As an experiment, this year I have my chillies in three locations: one is in pots lined up against a south-facing wall, getting direct sun from about 10am, others in pots lined up against a west-facing wall getting sun from about midday, but slighly longer in the evening, the third the ground in a location only getting about 3 hours direct sun a day, and more dappled light at other times. The ones in pots against the wall are covered in fruit, though the ones on the west-facing wall were a bit slower. The ones in the ground have hardly any. (I don't have a greenhouse.)

So there you are, keep em warm and give em a lot of direct sunlight, and they do fine out of doors. If you are doing that already, then don't know. Though some varieties are a bit shy and only do well if kept very warm and bright. If you are growing them in a greenhouse, well don't know about that either.