AC cable run 100m info on voltage drop

[stubo300]

i have been asked to pv quote for a barn which is 100 meters away, there is a 16mm cable running down to the barn,
my question is according to the sma software the voltage drop is 3.74v the power loss is 63 Watts

is this ok, i know the dti says you should try and keep the voltage drop below 1% but what if it is not possible

 

[bugsy]

you really dont wonna replace that cable do you !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!111 doing a Duram,

 

[Markc]

i have been asked to pv quote for a barn which is 100 meters away, there is a 16mm cable running down to the barn,
my question is according to the sma software the voltage drop is 3.74v the power loss is 63 Watts

is this ok, i know the dti says you should try and keep the voltage drop below 1% but what if it is not possible

It will result in the generation meter not recording some generation. The inverter possibly cutting out on peak output and a loss in yield.

Why is 1% not possible? Is it solely down to cable cost? If you explain this to your client then they may be prepared to replace it.

 

[Ramjam]

If the generation meter is co-located with the inverter then the losses would not reduce the meter reading I think????

 

[edexlab]

I think both Markc and Ramjam have valid points ,I can't see a problem with siting the Meter next to inverter ,the Dno might as they'll be the ones losing out but they'll have a few quid to spare from surveys/witness tests etc

the only real issue is the added cost of a correctly sized cable on your quote versus the lads fitting from boxes who know little/ nothing about the design issues ,and with luck they'll be found out quite quickly.

hopefully with systems costing what they do and a more discerning customer base this will happen it would be sad to see it go the way of double glazing and the like.

anyway when we're faced with a large cable run we explain the reasons why and let them make their own mind up ie do they use somone who knows
and explains issues or someone who does'nt mention it .

personally we aim for the 1% Vd recommendation and I would price for another cable as with existing loading plus pv system I would'nt be happy with the csa but thats for the installer to decide

 

[Ramjam]

I think that's the only honest answer, offer to put the meter co-located with the inverter to ensure that everything generated is recorded then explain that the cable run is less than optimal and offer a price to replace. Some customers want everything right, others wont care as long as it's safe and it pays. Note it in the comments box on the install certificate and move on that way nobody can accuse you of having cut corners or just not having understood what you were doing?

 

[Engineer54]

Rather than replace the existing 16mm cable, it would surely be more cost effective to paralell the existing cable!!!

 

[stubo300]

cheers