Commercial solar PV installer in the UK

Site assessment

The site assessment for the intended Solar PV power plant would involve an investigation into a range of technical and infrastructural issues with land requirement. The following is the basis for a first checklist.

1. Solar resource at the site

• Annual irradiation (kWh/m²)
• Seasonal fluctuations
• Share of direct and diffuse irradiation
• Shade analysis

2. Site issues 

• Dimensions of area available
• Actual land ownership
• Options for enlarging the installation at a later date, e.g. via the use of neighbouring lots of land
• Building restrictions (e.g. due to the site being in a nature reserve)
• Ground/soil characteristics (if known). 

3. Topography

• Flat surface or sloped
• Orientation of slope (per sub-area); a south-oriented slope optimises land use by reducing the distance required between PV arrays

4. Infrastructure

• Road access
• Power grid 
• Distance to the grid-connection point (medium voltage)
• Capacity and maximum power carrying capacity at that point
• Technical availability of the grid
• Access to telecommunication
• Distance to cable or wireless network
• Available bandwidth
• Technical availability of telecommunication services
• Operational aspects
• Need for maintenance, e.g. cleaning of the modules due to dust, soot, etc.
• Prerequisites for the modules’ orientation due to the type of power production planned (straightforward feed-in to the grid, feed-in to the grid considering time-of-day tariffs, self-supply for a large consumer, etc.) 
• If applicable, power production requirements and regulations
• Minimum/maximum annual amount of electricity generation
• Minimum contribution to supply (quota).  

PV plant layout and system yield

In order to do a first estimate of the potential yield (electricity production) of the envisioned PV power plant, an initial layout design would be done. This involves deciding on the number of PV arrays, their location, their orientation, etc. Sufficient distance between the PV arrays is required to avoid or minimise shading.

1. Logistics

• Storage facilities during construction and assembly
• Assembly of module mounting structures/racks
• Fixing of modules
• Access for maintenance

2. Inverter(s) and transformer(s)

• Installation and access
• Shading caused by inverter housing

3. Shading from adjacent land

• Shading caused by trees and vegetation on neighbouring parcels of land
• Shading caused by adjacent hillsides
• On the basis of the layout design and the details of the PV modules to be used, the PV nominal power can be determined, and based on that information the total annual yield can be estimated using simulation tools such as PV*Sol or PV-Syst5.
• Different designs (with different layouts and different modules) would be tried out, and their annual yields simulated, or their ability to meet specific supply requirements (e.g. meet required daily power curves).
• The main design parameters are:
• Distance between module mounting structures/racks
• Tilting angle of module mounting structures/racks
• Orientation of module mounting structures/racks
• Type of modules
• Type of inverters.
• Both the total annual electricity generation and hourly supply curves can be produced. These would form the basis for estimating future predicted revenues from power production in the case of grid feed-in.

On the basis of the initial Solar PV plant design(s), estimates of equipment requirements can be made for the following:

• PV modules
• Mounting frames and structures
• Cabling
• Inverter(s)
• Transformer(s)
• Other accessories.

Furthermore, a first evaluation of the amount of work for assembly, excavation of cable trenches and possible road works can be carried out. Besides the investment in equipment, other costs also need to be estimated, such as:

• Planning and project management
• Licenses and approvals
• Building permit fees
• Grid-connection costs.

If the result of the feasibility study is positive, a decision to begin a PV project will be made. This decision would be followed by a careful project planning procedure to include – but is not limited to – formal planning aspects (applications for permits, etc.), detailed implementation planning, and logistics planning for construction and assembly. Grid infrastructure and electricity market requirements will provide the framework in which implementation planning takes place.

Project stages: EPC, Commissioning, and operations

The following are the key stages of planning, construction, and operation of the Solar PV power plant:

1. Yield assessment

a. Solar radiation data sources

b. Landscape topology assessment

c. ‘Technical availability’ of PV systems

d. Yield assessment and project bankability

2. Legal and regulatory issues

a. Permits and licenses

b. Access to the grid

c. Access to the electricity market

3. Infrastructure

a. Grid access and availability

b. Standards for cables and metering

c. PV plant telecommunication systems

d. Logistics and site-protection measures

e. Availability of technical support

This includes a well-managed schedule for the delivery and the provision of sufficient storage facilities/space for key components. Comprehensive plans would include construction diagrams, mechanical diagrams, cabling and wiring diagrams.

This stage includes keeping contact with the local authorities and communities in order to ensure the project’s acceptance by local residents. The acceptance by local residents would help to avoid issues with the local residents or planning permits. 

Construction and installation planning

• PV mounting structures, cables, and cable routes: Alongside the PV modules and inverters, the mounting structures/frames/racks/mounts (terminology differs) and cables are key system components.
• Cable trenches: Irrespective of the inverter concept chosen, numerous long cable routes are required on the PV park. The cable routes would be short as possible in order to reduce cable losses.
• Mounting structures/frames racks (installation): Usually, the supporting posts for mounting structures would be rammed into the soil. But if the soil is stony or soft, foundations may be required. If ground stability cannot be ensured, we would seek the advice of a soil expert