low output until all panels in sun

[oliver s]

I think its hard to say exactly what is causing that as there are a number of issues that need to be sorted as others have said any shading is also a big issue in general it all needs sorting

 

[The Solar King]

Yes, that's the one. Would have been amazed if DC isolation had been excluded.
The AC side is somewhat interesting to say the least. The run to the the consumer unit is unlikely to be very long so 4mm T/E would be adequate. Without knowing the rating/sizing of the cable currently fitted it is difficult to comment further. It does however look a little small.

 

[dansk]

I'll second that, take a look here for examples of how it should be done http://www.electriciansforums.net/p...87-ef-members-installs-show-us-your-work.html

 

[davey_b]

Ok so what would your list of things to sort be? That gives me an idea of what to ask of the installer.

 

[davey_b]

Yes, that's the one. Would have been amazed if DC isolation had been excluded.
The AC side is somewhat interesting to say the least. The run to the the consumer unit is unlikely to be very long so 4mm T/E would be adequate. Without knowing the rating/sizing of the cable currently fitted it is difficult to comment further. It does however look a little small.

Run to the consumer unit is about 40m because our house is a u shape and the consumer unit is on the other side of the house.

Just to clarify there is no separate isolator like the ac ones between the panels and the inverter. The cables come straight from the panels to the inverter. The inverter has a switch on the side of it which is called dc insulation switch in the inverter documentation. How though would you stop current coming down the cables from the panels to swap them over etc.? Or isn't that an issue?

 

[dansk]

http://www.electriciansforums.net/a...stalls-show-us-your-work-dsc04699-medium-.jpg that's an example of a decent set up. can you see the differnce.

 

[oliver s]

1, install cables from array in conduit. 2, Install correct size cable from the isolator to the generation meter (either 4 or 6mm depending on calculations) 3, Install DC isolators even though already included on the inverter just makes a better job, and ease of testing, 4, Full test report on all individual panels and strings including polarity, 6, Fire proof board behind inverter 7, All warning labels system schematics to be in the right places. 8, Resolve shading issue by moving panels, optimisers etc Once all resolved you should have got to the bottom of what is causing the poor generation or could just be a combination of a few things

 

[solarfred]

ie. an MCS approved installation following the DTI guidelines which is what you were paying for. And you need another AC isolator at the consumer unit which is not in the same "room" as the inverter. So the installer is going to have to spend cash sorting this out correctly which is most unlikely in my opinon. If it was not for the shading issue this installation would never have been highlighted. Quite how you are going to test the individual panels now is another issue.

 

[The Solar King]

With built in DC isolator not an issue. Start up and shut down procedures must be followed. Like others commenting, I made an assumption about your property from the external shots. At 40m, 4mm cable would not be adequate as the voltage drop would be over 3% where the regs require less than 1%. Therefore 6mm is required.

Please leave everything to a qualified installer.

 

[davey_b]

With built in DC isolator not an issue. Start up and shut down procedures must be followed. Like others commenting, I made an assumption about your property from the external shots. At 40m, 4mm cable would not be adequate as the voltage drop would be over 3% where the regs require less than 1%. Therefore 6mm is required.

Please leave everything to a qualified installer.

I'm not thinking of doing it myself. I just want to understand how and why so that if am told something I know if it's crap to palm me off or not.

 

[whinmoor]

Give us a broad indication of where you are in the country and one of the guys from here might be prepared to pop around and give it a "once-over". I suspect that the list of issues might grow even longer.

 

[davey_b]

Lesmahagow, just south of Glasgow.

Cheers

 

[whinmoor]

Sorry, well off our patch but the forum has a few members from north of the border who might be able to help but the general principles and standards are the same nationwide.

You've received a fair few indications of issues to raise when you invite the installer around to discuss the matter. Have you checked whether they are still trading? With workmanship like this they may have gone under rather than deal with warranty claims. Did you get an insurance-backed warranty?

 

[rocker55]

Davey, I am in Inverness and have exactly the same type of panels and inverter as you.
I could give you a reading of what i am generating daily over the last few weeks as a comparison.
Direct Solar fitted mine and it looks like the same type of installation - Shoddy.
I don't have a hand held meter like you are holding though, if I want to know what I'm making it's up to the loft I go.
I am going to hook it up to ethernet eventually when I get round to it.
I've been getting around 20 odd KWH daily this month, with a 4kw instalation, split over my roof, e.g. 8 panels on each side.
My gable end of my bungalow is south facing meaninig my roof is an east/west split.
I thought the installers were wrong in doing a split but wonder if I am losing out when the sun comes over the top of the roof and leaves the east facing panels behind.
I look forward to reading more comments in the morning.
Steve.

