact on performance

2). A number of potential safety implications

3). An increased need for panel cleaning

4). A detrimental aesthetic effect.

Due to the nature of some sites, use of herbicide chemicals is currently prohibited as this has the potential to contaminate water supply, as does grazing of livestock. There are also weight restrictions limiting the use of heavy machinery.

Performance

Solar photovoltaic systems depend upon light which is converted into DC power and then eventually into AC power which can be utilised by most site processes, helping to lessen reliance on grid provided electricity and assist in reduction of energy costs.

When the modules are shaded by long grass etc. the performance is significantly reduced (up to 40%) and therefore the output of the overall system decreases resulting in a loss of revenue. Significant shading can also reduce the lifespan of the components, meaning Totex (Total Expenditure) costs increase when taking into account cost vs benefit analysis i.e. spending maintenance budget to maximise the efficiency of output from the system in terms of monetary value and/or electrical generation. Shading can create a whole host of issues, including long-term reduction in output capabilities and a lengthened investment ‘payback’ period for the photovoltaic system as a whole.

Safety

Modules that are subject to significant organic growth from beneath and also directly adjacent can represent safety hazards due to heat build-up, which can eventually result in a fire. Modules should be kept as clear of debris as possible in order to minimise this risk and ensure continued airflow for cooling purposes.

Warm and dry periods of weather are particularly problematic, as this can result in large swathes of grass growth dying back and becoming dehydrated, which forms sometimes tinder-dry piles of material which can easily ignite if there was an electrical fault in the panel or associated wiring. Solar PV modules are always live and producing power whilst there are sufficient light levels and it is practically impossible to isolate a full system.

Aesthetics

UURE as an organisation has expended a significant amount of investment capital into the renewable assets it currently owns; it makes sense that the sites and associated equipment are maintained in a way that makes them presentable and portrays the technologies involved in a positive manner. UURE strives to display the best possible site standards and areas that are difficult or dangerous to maintain can have a detrimental effect on these standards.

Problems

As stated previously, herbicide chemicals are currently prohibited on most clean water sites due to the risk of contamination, meaning the PV systems cannot be treated using traditional methods of weed suppression etc. Only where specific approval has been granted by Water Quality Board (WQB) can these chemicals be used; a fully developed proposal needs to be presented to WQB who can then technically risk assess the methodology put forward before making a decision on whether it can proceed or not.

Due to the nature of the equipment, there is a risk associated with using cutting equipment (such as strimmers) within the vicinity of the modules, as this could result in damage to the equipment, cables and possibly result in electric shock / electrocution.

Furthermore due to the lower than standard ground-mounting of some sites, consideration needs to be taken around concrete mounting blocks, steelwork etc. There is a need for any solution to be able to work around these obstacles

A number of different methodologies have been used previously to try and reduce organic growth and increase weed suppression, including the installation of geotextile membranes, washed gravel, Lytag etc. but this has proved relatively unsuccessful and the sites still require a significant amount of physical removal of nuisance growth.

It is anticipated that innovation solutions would come from, but are not limited to, the following areas:

  • Civil engineering industries
  • Agriculture / horticulture
  • Environmentally friendly / natural weed suppression technologies
  • Grounds maintenance equipment technologies
  • Drone/Robotics/AI/ visualisation

The solution should be fully compliant with CDM Regulations 2015 and Health & Safety At Work etc. Act 1974 (including relevant regulations included within the ‘umbrella’ suite of legislation).

Additional Details

The selected competition winner will focus first on a trial 2.7MW site that has the most challenging vegetation growth resulting in significantly reduced solar energy generation.

There are approximately 11,000 panels on the site, in 4 arrays.

The dimensions of the site are approximately 200m x 300m

Rewards and benefits

Successful applicants will be given an opportunity to pitch to the Challenger. The package may also include:

  • Support from the Knowledge Transfer Network or the Energy Systems Catapult
  • Support in the development of a prototype or pilot
  • Technical support
  • A place in KTN or ES Catapult events
  • A potential business collaboration
  • Investor introductions (if investment is required)
  • Potential to lead to further collaboration in joint funding bids.

Solution Requirements

Functional Requirements

  • Provide a system/solution that; (a) limits organic growth, (b) effectively reduces/removes organic growth upon application/use, or (c) both functions

Technical Characteristics

  • Must meet Water Quality Board approval for use on clean water facilities

Operating Conditions

  • Wastewater facilities
  • Clean water facilities
  • Green field sites

Deployment Timescale

  • Launch of the Competition: May 2019
  • Deadline for applications: August 2019
  • Selection and notification of finalists: TBC
  • Solutions should be fully deployable for prototype testing within 3 months of competition win.
  • Full commercial deployment within 3 months (there are operational sites that a solution could start work on immediately if the system is already commercially available).

Cost requirement and market opportunity

  • There are 19 sites to which the winning solution could potentially be applied
  • The cost of the system must be less than the cost of strimming contractor (circa £50k) or outweigh the cost of buying electricity when the system isn’t operating at optimum capacity. These costs currently amount to several tens of thousands of pounds per site per annum

Eligibility and assessment criteria

  1. Entrants to this competition must be: 
  • Established businesses, startups, SMEs or individual entrepreneurs. 
  • UK based or have the intention to set up a UK base.

2. Applications will be assessed on: 

  • Relevance to the topic, innovative nature of the subject, coherence of the proposed business model
    • Feasibility/ economic viability
    • Development potential
    • Maturity of project/solution
    • Ability to launch project quickly/Ease of implementation
    • Price/quality ratio
    • Suitability for the UK and European Market

    IP and Potential Commercial Route

    • Existing background IP associated with a potential solution will remain with Solution Provider(s). Where any new IP generation is envisaged, it will be subject to the mutual IP agreement of the Solution Provider(s) and Innovation Challenger.
    • Any commercial deployment of transferred solution or newly developed solution, through licensing, joint venture, partnership or direct investment, will be subject to the commercial agreement between the Solution Provider(s) and Innovation Challenger.
    • Where necessary, a non-disclosure agreement (NDA) may be signed to uphold confidentiality in the engagement between the Solution Provider(s) and Innovation Challenger.
    • Innovate UK and KTN do not take any share of IP ownership or enter into commercial venture through the EnSiX programme.

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