Fire Board

[Energetic]

I have heard a rumour that MCS inspectors like to see inverters mounted on fireboard due to the high running temps. Is this the case?

Cheers...

 

[JulianC]

First I've heard. Tend to mount them on brickwork in the loft wherever possible, but have seen plenty of inverters mounted on ply boards. I was told that this is perfectly acceptable by an ex-colleague, who has done some MCS assessment work and used to work with the guy who basically wrote the book on UK PV installations. Inverters do run quite hot at times, but not hot enough to warrant fireboard IMHO.

 

[Martin Dawes]

I'd never mount an inverter on ply. I think you should always look for brickwork to mount it.

Furthermore, I personally think that mounting inverters in loft spaces should be avoided.

 

[Markc]

Meter boards are fire retardant, come cut to size and available from the wholesalers. Makes a neat job over trying to drill inverter, AC isolator and possibly two or three (or more) DC isolators to a brick wall. We mount board to a brick surface spaced off the wall with 25mm batten, then fix everything to that.

Inverters in lofts. Interesting how we all think differently. I consider losses over long lengths of DC cable to mount an inverter near the consumer unit for example. There's not much a user can do with an inverter and if they want to know what its doing then add a monitor onto the system. Anyway no great issues wither way really.

 

[Martin Dawes]

I agree that performance-wise, installing an inverter in the loft is obviously beneficial. I wonder if the losses can't be satisfactorarily negated by using large CSA of cable.

I don't like inverters in loft spaces for a variety of reasons. First of all, they're not easily accessible. Although this can be sorted by installing a monitor, this is an expensive option. Secondly, lofts can get very warm. I worry that the ambient temperature will put extra strain on the inverter and shorten its life. Thirdly, I also worry about the fire risk. A faulty inverter could be going bad ways in the loft space and the customer would never know any different. 'Til his roof burnt down of course.

I've only done one install, perhaps I'll change my mind after a few more.

 

[Energetic]

Cheers for the various ideas on that. The reason i ask is our first install is in a bungalow with a loft hatch in the center and the mains at one end. I'll mount the inverter in the loft above the loft hatch on something fireproof directly below the array and run AC 10m or so back to the mains. The only bit of brickwork available is the chimney which i was hoping to avoid. I was going to mount the fireboard or meterboard on the truss... We're going to do displays as standard...

 

[Martin Dawes]

Do you mind me asking what kind of display you're going for? I'd love to include them as standard but I'm very worried that it'll price me out of winning a job.

 

[JulianC]

Inverters in lofts: Standard, accepted practice really. There are safety benefits in keeping the DC runs short and not running them within a property. Doing it to reduce DC losses is a bit of a red herring I feel, if the DC side is wired in the usual 4mm PV cable. This allows for pretty long cable runs before volt drop gets anywhere near the allowed 3% on a G83 domestic system. More of a problem is the 1% drop allowed on the AC side - here there are obvious benefits to mounting the inverter near the CU. Mind you, given that a lot of consumer units I'm seeing on installs are within the property, in a small cupboard or above a doorway for example, I'm not sure how many clients would welcome a Sunny Boy hanging off their living room wall!

For system monitoring, I find customers either aren't bothered and as long as the generation meter keeps clocking up they're happy, or they opt for a SolarLog, which beams daily generation info via the web to our servers for them to view at their leisure. Alternatively, you could fit one of those clamp on energy monitor thingies from someone like Current Cost - about £40 I think.

 

[Markc]

Cheers for the various ideas on that. The reason i ask is our first install is in a bungalow with a loft hatch in the center and the mains at one end. I'll mount the inverter in the loft above the loft hatch on something fireproof directly below the array and run AC 10m or so back to the mains. The only bit of brickwork available is the chimney which i was hoping to avoid. I was going to mount the fireboard or meterboard on the truss... We're going to do displays as standard...

Watch mounting to modern trusses. Some inverters make a noise. This can be transferred down the truss and into the ceiling which make quite a good amplifier. One of our MCS jobs used the Mastervolt 500 inverter. Small little unit but what a din it made. Moved it to the gable end and now can't hear a thing. Good job it was one of our houses as a customer would of gone mad.

 

[Markc]

I agree that performance-wise, installing an inverter in the loft is obviously beneficial. I wonder if the losses can't be satisfactorarily negated by using large CSA of cable.

I don't like inverters in loft spaces for a variety of reasons. First of all, they're not easily accessible. Although this can be sorted by installing a monitor, this is an expensive option. Secondly, lofts can get very warm. I worry that the ambient temperature will put extra strain on the inverter and shorten its life. Thirdly, I also worry about the fire risk. A faulty inverter could be going bad ways in the loft space and the customer would never know any different. 'Til his roof burnt down of course.

I've only done one install, perhaps I'll change my mind after a few more.

All valid points Martin and no great issue either way. Yes a larger DC cable can be used but there again it another size to stock. It is certainly out of sight out of mind in a loft and to be honest some of them weigh a ton to try a get through the loft hatch! Still I like them out of the way but if a client wants it on their utility room wall or alike then that's where it will go. Our next one is going in the garage but that's due to there being no loft space at all. Damn you faulted ceilings!