The Hydro and Wind Company Securing a clean energy future, profitably

Wind Site Self Assessment (WSSA)

This Wind Site Self Assessment (WSSA) tool is the first stage of our modular Windpower Feasibility Study. The tool will guide you through the initial steps necessary in order to check the viability of your site for a wind turbine project.

The process takes about 20 minutes and consists of 11 steps in total that appear as you answer each question. If an answer you give suggests that the site is unsuitable, the form will terminate. This is a simplified initial assessment however, so there may still be options that could make it viable. If the assessment terminates please provide any further information that you think makes the site viable in the box provided.

The initial assessment will be followed up by a brief overview of your site by our experts to assess initial viability for one or more wind turbines, and whether we recommend progression to the next stage in the feasibility process – Scale Assessment. This includes a short discussion about your project goals, site available and key risks.The use of the tool is free, but we charge £50 + VAT for our Expert Overview of the information provided. Upon submission of the WSSA information you will be redirected to our web shop to complete payment of the fee which will initiate our initial expert assessment. You will receive a report and be contacted by one of our experts within 5 working days.

1 Find your property

  • 2 Mark the boundary

    Click the 'Draw Property Boundary' icon above, then repeatedly click the map along your boundary line until you close the loop.

  • 3 Check the wind speed

    Click the 'Check Windspeed' icon. The average windspeed at 45 metres will be shown in an overlay.

    Go to Step 4 below to see whether you have sufficient wind-speed on your site.

Add features to map at relevant question

  • 4 Is your wind speed sufficient?

    A good site for a wind turbine needs exposure to wind. The amount of energy and therefore income generated by a wind turbine, increases disproportionately with increasing wind speed, so more wind is always better. It is good practice to position a wind turbine in the most exposed location, though sometimes exposure to wind is sacrificed a little to make a wind turbine less visible, which can help with obtaining planning permission.

    How does your windspeed compare?

    The table below indicates wind speed compared with commercial-grade wind sites:
    Wind speed (m/s) Comment
    Less than 5 m/s Windspeed less than 5 m/s Too low for a commercially viable project.
    5 – 6 m/s Windspeed 5-6 m/s A bit low for a commercially viable wind turbine, unless you can consume all of the energy on-site to maximise the benefits of offsetting imported electricity.
    6 – 7 m/s Windspeed 5-6 m/s A reasonable site with a reasonable return-on-investment, particularly if the electricity can be used on-site.
    7 – 8 m/s Windspeed 7-7 m/s A good 'commercial grade' wind site that third-party wind investors would be interested in, so would make a very good private investment once planning consent was obtained.
    8+ m/s Windspeed 8+ m/s Exceptionally high wind speed – if you could get planning consent this would be a valuable wind site with a high return-on-investment.

    How accurate is the wind speed estimate?

    The wind speed estimation software is based on the old UK Government NOABL database. Although good for initial estimates, we generally find the average estimation error is +/- 0.5 metres per second (m/s) - but unfortunately it can go either way! Despite this, it is as good a tool as any for having an initial free check.

    A more accurate check is possible using the Met Office’s basic VMM service, though this would normally only be done at a later stage because it costs money. The NOABL tool is based on the average wind speed over a 1 km2 grid square at 45 metre 'hub height'.

    We normally supply turbines with hub heights from 25 metres to 125 metres. For higher hub heights the wind speed will be higher than the estimation tool indicates because wind speed increases with height. If the likely turbine is higher than 45m hub height we will apply a correction factor to the wind speed.

  • 5 Mark desired and existing wind turbines on the map

    Desired turbine location

    Desired turbine location

    If, after consulting the tables above, you consider the wind speed at your site viable for a wind turbine, use the 'Desired turbine location' object to mark the most desirable turbine within your property boundary, i.e. at the best location based on the highest wind speed. If there are multiple locations at high wind speed then choose a location you consider to be suitable.

    Existing turbine location

    Existing turbine location

    Please also mark any existing turbines you are aware of near to your property using the 'Existing Turbine' tool.

  • 6 Mark and measure proximity of nearest properties

    Financially Involved Property

    Financially Involved Property

    Modern wind turbines are incredibly quiet, but even so they are large machines so will produce some noise. The minimum separation distance between a wind turbine and nearby properties depends on whether the properties are 'financially involved' in the wind project or not.

    Non Financially Involved Property

    Non Financially Involved Property

    Financially Involved in this context means the person living in or using the property will get an income from the wind turbine. It's also necessary to consider properties that are not financially involved.

    • Using the relevant markers, mark all financially involved properties on the map.
    • Next repeat the same process for the three nearest non financially involved properties
    • Ruler tool

      Ruler tool

      Using the ruler tool measure the distance between the desired turbine location and financially involved properties. The distance will appear next to the ruler tool.
    • Enter the distances of the first 3 properties of each type in the following fields. (Just type 'n/a' in the relevant box if there are none.)
  • Distance in meters from Financially Involved Properties

  • Distance in meters from Non Financially Involved Properties

  • 7 Select appropriate turbine

    The turbine rating is effectively the maximum power it can output. This output is related to the size and dynamics of the turbine rotor which in turn affect the noise properties of the turbine. The quieter the turbine, the closer it can be to a residential property.

    Using the minimum distance you have measured for Non Financially Involved Properties only , look at the table below to select the turbine with the most appropriate rated output for your location.