 

[pvman]

Hi Davey_b

We are in Edinburgh and would be happy to give you a quote so correct the problems. I know Iain at Tigo so could install optimizers if required, although it may not need it.

Regards

Tom

 

[davey_b]

Hi Davey_b

We are in Edinburgh and would be happy to give you a quote so correct the problems. I know Iain at Tigo so could install optimizers if required, although it may not need it.

Regards

Tom

Cheers.

To be honest if the original installer (they're still trading) doesn't do it as part of the original install I'm going to tell them to come and take it away because at this output I'd be better putting the money in an ISA.

 

[pvman]

Cheers.

To be honest if the original installer (they're still trading) doesn't do it as part of the original install I'm going to tell them to come and take it away because at this output I'd be better putting the money in an ISA.

No problem, Without seeing the site it is hard to be sure but I don't think the issue is with solar, it is with the install. As others have said using PV sol would show shading and provide an accurate prediction on what you should generate.

Tom

 

[Earthstore]

Well, you have had lots of good advice there, but after seeing the pics, and reading all the advice, I do not think that optimisers are the answer for you, In certain circumstances they can be beneficial though.

Firstly, you need to get the two panels out of the shade, either move them or cut the trees, remember that those trees will grow so in 10 years they may shade 4 panels...
It looks like you have space to move 4, just a suggestion.

Also the install needs sorting, that silly bit of flex they have used will/can cause your inverter to go overvoltage, something that some companies do not understand, I think someone did the calcs and said you need 6mm which is always a safe size to use anyway for a domestic install.

I understand your frustration with all of this, but get the system sorted, properly, if it was working as it should you would be over the moon.

My advice would be to let the install company try and sort it, you never know they might have learnt something in a year...

 

[davey_b]

Well, you have had lots of good advice there, but after seeing the pics, and reading all the advice, I do not think that optimisers are the answer for you, In certain circumstances they can be beneficial though.

Firstly, you need to get the two panels out of the shade, either move them or cut the trees, remember that those trees will grow so in 10 years they may shade 4 panels...
It looks like you have space to move 4, just a suggestion.

Also the install needs sorting, that silly bit of flex they have used will/can cause your inverter to go overvoltage, something that some companies do not understand, I think someone did the calcs and said you need 6mm which is always a safe size to use anyway for a domestic install.

I understand your frustration with all of this, but get the system sorted, properly, if it was working as it should you would be over the moon.

My advice would be to let the install company try and sort it, you never know they might have learnt something in a year...

The issue with the trees isn't that they shade all day rather they shade all the panels in the morning and then the panels start to come into sun about 11am and then by 2pm all the panels are in full sun. Thus from my understanding optimisers would help as they would allow us to generate an increasing amount between 11am and 2pm. Sound correct?

Re the white AC cable from the inverter to the generation meter. I measured it this morning and it's 1cm (10mm) in diameter. That's the whole cable including the white insulation. Thus I wonder if the cores are 1.5mm or 2mm at the most? It's a round cable. Thus do you think this is most likely to be the cause of the "Vac 10 min too high" error or "Frequency too high" that was causing the inverter to shut down?

Thanks

 

[The Solar King]

If you examine the white cable carefully, it should be embossed at regular intervals along its length with its specification. Incidentally, has this been routed internally or externally to reach your consumer unit? (fuse box). From your description it is unlikely to be more than 2.5mm. We have never fitted Solarmax, so cannot comment on their error messages.

The issue with shading needs to be modelled and calculated to estimate what the reduction in annual output is compared with no shading. This alters from month to month with the tilt of the earth. The system should be modelled without and with optimisers to see what level of gain could be expected. If the gain is not great enough, they would not be a viable option.

Incidentally, in terms of resolving this, from the description of your property, do you have an unshaded West facing roof? It is possible relocating the array could provide better output than its current location.

 

[davey_b]

I'll have a look at the cable tonight. It is routed internally in the loft and then out along under the soffit outside and then back into the house.

We do have a west facing roof but there isn't enough room on it to fit the panels. I do wonder if we could fit 2 panels on the other side of the thermal panels and then 2 under the thermal panels in landscape.

Here's a better picture of the roof taken in April at 1.23pm

 

[SolarCity]

The amount of shading on that roof is immense. How far does that tree line to the right hand side of the picture extend?

Did your installer mention how much of an affect this would have?

