Just had a quick run through the document it does seem to be addressing a lot of the issues that have been discussed a number of times on this forum, including mounting systems, loading, wind loading etc - also covers the competent person scheme building regs etc, - seems like the MCS scheme will use this to enforce regulations rather than their own documents - possibly a good thing.
Comments on distance from edge of roofs like:
"For a domestic roof, a suitable minimum clearance zone is around 40-50cm." - it then goes on to explain why
It lists these changed areas:
* Notification to DNO’s referencing changes to Engineering Recommendations G83/2 and G59/2
* Updates to BS7671
* Earthing & Bonding
* Application of RCD’s
* Performance estimates
* Wind uplift calculations
Some inital comments - these are just thoughts and would welcome a debate!
Change: Array Earthing or Bonding:
Flowchart clarified, simplified and comprehensive guidleines given.
Result: Simple to follow guidelines.
Change: AC Isolation:
An accessible means of isolation shall be provided to isolate the a.c. circuit . MCB’s, RCD’s and main switches installed in accordance with
BS7671 and in an accessible location can be used to fulfil the requirements for an accessible means of isolation
Result:
Means that only an MCB needs to be provided at connection to the incoming mains - no seperate isolators.
** MCBs are allowed by BS7671 to be used as a means of isolation (Table 53.4 - was Table 53.2) (for TT or IT it'll need to be adouble pole one)
Incoming=>Meter=>MCB=>Total Generation Meter=>Lockable in off position only isolator Near Inverter=>Inverter
Presumably it could also be TotalGeneration Meter=>MCB
And, is a single pole MCB acceptable? - it appears to be so (see also the updated example configuration diagram)
Change: RCD Protection:
Cleared up, simple flow chart so SMA, Fronius, Power-One etc OK and correct with the advice they have been giving.
Also, see this:
"The final connection into a distribution board that contains one or more circuits protected by an RCD, shall be made in such a way that the outgoing circuit for the PV system is not connected into the outgoing side of an RCD installed for the protection of other circuits (ie in a split board – connected into the part not protected by the RCD) ."
Result:
So generally it would not be RCD protected, if it needs to be then it needs it's own RCD of the correct specification.
Change: Output Calculations:
Upside: SAP Replaced with a more accurate analysis, location, azimuth, inclination, shading.
Downside: Still ignores panel and inverter performance.
