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The Solar Series... Eight applicable surveys from SUMO

Updated: Apr 10

Solar Energy remains a hot topic and SUMO have eight applicable surveys from Design, to Construction, and Monitoring of your Solar Scheme.

With over 1000 Solar Farms already operating in the UK and the Solar Market projected to triple in the next 5-10 years to meet the Government's commitment to reach net zero by 2050, there are 2000+ potential solar sites to investigate across the UK. Whether these sites are 1ha or 1000ha, SUMO has a bespoke suite of services to assist with planning, risk mitigation, detailed design and construction of your solar farm.


Step 1: Topographic Survey

Combining traditional topographic surveys with UAS (drone) topography to produce drawings and 3D Outputs, this collaborative approach allows for large landscapes to be survey much more efficiently.

This traditional terrestrial survey will provide a full and comprehensive topographic survey, where our surveyors aim to map all accessible features visible above ground. This includes basic site features such as existing buildings, walls, fences, surface changes, vegetation, tree positions and utility service covers. We will also survey ground levels at a nominal interval (typically 5 – 20m depending on the requirements of the site), as well as any significant changes in ground levels, such as banking or slopes, to produce a comprehensive ground profile.

Above -  A traditional Topographic Survey of a large Solar Farm.

Step 2: Photogrammetry Survey

As well as capturing topographic data (Step 1), UAS photogrammetry can also produce highly accurate Digital Elevation Models (DEMs) and orthorectified mapping of large areas. This output is equivalent to LiDAR with the added benefit of increased resolution at 1 - 5cm, where existing LiDAR is typically 1m to 2m, or 25cm at best (when available). Textured Digital Elevation models, like the example below, can help to understand and visualise the landscape, thus aiding the design process of the solar farm layout. This is also a complementary technique to Step 3: Geophysical Survey.

Above -Digital Elevation Models (DEMs) identifying the profile of the land, plus archaeological features hidden beneath the modern landscapes.


Step 3: Geophysical Survey

As most solar farms are in rural locations, there is often a need to address the issue of potential archaeology on site and Geophysical Surveys can provide a rapid, cost-effective method of evaluating archaeological remains without excavation.  The typical targets found are settlement sites and ditches; pits, post holes, field systems and enclosures; buried megaliths, plus kilns and industrial sites. However, in many cases the geophysics reveals no archaeology, which may remove the requirement for any intrusive archaeological investigation altogether.

Above -  A plan view of magnetic survey data showing two rectilinear enclosures, of which the southern-most may be a cursus monument.  A north-east / south-west aligned field system has also been identified, along with a post-medieval field boundary, evidence of ploughing and modern underground services. A trenching strategy can now be devised, targeting anomalies in the geophysics.

Step 4: Utility Survey

Whilst an extremely detailed survey is required in city centres, on rural sites we conduct a perimeter survey only, and any services that are located, are traced across the site and their location recorded. This means that you get all the utility information that you need without spending a fortune on a survey which doesn’t give you any more information!

Using the latest detection technology including electro-magnetics, signal induced threading and ground penetrating radar, SUMO can locate metal pipes, plastic pipes, drainage systems, electricity cables, telecoms and fibre optic cables. The survey data references the ordnance survey grid and level datum as standard. The drawing can also be supplied to a specified grid & level datum, as well as the option to overlay it on an existing topographical survey.


Step 5: Electrical Earthing

The design and installation of new solar farms and the associated electrical grid infrastructure, requires a full understanding of a site’s electrical properties in order to design an appropriate earthing system which may include earthing plates, earthing rods, or earthing pits. 

If not earthed correctly, solar panels and other electrical equipment can be damaged by electrical surges, lightning strikes, and other electrical disturbances. Such damage can then reduce the efficiency of the solar panels or wind turbines, and even cause them to fail completely, leading to costly repairs or replacements, impacting upon their operational efficiency.

The electrical properties of a site are measured through soil resistivity testing, which measures the capacity of the ground to pass an electrical current. Testing is best performed to a depth of 50m or more (dependent upon the design needs), to provide the design engineer with an electrical model of the soil and bedrock layering, that can also be correlated with borehole data from the site. As a general rule, lower resistivities make the design and installation of an earthing system simpler.

Above : Soil resistivity testing in progress on a new solar farm development.


Step 6: Soil Thermal Resistivity

Prior to the design and installation of underground electrical cables, it is important to understand the thermal properties of the in-situ soil or made ground, to ensure the heat produced by current flowing through an underground power cable is properly dissipated and avoid premature failures.


Soil thermal resistivity testing measures the capacity of the ground to conduct or dissipate heat and the thermal resistivity of the soil will determine whether a buried power cable remains stable or overheats.  A build-up of heat around the cable can reduce transmission efficiency, or in the worst cases cause it to melt. 


Often estimations are made, but where conditions are uncertain or variable along a cable route, it is important that a proper quantitative assessment is made of the ground.

Above - In-situ thermal resistivity testing with a needle probe.


The testing procedure involves taking measurements along the cable route at intermediate or transitional locations. A needle probe is inserted in a pit or an open trench at the proposed cable depth. Thermal resistivity and conductivity readings can then be recorded and presented in a tabulated format to be used for accurate calculations by the installation engineers, prior to determining the capacity of the cable to be laid and the required sub-structure.

Step 7: Setting Out

Using the client supplied design plan, we can set out the entire site, including the solar panel pile positions, identifying exactly where they need to be located.

Above – A plan of a solar farm for setting out.


Step 8: Thermal Monitoring

For established solar farms, SUMO can collect regular thermographic data, for analysis by solar farm monitoring companies, who can identify the effectiveness of the individual panels and locate any faulty ones, maintaining the Solar Scheme’s efficiency.

When solar panels malfunction, it can mean a loss of efficiency and reduced energy production. Thermal imaging can detect heat signatures that may be indicative of defective solar cells. From a small group of panels on residential houses to a large solar farm, a UAS thermographic survey offers the most rapid and cost-effective solution to identifying panel defects and mitigate energy loss, whilst ensuring your investment is functioning at its highest level.

Above – A thermal survey collected by UAS, showing a fault in one of the solar panels.


Following all of these 8 steps will help you to meet your planning requirements, mitigate your risk and create the best and most cost-effective design for your site.
Finally, don’t forget that SUMO can supply each these services independently, or as part of a bespoke package to meet your needs.

We are here to offer advice and solutions, not just a survey: so, if in doubt, pick up the phone and speak to us!

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