My name is Bryan Rendall, director of Bryan J Rendall (Electrical) Ltd, the company in Orkney who installed Pete Henderson and family's turbine system.
I see that this incident has understandably generated a lot of interest and following investigations, we have some information that will help set the record straight on exactly what happened.
We have identified an assembly error in Mr Hendersons turbine, whereby our technicians who installed the turbine, made an error in fitting the wedges which interface the blades to the hub. The result of this error was that the blade pitch was wrong, and caused the turbine to run much faster than it should have. This higher RPM generated a significant overvoltage, compared to the design voltage, and accordingly caused 3 capacitors in the SMA inverter to fail. The effects of this failure is well documented in Peters post above.
As soon as we became aware of the problem with Mr Hendersons turbine, we attended to his property and removed the inverter for further examination. That, along with input from Proven Energy Ltd. pointed to a blade fitment problem, which was confirmed last week.
We have installed many turbines all over Scotland, including quite a number of grid connected Proven 6 kW ones, and it was very concerning to us that our installation procedures allowed this error to occur. We have modified these procedures accordingly to ensure that such as mistake does not happen again.
We are also liaising closely with both Mr Henderson, and Proven Energy Ltd, to ensure that we can all reach a satisfactory conclusion.
There are a few points I must emphasise though.
1. The failure of Mr Hendersons inverter is an isolated incident which arose from incorrect turbine assembly on site. This led to a massive overvoltage and failure on the DC bus capacitors.
2. This overvoltage incident is completely unrelated to any other overvoltaging that may be experienced on turbines which have been assembled correctly, in certain high wind conditions, if the turbine is unloaded. This may result in a mild overvoltage, with marginally over 600 volts produced on the output of the turbine controller. To date, we have not experienced any lasting over-voltage problems in grid connected turbines, when the turbine is installed fully in accordance with Proven instructions.
3. We are very concerned that this incident occurred, when we have procudures to make sure turbines are correctly installed and commisioned. Procedures have been modified to ensure a re-occurance is avoided.
4. We are very sorry for the concern which has been generated within the Proven Owners Community. We are also very sorry for the distress which Mr Henderson and his family suffered at the time of the incident, as well as any less than favourable reflection this incident has had on Proven turbines. To both the Hendersons and Proven Energy Ltd, we apologise for this.
Aside from this posting, we will be communicating the findings of the investigation to all concerned, including Trading Standards.
Bryan J Rendall (Electrical) Ltd.