The first Project Ara hardware was due to be trialled in Puerto Rico this year, but has been pushed back to at least 2016.
The trial will take place in a new location in the US, the Project Ara team said via a series of tweets.
The team blamed "lots of iterations" in the design, which was first shown off in 2013, for the delay.
Project Ara is Google's intriguing attempt at creating a smartphone that comes in bits.
It means certain components can be added or taken away without the need for intricate alterations to the phone.
It would potentially mean smashed screens or worn batteries would be less costly to replace - as well as allowing others to create bespoke hardware for specific tasks.
Google had planned to offer around 20 to 30 different modules for the Puerto Rico trial.
In a series of tweets, the team told followers that "#Project Ara isn't going anywhere", but said it had been set back by "Lots of iterationsâ€¦ more than we thought".
The first public demonstration of the technology, at Google's I/O developers conference in May, was well-received.
Writing on a forum for developers interested in working on Project Ara, San Francisco based designer Garrett Kinsman said he felt a "sense of overwhelming sadness" at the delay.
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Google has delayed its plans to trial its modular smartphone concept, codenamed Project Ara.