 

[The Solar King]

It is not just the tree line. Look at how the land slopes up as well altering the horizon point. Even without trees there would be shading issues until the sun was well up in the sky. This was one of the reasons for mentioning relocation. It would also start to explain why the solar thermal array is so big.

 

[SRE]

We're pretty cautious and I have to say we've recommended customers don't install in this situation before. Admittedly it was before micro-inverters and optimisers were around and the cost of the array was substantially more.

 

[Earthstore]

The issue with the trees isn't that they shade all day rather they shade all the panels in the morning and then the panels start to come into sun about 11am and then by 2pm all the panels are in full sun. Thus from my understanding optimisers would help as they would allow us to generate an increasing amount between 11am and 2pm. Sound correct?

Re the white AC cable from the inverter to the generation meter. I measured it this morning and it's 1cm (10mm) in diameter. That's the whole cable including the white insulation. Thus I wonder if the cores are 1.5mm or 2mm at the most? It's a round cable. Thus do you think this is most likely to be the cause of the "Vac 10 min too high" error or "Frequency too high" that was causing the inverter to shut down?

Thanks

So, you are losing about 50% of max production per day in the summer, it will be worse in the winter as the sun is lower in the sky, therefore shading more panels.

It is highly probable that the "flex" they have used is causing the error codes mentioned, due to voltage drop.
I will try and explain, let's assume that your incoming voltage is on the high side, say, 250V, and at full power the Volt drop is 15V down your "flex", then for your inverter to match the mains voltage (well it has to go slightly over to push your PV power back into the grid), your inverter will have to raise it's voltage to 265V+, therefore exceeding it's set parameters causing it to produce the said fault codes.
This is just an example, and with some facts all of this can be calculated, but I hope this example gives you the understanding that you need.

Also, a little more technical this, your inverter may well be working on a particular input range from your panels, then when the shading clears, sometimes quickly, your inverter is still looking on or around the original power curve, which, may well be a long way from what your unshaded panels are now producing, not only can this cause some of your low output, it may cause a fault code too.

SMA inverters for example, have a setting called optitrac, which if enabled checks a wide range of input power curves to find the correct one for optimum output, some other makes of inverters have similar systems too.

As I have put before, all of your problems can be rectified, it is just a shame that you choose the company that you did to install your system.

Have you contacted them yet? If so what reply have they given you?

 

[davey_b]

Not contacted installer yet as the manager is away this week but I have an email drafted.

Flex from the inverter to ac isolator is twin and earth 2 x 4mm and 1 x 1.5mm. White cable to generation meter is 2.5mm

 

[provr6]

The shading you have shown in your pic is similar to mine until about 11am when I get full sun on all panels. My generation is not impacted anywhere nearly as severe as yours. I have a sma3600 twin inverter which uses optitrac for shading issues.

I would certainly be getting the installer back if poss to see if they can be shifted along out of the shade or ask him to change the inverter. Your system as it stands would probably generate more if you removed the 2 shaded panels altogether ( I know thats not the point as you have paid good money for them).

 

[davey_b]

Your system as it stands would probably generate more if you removed the 2 shaded panels altogether ( I know thats not the point as you have paid good money for them).

Or if they fitted optimisers at least the panels in sun would be able to generate at full power without being held back by a wee bit of shade.

 

[provr6]

Or if they fitted optimisers at least the panels in sun would be able to generate at full power without being held back by a wee bit of shade.

Quite possibly. They are new to me and guess they are a bit like micro inverters. I'm interested in these myself. Are they fitted to just panels that are shaded or to all panels?

Are we talking a lot of money to install to say just 2 panels. Could be a good option if not too expensive.

 

[Worcester]

Good optimisers (SolarEdge) work down to about 5V input from the panel. ALL microinverters have a fairly narrow range of acceptable input voltage, on an average 30V poly panel, every micro-inverter available in the UK will drop below their minimum input voltage as soon as one bypass diode kicks in - voltage now down to 20V, the micro-inverter shuts down, consider two diodes now down to 10V, higher voltage output mono panels, then some micro-inverters (notable Power-One) will cope with one diode kicking in.

Net effect, micro-inverters could well be less effective than a well designed string system - e.g. SMA's optitrac.

Optimisers e.g. Solar Edge which can easily be retro-fitted to an existing inverter - they have one specifically for these purposes (I can't comment on Tigo, excpet that their voltage range is much lower than the SolarEdge) should therefore give a better output than a micro-inverter installation.