    Unsuitable < 100 kW 900 kW 2 MW 3 MW
    Residential - Non Financially Involved < 150
    metres
    150 to 450
    metres
    450 to 620
    metres
    620 to 820
    metres
    > 820
    metres
  • 8 Statutory Designations

    If your land is located nearby statutory designations then a further detailed assessment will be required in order to assess planning sensitivities.

    There are several designations that are likely to cause significant issues if your land lies within them

    Select any of the following designations that your land lies within:

  • 9 Access

    Next it is important to check that it would be possible to access your site with the heavy cranes and large abnormal loads during the installation stage. The longest items are the blades, the widest either the generator or the base of the lower tower section. The latter two items are also very heavy so cannot pass over weak bridges. A summary of typical sizes and weights is provided below:

    Delivery vehicle dimensions and weight

    Turbine size < 100 kW 900 kW 1.5 MW and larger
    Truck length (m) 16.5 standard artic 28 28
    Min Road width (m) 3 4 4
    Min Road clearance width (m) 3 5 6
    Min height above ground (m) 4.6 4.6 5
    Min weight (tonne) 76 120 130
    Max ground slope % 15 12 12

    Generally speaking, if the wind turbine delivery vehicles can access the site then the installation cranes will also be able to access the site without any problems.

    It isn't possible to complete a full access assessment at this stage, but the following checklist will give you a good indication of whether access would be possible at a reasonable cost.

    Please answer the following questions in relation to transport to your site:

  • Can a standard 44 tonne articulated lorries access your site?
  • Are there any tight corners on the route?
  • Are there any weak bridges with no alternative access on the route to your site?
  • Are there any low bridges / tunnels with no alternative access on the route to your site?
  • Are there any excessively steep gradients (more than 16%)?
  • Is the paved road surface at least 3 metres wide throughout the whole route? (wider is even better.)
  • Have you ever had an abnormal load access your site?
  • Approximately how far is the site from an ‘A’ road, in meters
  • 10 Mark the access route from the nearest 'A' road

    Access Route tool

    Access Route tool

    If you have answered positively to the questions above, it may be possible to access your site with a wind turbine. If you can't answer them all positively, it may still be possible but is likely to require more expensive access upgrades. It may also need the agreement of other landowners. We can provide an Initial Access Assessment (IAA) which will give you a clearer idea of what is possible.

    If you think access to your site is feasible, use the "Access Route" tool on the map to indicate the route you would consider most appropriate to the site from the nearest A-road.

  • 11 Grid Connection

    Three-phase 11 kV power lines look like this

    Three-phase 11 kV power lines look like this

    The final check is to ensure there is a suitable grid connection. Single-turbine wind sites generally only need a three-phase 11,000 volt (11 kV) grid power line nearby. Larger developments (typically 5 MW+) may need 33 kV power lines. Higher-voltage lines which are carried on steel pylons have much too high voltage for all but the very largest wind farms – so for smaller projects having pylons nearby is no benefit.

    If you consume a large amount of electricity on-site already you will probably have an 11 kV substation nearby, so it may be possible to grid-connect the wind turbine through your existing on-site distribution system. If this isn't possible it would be desirable to have a three-phase 11 kV power line as close as possible to the proposed wind turbine site.

    33 kW power lines look like this

    33 kW power lines look like this

    Note that three-phase power lines have three wires, and power lines with two wires only have two-phases present and are normally used for single-phase supplies to properties. If you only have two 11 kV wires on your nearest poles, there may be the option to add a third 11 kV conductor to the same poles for a reasonable cost, depending on the length of the upgrade.

    If you have large metal pylons on or near your land, they are 132kV or above and are not suitable for connection of this scale of development.

    Mark grid infrastructure on the map

    Substation

    Substation

    Transformer

    Transformer

    3 phase power line

    3 phase power line

    1 phase power line

    1 phase power line

    Once you have worked out which power lines, ground-mounted substations or pole-mounted transformers you have nearby, mark them on the map. Mark substations using the 'Sub Station' tool, Transformers using the 'Transformer' tool and power lines using the appropriate power line tool - 3 Phase (3 cables) or Single Phase (2 or fewer cables). Just double click when you want to stop drawing the power line.

    Once complete, use the "measure" tool and fill in the answers to the questions below:

  • Even if you have suitable grid infrastructure nearby you will still need to obtain permission to grid-connect the wind turbine from the local Distribution Network Operator (DNO) (note we would handle this later in the feasibility process). The DNO will only grant permission if the grid is suitable.

    The distribution network is getting increasingly congested and occasionally it's not possible to grid-connect a wind turbine, unless you have large on-site loads to consume the energy.

    If you have a strong 11 kV power line close to the site you will have a reasonable chance to connect.

    If you cannot consume the energy on-site or have strong 11 kV power lines nearby you may still be able to obtain permission by paying for a grid upgrade, although this can cost anything from a few tens-of-thousands of pounds to millions. How much you can afford to pay for a grid upgrade will depend on the scale of development and how good the wind turbine site is.


  • Once you have completed the whole form please enter your email address and contact details in the boxes below and press Submit to receive your PDF Wind Self Site Assessment report. This will be emailed to you within a few days and will detail the next steps in the process.

  • Choose a reference name for your site for use in further communications