Generally 6mm twin and earth for AC side , even on smaller systems, and we usually replace the mains board with an RCBO filled board as part of the PV project at 5% VAT as associated works. Usually 6mm for DC side. Volt drop never an issue on either side.
We are ECA members and they are not keen on split RCD, 17th edition boards due to reg 314.2.
The customer then gets a certificate covering the whole property. They get a far better job, no other circuit ever takes out the PV system.
Less circuit time off = better returns.
The customer knows we went the extra mile, we get recommended , the ball keeps rolling....faster
Obviously we are using Sanyo (90% of time) and doing the RCBO board so our profit is not as good as some companies using lesser equipment but long term our customers will gain and so therefore should we. We are still servicing our 20year electrical customer base and will still be around after the PV bubble bursts so have taken the decision to not drop below a certain standard.
Like you we have lost jobs to people claiming Sharp, Kioto, Kyocera ,Dimplex, Upsolar and Yingli are the dogs dangly bits but these customers will work out in time they have been hoodwinked, usually by a suited shark.
We give out lists of thirty customer installation photographs with phone numbers and tell the prospective customer to contact one one , some or all of them at the time we do the survey, we also hand them the Sanyo test results, and OKO and Photon reports so that if someone else is quoting they know the truth about products promoted by others.
We also tell them we can give them another thirty contact details if they want them and point them towards the testimonials on the web site.
Then we send them a quote.
We also have customers whose systems are over a year old which helps when some competitor (clown) tries to sell a 4kW system producing 6000 kWhrs a year !
