Site Requirements

Wemyss Renewables work to create bespoke mini hydroelectric schemes providing significant benefits to landowners and land managers, with minimum impact on land use.

Our portfolio of projects continues to expand, and we are actively seeking further watercourses for suitable development.

Successful projects will have a favourable combination of several factors, identified below.  If you have a watercourse with potential for hydroelectric generation, and are seeking a developer or partner to install and operate a scheme on your land, please contact us to discuss in more detail.


The potential scale of a project, measured in Kilowatts.

The rated power of a hydroelectric scheme is determined by a combination of the head and flow.

A rough calculation for determining the likely potential power for a site is as follows:

Power = 7 x Head (m) x Flow (m3/s)

Wemyss Renewables develop schemes over 100kW in size.  However, we would be happy to discuss options for development of clusters of smaller sized schemes. 


The drop between an intake and turbine location, measured in metres.

The head, combined with the flow of water, in a hydroelectric scheme provides the force with which to turn the turbine and generate electricity.  The higher the head, the more force and therefore the more power. 

Hydroelectric schemes can be successful with a low head (2-20m) medium head (20-100m) or high head (100m +), depending on the level of flow through the scheme.

Wemyss Renewables prefer high head schemes, however where there is sufficient flow of water we would be happy to investigate development of low head schemes.

Flow Rate

The amount of water flowing through a watercourse, measured in m3 per second.  A healthy flow of water is essential for the production of energy.

A certain amount of flow remains in the water course as a ‘compensation flow’, and this amount is dependent on the water course.  The water available for use in a scheme, combined with the head, produces the power output for a scheme.  The more water available to run through a scheme the more power will be produced. 

Every water course has not only a different flow rate, but also a different consistency of water levels.  Where river levels fluctuate dramatically and often, it can be more difficult to install turbines to harness the full potential of the scheme.

Wemyss Renewables prefer sites with consistently high flow rates as this provides increased potential for higher power output, although smaller watercourses with a high head can provide very successful schemes.

Grid Connection

The link between the turbine and the national grid network.  This connection is essential to export and sell energy.

The distance to a grid connection point, along with the capacity within the local grid infrastructure, can have a dramatic effect on the financial viability of a scheme.  The higher the potential power output from a scheme the more likely it is that large installation costs can be overcome.

Wemyss Renewables prefer to see locations where turbines can be situated close to existing grid infrastructure to reduce capital costs.  In most circumstances a three-phase supply is necessary for connection.

Site Designations

Environmental or planning designations placed on a site that may require specific attention.

Many areas in Scotland fall under a designation of one kind or another which can put environmental constraints on sites and occasionally restrict power output.

At Wemyss Renewables we work to ensure that schemes do not have a lasting negative impact on either flora or fauna.  We work closely with the Scottish Environmental Protection Agency from the outset to ensure minimal impact on the environment.

Examples of designations that will affect the planning and design process include:            

Sites of Special Scientific Interest
National Parks
Ancient Woodland
National Scenic Areas
Special Areas of Conservation
RAMSAR sites

Wemyss Renewables prefer sites with no designations where possible as this helps to reduce the time and financial cost of obtaining consents and planning permissions.  However, we appreciate that many favourable sites do have designations attached to them, and can work to ensure the best possible outcomes for all parties.

Additional Factors

In addition to the major considerations when investigating schemes, there are many other factors to be considered.

For example, the distance from main access tracks; the existence of bedrock when burying penstock; the ability to route a penstock through a gorge or alongside a steep drop; the visual impact; the proximity to necessary construction materials; the presence of migratory fish etc.

Each site must be considered on a case by case basis.  At Wemyss Renewables we are practiced in identifying potential issues in advance and preparing for these at the feasibility and design stage.