You have to fit an optimiser to each panel and they also need a central controller that sits between them and the the inverter. The central controller can them link up to on-line monitoring that can give you panel by panel output information. (Yes I know some of the panels are shaded hence the lowere outputs )


p.s. there are 4 different makes of panel in the above set up with SolarEdge optimisers.

 

[methley]

Here's a slightly clearer picture of what SolarEdge can do. Here we have an east, south and west facing panels all on the same system being optimised by SolarEdge.



And again here, an array of 5 panels which are hard shaded by an adjacent ridge casting a decreasing diagonal shadow over them. Each panel comes on-line as soon as the shading disappears whilst not affect yield from the other panels.

 

[davey_b]

Looking at the SMA sunny boy inverters. They seem to do a pretty good job of dealing with shade. Anyone got any idea of the difference between replacing our solarmax inverter with one of these as opposed to leaving solarmax inverter and putting in solar optimisers?

Thanks

 

[The Solar King]

If you are going to change inverter and are considering optimisers, it will be more cost effective to use Solar Edge. The Solar Edge inverter is designed for use with their optimisers. Retrofit optimisers (solar edge or tyco) will be a more expensive option, as each one is more expensive. Using a complete solar edge system gives the kind of monitoring capabilities shown in the last two posts.

Panels could also be placed on different faces of your building if this would maximise potential output.

A properly designed system using optimisers should give better performance than one without. However, this has to be judged against the incremental cost.

 

[davey_b]

I'm just thinking about options and wondering if fitting an inverter with technology to deal with shade would give us nearly as good performance with a lot less hassle and expense?

The panels can't go on any other roof so we're stuck where they are.

 

[ExtremePV]

For the simplest option I would certainly recommend changing the inverter for a SunnyBoy 3600TL.
If you enable OptiTrac (disabled by default) it really does an amazing job dealing with shade.
If you know how the strings are configured then it should be a simple inverter swap.

Ken

 

[davey_b]

For the simplest option I would certainly recommend changing the inverter for a SunnyBoy 3600TL.
If you enable OptiTrac (disabled by default) it really does an amazing job dealing with shade.
If you know how the strings are configured then it should be a simple inverter swap.

Ken

Yeah that's what I was thinking. I emailed the installer yesterday giving them 3 options

1. Install optimisers
2. Install microinverters
3. Remove and refund

However, I'm not thinking there is a 4th that is easier and that is install a SunnyBoy inverter.

I'll see what they say when they come back to me.

What you do you mean when you say "if you know how the strings are configured"?

Cheers

 

[ExtremePV]

I'm assuming that the panels are configured in 2 equal length strings. i.e. something like top 8 as one string and bottom 8 are the other.
The SB3600 has two separate MPPT inputs, so can deal with different length strings. It 'may' be worth reconfiguring the strings so that one string is never shaded, and the other string deals with the shaded panels. I haven't run a simulation to see which is best (any real world experiences welcome)
Personally I would swap the inverter out for a SunnyBoy with the existing string configuration, enable OptiTrac and let it run and log some data. You can then see exactly how each string is performing, and then make an informed decision if its worth adjusting the stings.

 

[provr6]

Changing inverters would be the least hassle in my opinion. The sma 3600 can be considered as being 2 separate inverters. I would look into having as few panels as possible on one tracker and include both shaded panels on this tracker (within the limits of the inverter). The remaining panels can go on the other tracker and produce max'm generation as they won't have any shade at all pulling them down. You don't have to have equal No of panels in each tracker but you do need to check the min'm start up voltage and the max'm No. of panels each tracker can take.

 

[davey_b]

The panels are in full shade in the morning and then come into sun from the left to right as the sun moves around. Thus they all get some shading at some point in the day and the ones on the left get out of shade earliest.

Bearing this in mind and what you've said I wonder then if it would be best to have the 8 on the left hand side in 1 string and the 8 on the right in a second string and put them on an SMA inverter with optitrac switched on for both.

Looking at what people are saying about optitrac it seems to be pretty good and I think it might give us the best possible output from these panels in this location (the only location they can go).

 

[Worcester]

We have two arrays here, one with solaredge inverter and optimisers and one with an SMA TL inverter spilt into strings designed to minimise the effect of shading on the array as a whole (i.e one string connected to one of the MPP's gets 'hit' the worst) with optitrac enabled, both get very similar shade. To the annoyance of solar edge, it is very difficult to tell the difference... (there are other technical reasons for installing one of the arrays with solaredge)

 

[davey_b]

We have two arrays here, one with solaredge inverter and optimisers and one with an SMA TL inverter spilt into strings designed to minimise the effect of shading on the array as a whole (i.e one string connected to one of the MPP's gets 'hit' the worst) with optitrac enabled, both get very similar shade. To the annoyance of solar edge, it is very difficult to tell the difference... (there are other technical reasons for installing one of the arrays with solaredge)

Well there we go. It seems that the most straightforward, easiest and cheapest option is fit sma inverter.

