Vestas V44 Retrofit by Heritage Wind Energy

Heritage Sustainable Energy is a well-established renewable energy provider that primarily deals in utility-scale wind energy projects in the State of Michigan, US. Heritage contacted Mita-Teknik after a recent purchase of a decommissioned Vestas V44 turbine presented the company with some serious performance issues.


The Vestas V44 had been operated by a local utility company since 1996, but problems with the RCC and generator meant that the turbine was not running well, had many outages, and low availability. After several unsuccessful attempts to repair the turbine, it was disconnected and left to sit for 2 years before the utility decided to sell it. Then Heritage acquired the unit.

Heritage completely rebuilt the hydraulics, the pitch system, and brakes. Heritage also ‘tweaked’ the original control system and did smaller tasks such as changing fluids, rewiring, and cleaning the turbine.

After the initial efforts to get the turbine back to life, re-occurring issues with the existing controller made Heritage look to alternative solutions for how to control and operate it.

Issues included:

  • Difficulties acquiring spare parts
  • Random controller faults
  • Controller ‘overload’ – struggling to operate
  • No remote connection
  • No feasible repair options
  • Issues with faulty RCC unit


Mita-Teknik supplied Heritage with the WP3500 controller Retrofit solution, including the Service Applet, which is a tool designed specifically to speed up the work tasks for service personnel doing service and maintenance on Mita-Teknik controlled wind turbines.

The new solution enables Heritage to override the RCC and ‘bump up’ power. Also, all data is now available through SCADA.

Commissioning took a mere 6 hours, and was carried out by Heritage’s own engineers with online and phone support from Mita-Teknik.


After retrofitting the V44, the turbine has been performing with great success, with 100 % availability in May, 99,79 % in June, and 99,88 % in July.

Heritage recently began maintenance on the V44 turbine, and the Service Applet got recognized by the service team for its functionality and high user-friendliness.

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