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Solar PV System - Maybe a stupid Question but ....
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Posts: 227 Forumite
If I have an 16 panel system installed on my roof and taking into consideration that panels do degrade over time. How will I know if one panel is degrading faster than the other panels and maybe outside the manufacturers specification?
It's been mention in this forum that new panels over achieve by upto 20%! Great but what if one panel is only producing 50% of its design target due to a fault or degradation, it will be masked by the other panels over production.
F.
It's been mention in this forum that new panels over achieve by upto 20%! Great but what if one panel is only producing 50% of its design target due to a fault or degradation, it will be masked by the other panels over production.
F.
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Comments
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Certainly not a stupid question.
You will know if there is a big problem from your generation meter, but if a single panel has a problem you won't know.
No installer is going to come back and individually check out your panels - scaffolding required etc - to diagnose a degredation in performance.0 -
HiIf I have an 18 panel system installed on my roof and taking into consideration that panels do degrade over time. How will I know if one panel is degrading faster than the other panels and maybe outside the manufacturers specification?
It's been mention in this forum that new panels over achieve by upto 20%! Great but what if one panel is only producing 50% of its design target due to a fault or degradation, it will be masked by the other panels over production.
F.
With an 18 panels system you will have more than one string .... I use SunnyExplorer to compare the performance of my strings, if an imbalance appears between their output there must be a problem on a panel in the lower performing string .....
One underperforming panel will pull down the performance of all panels within the string, that's why a decent installer will test the panels and group them into partially matched strings in order to maximise the performance of your array from the panel pack received ....
HTH
Z"We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
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Certainly not a stupid question.
You will know if there is a big problem from your generation meter, but if a single panel has a problem you won't know.
No installer is going to come back and individually check out your panels - scaffolding required etc - to diagnose a degredation in performance.
Isn't it feasible, at the point of installation, for some kind of patch board to be incorporated into the loft space where individual panel readings could be taken with the use of a DVM?Hi
With an 18 panels system you will have more than one string .... I use SunnyExplorer to compare the performance of my strings, if an imbalance appears between their output there must be a problem on a panel in the lower performing string .....
One underperforming panel will pull down the performance of all panels within the string, that's why a decent installer will test the panels and group them into partially matched strings in order to maximise the performance of your array from the panel pack received ....
HTH
Z
Hi, the 18 panel system should have read 16 panels, I have corrected it now. I was quoted for 16 x Sharp NU250 and was curious as to how a faulty/underachieving panel would be identified.
F.0 -
HiIsn't it feasible, at the point of installation, for some kind of patch board to be incorporated into the loft space where individual panel readings could be taken with the use of a DVM?
Hi, the 18 panel system should have read 16 panels, I have corrected it now. I was quoted for 16 x Sharp NU250 and was curious as to how a faulty/underachieving panel would be identified.
F.
The problem with the patch panel solution is that the panels need to be operated in series to achieve the voltage for a central inverter ... I suppose that it could be possible for the manufacturers to build individual panel diagnostics into their products but this would need an industry-wide diagnostics communication standard to be developed which the inverter manufacturers could use ... I wouldn't hold my breath on that one, FiTs will probably be winding up by the time anything would be ready to release
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I believe that individual panel performance can be monitored with most makes of micro-inverter, but you'd be paying well over the odds for a less efficient system if there was no other reason for not using a central inverter. Another option could be to use DC/DC power optimizers such as these ... http://www.solaredge.com/groups/powerbox-power-optimizer which are effectively individual MPPTs, but then again I think that this would probably add in the region of £1000+ to a 16 panel system (I believe that they're about £60 each) .... you might also be interested in this article on the various technologies and how they integrate/compare ... http://www.solarserver.com/solar-magazine/solar-report/solar-report/microinverters-and-power-optimizers-perspectives-of-distributed-pv-system-architecture-in-the-residential-market.html ... I saw something recently that suggests that SMA were looking at (/had looked at) similar DC/DC devices as a solution to shading issues which makes sense as they purchased Dutch micro-inverter manufacturer OKE some time ago ....
HTH
Z"We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle0 -
I was just seeing the whole PV array as resistors connected in series (*) and that it should be possible to connect a voltmeter across each panel. This would then indicate the voltage produced by that individual panel.
Perhaps the cable from each panel could be brought to the proposed patch panel before connection to the next panel ... its only wire!
(*) clearly they're not resistors but for the sake of an analogy and my 'O' level physics.
F.0 -
I see your point, but this would effectively add around 80 to 100 meters of cable run & associated cable losses on my system of somewhere over 1%, along with effectively doubling the number of likely points of failure .... joints. It would be quite easy to test individual panel performance when something fails or degrades though ... unless the failure is a connection at the panel end ...I was just seeing the whole PV array as resistors connected in series (*) and that it should be possible to connect a voltmeter across each panel. This would then indicate the voltage produced by that individual panel.
Perhaps the cable from each panel could be brought to the proposed patch panel before connection to the next panel ... its only wire!
(*) clearly they're not resistors but for the sake of an analogy and my 'O' level physics.
F.
Z"We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle0 -
My point was more that most installers will have zero interest in 'after sales' support, unless there is some remuneration.
This was discussed in another thread. Take a scenario where a panel failed(partially or completely) in the guarantee period. Would Sharp or any manufacturer be prepared to pay for scaffolding(health and safety!!) and labour for diagnosis and replacement of panel?0
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