Practical considerations for developing a wind project

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Published: September 2011

Choosing the correct size of wind turbine, supplier and product is not easy. Larger turbines in the small to medium sized range (below 50m tip height) are becoming much more popular.  In the past few years the sub 15kW wind turbine has proved a popular choice but we have seen a dramatic switch to 20-50kW and above, with customers who have a good three phase power supply. Dairy farmers and large arable farms would be self sufficient in power (150,000 kWhrs) if they installed a 50kW on a good 5+ metres per second wind speed site. The real beauty of the 50kW is that it can sit on an 18m tower (towers from 18-36m) which is good for achieving planning consents in sensitive areas and most three phase lines will take 50kW without a major upgrade.

Grid connection is as important to your wind turbine project as planning because only when you have both, then your project becomes viable. If you have a three phase line to your property then connections costs are generally low for smaller turbines below 50 kW.  If you are limited to a single phase line this will significantly reduce your turbine options unless you can afford to upgrade your connection.  The upgrade fee may vary from a few thousand pounds to much higher sums and the customer will need to weigh up the viability of these costs before the wind turbine project can proceed.   When grid connection is not known or too expensive then your project can become unviable. This could change in the future when off grid technology such as batteries are more achievable. Always demand a copy of grid connection papers (and planning permission documents) before ordering your wind turbine on site. In some instances the Power Company can take months to do any upgrade work if needed. The customer always has to pay first then the work can commence.

While larger turbines do not go through a formal product certification process, those below 50kW need to be MCS certified.  This is an independent test to ensure output figures are achievable. There is a list available on the MCS certified products page of approved wind turbines.  If your chosen wind turbine is NOT MCS certified then your project may well become unviable as you will be unable to claim FITs. If your wind turbine is not currently MCS certified this is a considerable risk – even if the manufacturer assures you “it’s in the latter stages of certification”.  If you are committed to this make/model of turbine then it may be better to wait until it has become formally certified. There are a good half dozen wind turbines below 50kW that are MCS certified. Some are suitable for single phase connections where, in most cases, Power Companies will not allow more than 17kW down a single phase line.

When choosing a wind turbine, do your homework as that machine will be with you for over 20 years. A turbine in its working life will clock up 140,000 spinning hours during the 20 years feed in tariff period, where as a tractor will do 14,000 hours and need a major refurbishment. You can trade in a tractor, but you don’t want to be trading in your turbine after 10 years. You only get one chance at choosing the correct turbine and so you need the best advice possible across a range of options.  If you don’t get planning permission for a large turbine you can always fall back to a small scale one.

Even before planning and grid connection has been explored an important step is to look at financing the project - unless you already have your own source of cash in the bank.  The products that you install should be both bankable and insurable with your lender otherwise you will not get a loan for the project. If you are having difficulty finding finance for your project most reputable high street banks or finance companies have funds to target renewables projects. They have recognised the important future that renewables have in the agricultural, industrial and domestic market. Before financing, it is important to ask for a copy of the warranty documentation and the product specification manual of the wind turbine. This gives the lender confidence that the product is reliable and has a well known history. 


Single phase limit


I am surprised to read that you can send up to 17kW down a single phase.
My understanding was that G83 limits the input to a single phase to 16A which works out to 3.68kW on 230V. Can you clarify this?