Figures from trade organisation RenewableUK, show the offshore industry saw a 79% increase in the capacity installed over the period, from 517MW in 2011/12, to 1.5GW in 2012/13.
A further 1.6GW worth of offshore projects received consent and proposals for wind farms with a capacity of 5.6GW submitted to the Planning Inspectorate.
In contrast, between July 2012 and June 2013, 1.3GW of onshore projects were delivered. This is compared with 774MW the year before.
But the capacity of projects receiving consent fell 17% to 1.6GW and submissions were down from 2.7GW to 1.6GW.
The average capacity of consented onshore wind farms fell to just 11MW from 14MW a year before. This was caused by bigger projects struggling to secure construction consent and a lack of suitable large-scale sites.
The proportion of onshore projects that received consent also fell, dropping four percentage points to 68%.
RenewableUK said that it does not expect an increase in new onshore capacity over the next year, but rather that it will be "stable". This would represent the first time this has happened in at least 13 years.
"The market is sitting at a crossroads, we keep thinking it’s going to tip the right way, but we need something to give it a final push," said Maria McCaffrey, RenewableUK CEO.
Confidence in the market took a dent, with only 11% of firms indicating that they expect to invest more than £10 million over the next 18 months, compared with 22% previously.
There was also a decline in the number of companies planning to take on new employees, with only 58% indicating that they will, compared with 70% a year before.
"This is not too catastrophic at the moment, but if it continues for another year then it would certainly be a worrying sign," said Maf Smith, RenwableUK deputy CEO.
However, Smith indicated that the body expects to see a drop in offshore wind farms going online next year as the round two projects come to an end, but before round three projects can be completed.
The "period of reflection" relating to uncertainty over the Electricity Market Reform bill is also contributing to this, he said.