Pv & smoke alarms !!!!!

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kme

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This is currently awaiting clarification, but could end up being an even bigger issue than the "back-fed RCD & its effect on disconnection times"

So, it seems as though at least one of the smoke alarm manufacturers (starts with an A - 4 letters) has said that any warranty on their products is void if installed in a premises with PV in - may cause failure of said units!!!!! Cause is given as the "non-sine" wave when the PV is on damaging the electronics!

Initial thought: That`s grim! So if there is a fire, and the alarms don`t operate - who is going to be liable? Probably the guy who installed either the PV or the alarms, whichever came last.

But.......there has been talk that nearby properties, on the same phase, are also having poor quality waves. Aside from the fact that I wonder if you need to use more "dirty" electric to get the same result as "clean" 50hz sine - what if your neighbour`s PV stuffs up your smoke alarms, or vice versa?

What can you do? Write to everyone you`ve installed a system with, and advise them that the PV may not be compatible with any mains powered smoke alarms in the premises? Does that get you out of the (possible) future crapstorm that is awaiting an unsuspecting sparkykins down the road??

Is it in their instructions? I`ve got some in the van - so I`ll have a look at `em tomorrow!

WTF is going to be next? we get sued for shortening the life of all appliances in a property? If this "dirty" leccie is soooooooo bad, surely the inverter manufacturers have to shoulder a percentage of the blame.

 
but......without an incoming supply; it shuts down anyway. I DO need to get a `scope trace of a PV property - with / without the inverter running.

It`d also be nice to look at "next door`s" waveform - if we`re looking at a sawtooth-esque shape, then it could have implications!

I`ve just looked through the smokies website - but no mention to be seen. I only heard about this tonight, so feeling a bit like a mushroom - and a little concerned that I may have inadvertently snafu`d someone smoke detection system without knowing!!!!! :(

 
but......without an incoming supply; it shuts down anyway. I DO need to get a `scope trace of a PV property - with / without the inverter running.It`d also be nice to look at "next door`s" waveform - if we`re looking at a sawtooth-esque shape, then it could have implications!

I`ve just looked through the smokies website - but no mention to be seen. I only heard about this tonight, so feeling a bit like a mushroom - and a little concerned that I may have inadvertently snafu`d someone smoke detection system without knowing!!!!! :(
DAVE your services are needed!

Another mini project for you;)

 
This def sounds very scary.
Fixed that for you, Gav ;)

---------- Post Auto-Merged at 23:49 ---------- Previous post was made at 23:47 ----------

DAVE your services are needed!Another mini project for you;)
Aye - you`ve got a `scope, haven`t you bud? Want to stuff it on your incomer, and video the results?????? : bad day explode

 
Would it be possible to put it into simple terms? I think I got it but as I'm a student my self I'm not 100 percent sure.

 
I fitted an aico test switch 2 months ago and it was written in the instructions of it.

So I can confirm but have no further details.

 
Would it be possible to put it into simple terms? I think I got it but as I'm a student my self I'm not 100 percent sure.
I`ll try - but Mr. Artois is busy messing my head up ]:)

EVERYTHING we buy for use with mains electricity in this country, is expecting to be given a"pure" 50Hz (cycles/sec) sine wave.

Most of the kit that produces renewable energy throws out DC, with varying voltage/current characteristics. So we have an inverter that takes this DC, and converts it into AC, at 50Hz. Cleverly, it matches the frequency of the incoming supply - saves a big bang:)

UN-cleverly, they don`t pay much attention to the "quality" of the wave they output - a couple of inductive loads "smooths" out the shape somewhat.

Now, a lot of electronic kit wants fairly low DC voltages to operate - so they use either "switch mode" power supplies; or a step-down transformer, diodes (bridge rectifier?) and capacitors to reduce the ripple.

All this work well on a true sine wave - not so good on rougher waves (like a jet engine being expected to work with unleaded from a garage) - it isn`t refined enough.

Some companies are suggesting that the poor quality wave is smoothed by the grid, which is smooth, and soooooooooooooooo much bigger.

Other don`t think it does, and that you could have a "bad" enough waveform to damage power supplies that were never designed to deal with that amount of degradation in quality.

Does that help?

 
apart from the JET engine bit,

they actually use a less refined fuel then an oil burner! believe it or not,

they run on a really poor version of diesel!

unless I have been misinformed on a massive scale,!

thats why the term AVGAS is badly used by a lot of the motorcycling community.

 
Apparently the NIC gave guidance about this issue towards the end of last year, and manufactuers of smokes have been saying it for longer. YET you search it online and youll find it very hard to come across a thing. The lack of information is stupid for something as potentially dangerous as this.

But where does it stop soon we will have to check everything in the property, where do we draw the line on what were responsible for and what should of been addressed by manufacterers and regulators long ago.

 
This info has been around for quite a while, and basically relates to poor quality inverters outputting badly rectified sine waves. Personally I think it's about time Aico sorted out their smoke alarms and built in some simple protection to the units, as it's not just PV that upsets them.

 
Thanks kme that clarified things for me :) sounds like a big problem and a big grey area too. Who is liable if anything goes wrong? The electrician who installs the smokes? The person who installs the pv system or the manufacturers who produce smoke equipment?

 
Interesting thread. Well now I know one make of smoke alarm to avoid.

With regard to choppy or noisy sine waves, when I was developing my Solar PV dump controller, I had a good look at the current waveforms (I never looked at the voltage waveforms, just current). My Sunnyboy inverter seems to output a very clean sine wave, so I can't see any problems there.

What I did find is my washing machine has the most horrendous choppy, dirty, non sinusoidal current (consumption) waveform I have ever seen. So would that upset that particular brand of smoke alarm that doesn't like noisy waveforms?

TBH this just sounds to me like a convenient get out clause, a bit like fan manufacturers insisting on a 3A fuse, only with much more serious consequences.

 
I would say it could be the owner of the house at fault, they should ensure they test the detectors weekly meaning any problem would arise sooner rather than later.

---------- Post Auto-Merged at 11:48 ---------- Previous post was made at 11:47 ----------

Unless you actively installed a smoke alarm etc without regard for manufactures instructions

 
Aico have had warnings in their instructions for years, I thought it was another area the PV industry ignored.

Im sure I read anything but a good sinewave may cause heating of the alarm.

How can it be the homeowners fault if you install something that breaks something working fine? And should smoke alarms change to facilitate PV installs or the other way round?

In practice I think its a bum covering exercise if there was a real and common problem surely we would have been replacing alot of detectors by now.

 
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