I don't see anything odd about it. kWh (kW

__times__ hours, not 'kW per {i.e. divided by} hours) is simply a measure of energy, and one can add up amounts of energy over any period you want. If your immersion heater uses on average, say, 5kWh of energy each day, there's no reason why you can't multiply that by 365 to get the total energy used 'per year' of 1825 kWh. A 'kWy', on the other hand, would be an average power of 1kW continuously for one year - i.e. 8760 kWh.

"33 kWh per month" = "26% of its capacity" so 127 kWh must be full capacity. A month as unit of time = 28 days (does not refer to calendar month) which means 1655 kWh per year.

They

__do__ effectively refer to calender months. Their average figure of 33 kWh per month results from dividing 585 kWh by the corresponding 18 calendar month period (Jan 2012 - July 1013, I assume inclusive). The '100%' capacity they are implying would therefore be 1525 kWh per year, rather than your 1655 kWh.

I think using kWh is rather confusing 1 watt = I Joule per second so 1 kW = 3600 kilojoules per hour so 1655 kWh = 5956 MJ so why use kWh rather than Joules?

As you indicate, kWh and MJ are totally interchangeable units of energy - so you can use either you wish. KWh is probably more easily conceptualised by most people, since they have some understanding of both kW and hours, but most don't have a clue what a Joule is.

"A turbine this size should produce around 422357 MJ per year which is a significant amount of power." make sense but how can you have per hour per year?

As above, (a), whether one gives the figure in kWH or MJ is irrelevant (no different from quoting a distance in km rather than miles) and (b) it is

**not** "

__per__ ('divided by') hour, per year" - is is "

__for__ ('times') hours, per year". As above, there's nothing wrong with adding up the total energy generation (in kWh or MJ) over a year (or any other period).

Also how can 1655 kWh = 9000 kWh? Is my maths really that bad?

As above, it should probably be 1525 kWh, not 1655 kWh. However, if I understand, I think that you have probably missed the whole point of the article. As far as I can see, they are saying that 'a turbine of this size'

__should, if appropriately located__, be able to generate 9000 kWh per year, but that it has been so badly located that, even at 100% capacity, it would only produce about 1525 kWh per year.

Kind Regards, John