I'm new to these installs and I've been reading the 690. Articles.
Does the main breaker in the MDP that feeds a backfed MLO panel serve as the disconnecting means or will there need to be another disconnect.
Sent from my iPhone using Tapatalk
The answer is no.* The PV system has its own disconnecting means. Now presumably you have a breaker in the backfed MLO panel which is one disconnecting means, but whether it is the only one you need requires more information to answer.
If you have an inverter, you must have a grouped disconnect by the inverter. (It's 690.13, 14 15 or 16, I forget because the section numbering has changed with the last three code cycles.) If your backfed breaker is 'grouped' with your inverter according to however your inspector interprets 'grouped', then you perhaps can use that as your grouped disconnect. Keep in mind that 705.22 also requires the disconnect for the interactive source to be lockable in the open position. With some breakers, but not all, you can get a padlocking device that stays on the panelboard and serves that purpose. (Not LOTO gear, they make these for permanent install.) In my experience the lockable requirement is rarely enforced compared to the grouped disconnect requirement. However, if it is enforced and you cannot get a padlocking kit, you'll need another disconnect besides the breaker.
If you have micro-inverters, you usually don't need another disconnect besides the breaker(s), although some places may require a rooftop disconnect.
The utility may have additional disconnect requirements that aren't in the NEC.
*[Edit] If your backfed MLO panel is an 'AC combiner' then you may be able to call the breaker feeding it your PV system disconnecting means. But the other comments still apply.
