This guide lists the investigations that an owner should complete, or at least scope, before giving notice to proceed to an EPC contractor. They cost a small share of the project and avoid some of the largest risks.
Why investigate before notice to proceed
An EPC contract transfers risk from the owner to the contractor, but only for the risks that are defined in the contract. Unknown ground conditions, grid constraints or access limits are commonly kept with the owner or priced with large contingencies. Studying them before signature narrows both.
Our overview of EPC for renewable energy projects sets out how risk is divided, and the feasibility study guide covers the earlier decisions.
Topographic and boundary survey
An accurate survey of land boundaries, levels, existing structures, drainage lines and utilities is the base for layout and earthworks quantities. Aerial surveys with drones are fast and cheap for large sites and give detailed contours.
Check the legal boundary with a licensed surveyor and confirm rights of way, easements and any exclusion zones. An array laid out across a boundary is an expensive mistake.
Geotechnical investigation
Boreholes, trial pits and tests of soil resistance, pile load tests and corrosion potential show how the ground will carry foundations. For solar, driven piles are common, and pull-out and lateral tests show whether they will work in the soil or whether other foundations are needed.
Investigate thermal resistivity of the soil for cable design, and groundwater level. Underestimating rock or cobbles can bring heavy cost and delay.
Resource assessment
Solar projects need measured or modelled irradiance data, and wind projects need measured wind speeds at hub height, often over a year. Use data from reliable sources and consider onsite measurement for large or complex sites.
The resource assessment feeds the energy yield forecast used by lenders and offtakers. Treat it as a bankability item.
Grid connection studies
Confirm the connection point, voltage, capacity and the requirements of the grid operator. Grid studies may show that reinforcement is needed, that curtailment is likely or that the protection and control requirements are strict.
The connection timetable often decides the project schedule. Get written confirmation from the operator and understand any conditions.
Environmental and social assessments
Environmental studies cover habitats, birds, water, noise, visual impact and cultural heritage. Social studies cover land use, community effects and employment. Permits often depend on them, and lenders follow international standards for larger projects.
Do not leave these to the end. Findings can change layout, exclusion areas and construction timing.
Hydrology and flooding
Study rainfall, runoff, flood levels and drainage. Arrays and substations in flood paths need design measures, and even a modest drainage change can alter earthworks and civil costs.
Check for seasonal changes in access routes, since roads that are fine in the dry season may be impassable in the wet season.
Access, logistics and construction constraints
Survey the route for delivery of heavy equipment such as transformers, cranes and piling rigs. Check bridges, road widths, turning radii, power lines and local rules for abnormal loads. Identify where materials will be stored and where crews will live.
Consider local labour, security and transport conditions. These have a direct effect on construction cost and schedule.
What goes wrong when studies are skipped
Typical outcomes include piles refused by rock found after contract signature, a flooded access road during the wet season, a grid operator announcing curtailment limits after financial close and an environmental condition that moves the array boundary. Each leads to claims, extra cost and delay.
The studies in this guide are the cheapest insurance available against these events.
Budgeting and scheduling the investigations
Studies typically take weeks to months, and some, such as bird surveys or wind measurement campaigns, depend on the season. Include them in the development schedule, and start the longest ones first. Budget a small share of the project cost, and keep a contingency for follow-up work.
Appoint a single coordinator who tracks reports, flags findings that affect design and passes them to the EPC bidders in a consistent format.
Sharing results with bidders
Give all bidders the same data, and the same statement of what they may rely on. State clearly which reports are for information and which are contractual baselines. Allow bidders to visit the site and ask questions in a structured period.
Equal information produces comparable bids, and it reduces the chance of claims after award.
Using the studies to set the schedule
Place study results on the project schedule as gates. For example, the ground report gates foundation design, the grid study gates the electrical design and the environmental baseline gates permit submission. A gate that is missed moves the dependent work, and the schedule shows it.
Review gates monthly with the EPC team so that findings flow quickly into design.
A short pre-NTP checklist
Before notice to proceed, confirm that the boundary survey is signed off, the ground report is issued to bidders, the resource data is bankable, the grid agreement is in writing, the main permits are in hand or have a clear path and the access route has been driven by the construction team.
Any item that cannot be ticked should carry a named owner, a date and an agreed contract treatment.
Turning findings into contract terms
Share the investigation reports with bidders, and state which parts the contractor may rely on. Define a clear mechanism for unforeseen ground conditions, such as a price adjustment based on tested ranges.
Link payments and risks to defined events, and see the payment milestones guide for ways to do so.
Who writes this
Early site studies shape every renewable contract that our EPC engineers price. Notes from the USP&E EPC team. Rather than brokering, USP&E takes responsibility for EPC and O&M delivery; its background is 24+ years in the field, 150+ power projects in 45+ countries, 25,000 MW contracted since 2002. See our hybrid power systems work, where early investigations decide the design.
Offices: Colorado Springs (1755 Telstar Dr, Suite 300), Knoxville (800 S Gay St, Suite 700), London (162-168 Regent Street), Johannesburg (22 Kildoon Rd, Bryanston), Cape Town (31 Brickfield Road, Woodstock) and China (No. 1 Ningzhou Road, Wuxi). Regions: USA | AFRICA | UK | UAE | CHINA. ISO 9001 and ISO 45001 certified.
Questions about pre-construction investigations
Who pays for site investigations?
Usually the owner, before notice to proceed, though some contracts share the scope. The cost is small compared with the risk it removes.
Which study carries the most risk if skipped?
Geotechnical and grid studies, because they affect foundations, cost and the connection date.
Can the EPC contractor carry unknown ground risk?
Only if the contract says so, and then the price will include a contingency. Defined ranges and adjustment rules are fairer.
How early should grid studies start?
As early as possible, because connection timetables often set the project schedule.
Preparing a renewable project for EPC?
Send us the site, capacity and connection details, and our engineers will list the investigations to complete before notice to proceed.
Phone +27 10 822 2324, email info@uspeglobal.com with your site data, or go through the project enquiry form. Generation equipment for hybrid projects is listed in the USP&E inventory.