 

[Worcester]

Possibly, though you will also want to sort it out into strings that get the worst / best shade / sun.

You should also have a string test doen to see if there are any faulty panels / miss wired strings, your current inverter may have two strings (and one MPP tracker) thouh how have they been physically wired? You want to put all the worst affected panels into just one string, so that will at a minmum mean a good crawl on the roof and look under the panels to see if you can see how they've done it. Most likely it will mean taking at least half the panels off and re-wiring them in the best order. So whilst you've got them off.... what would the cost of optimisers and control box be vs a new inverter...... probably very similar, though the latter may be less actual work.

 

[davey_b]

Possibly, though you will also want to sort it out into strings that get the worst / best shade / sun.

You should also have a string test doen to see if there are any faulty panels / miss wired strings, your current inverter may have two strings (and one MPP tracker) thouh how have they been physically wired? You want to put all the worst affected panels into just one string, so that will at a minmum mean a good crawl on the roof and look under the panels to see if you can see how they've done it. Most likely it will mean taking at least half the panels off and re-wiring them in the best order. So whilst you've got them off.... what would the cost of optimisers and control box be vs a new inverter...... probably very similar, though the latter may be less actual work.

I'm thinking more for the installer as I expect them to come and do this and pay for it. They could reuse my solarmax inverter on another job that has no shading and give me an SMA one that works with shading. Cheapest option for them by a mile.

 

[Worcester]

The regulations say that they can't re-use equipment defined as panels and inverters that have been once installed on a FiT registered installation on another one. One questions their competence to make any sensible decision or recommendation though, and I wouldn't be suporised if they tried to do that to the detriment of someone else....

Where are you with the conversation with your installer and what have they offered to do so far?

You have all the advice, it's now time to get it resolved...

 

[davey_b]

Emailed them yesterday but the manager is off this week so we'll see what comes next week.

 

[Gavin A]

Well there we go. It seems that the most straightforward, easiest and cheapest option is fit sma inverter.

Aurora Power One have the exact same shading functionality and dual MPPT set up, but for a fair bit less money.

Attached is one we installed earlier, with hard shading from next door house coming across the array from 5.40pm. full scan function set to 5 minute intervals on Aurora power one 3.6 Out-D, as the performance at 15 minute intervals was terrible, and I've approximated the shaded and unshaded production lines for comparison. The shading actually happens almost exactly as per our model, as does the performance.

btw can I ask, how did you end up choosing this company to install your system? This sort of situation is the entire reason that this recent race to the bottom with solar is a really bad idea,along with the get 3 quotes mantra - getting 3 quotes is all very well if people go with the best company, but far too often they're just going with the cheapest and assuming that solar is just simple technology / ignoring the benefits of going with an experienced well trained installer even if it might cost a little extra up front.... or often actually, people end up buying from some smarmy sales person who knows nothing about solar, then wondering why it doesn't all work out well for them.

Let this thread be a warning to others, if you buy from a company who doesn't know what they're doing, then it can all go very badly wrong for you especially where there is any shading involved.

I do hope you get this sorted, but at the same time, I can't help but feel that maybe you contributed to this by choosing a company that didn't know what they're doing for some reason, then expecting the experienced installers on here to assist you for free down the line when it's all gone wrong - the same experienced installers who're being undercut by the sorts of idiots you got to install for you.

Apologies if you think this is out of order, but I have had an ale and am going to get on my soapbox for a minute, as this is a serious issue for the industry and our customers and potential customers.

It's an example of why cheap / big but know nothing companies aren't always best. We recently took someone on who'd been British Gas trained for solar and worked for them for 18 months, then worked for another company, so total 2.5 years solar experience, mainly with SMA.... he'd never been shown how to set up the optitrac global peak shading function on their inverters, or even told that it existed.

As a counter point to that, we trained our guys in it within a few days of it being released, and bought laptops specifically for them to use to set this up, and went back to upgrade a lot of customers inverters with the updated firmware within weeks, which really is the difference between a highly specialist company, and some fly by night, or big company that's decided to move into solar.

If you have shading, then please find a company that really knows their stuff to deal with, otherwise this sort of situation will very likely be the result. