Damp inside solar MC4 electrical connectors

Question

Has anyone else thought - "my solar panels should not have been installed in the rain / damp weather"? 
 My solar panel installer company claims it's OK to install on the roof in all weathers, all year. Rain did get inside my connectors, and the roofer plugged the connectors together anyway. The damp will never escape the IP68 (= waterproof) connector, and so will corrode the (tinned) electrical contacts within. 
 It seems a fact that the corrosion will stop the system working within a year to two, and most certainly within the 10/25-year guarantee. 
 What do other engineers think? And did you complain? 
 If enough IET electrical engineers who had solar installed all agree, then finally the solar installation industry will have to listen. 
 Cheers, Adrian .

Jam · Accepted Answer

Manufacturers will tell you their connectors are only weatherproof when they have been assembled correctly (torqued up etc) and mated with a matching connector per instructions. For example, Staubli MC4 Evo-2 is IP68 when mated, but only IP2X unmated. 
 I have seen the after-effects of "MC4s" (from various manufacturers) installed in poor conditions without due care, or where damp is otherwise is allowed in, and from a large enough batch some will indeed fail. It is an issue the utility-scale solar industry is aware of at least. Whether domestic installers stop to think about it I couldn't say; as with everything in domestics I suspect it varies. 
 This does not necessarily mean that installs should never take place in poor weather, but that when it is, measures should be taken to keep the connectors dry until they're mated and checked. Indeed on larger constructions measures may need to be taken even in dry weather if it is likely to rain (or get dusty) twixt making up connectors and mating them. Fortunately the design of a made-off connector work in one's favour such that external damp surfaces can be safely wiped dry while the risk of water getting directly insde is more from being left in pools of water, on the ground or clipped in running streams, rather than an errant rain-drop under a light mist... but I would not (and do not) accept wet connectors being mated and am absolutely not above requiring cables to be reterminated where there is a risk of damp. 
 End caps are available if they are to be left exposed for a period, but less high-tech solutions are normally adequate for temporary situations. 
 Meanwhile if it's really hammering it down, is that the best time to be sat on a roof working with live 1000Vdc, from an EAWR perspective? Note again that until they're mated the connectors are only IP2X, and there may well be no means of isolation. 
 Hope that helps

Damp inside solar MC4 electrical connectors

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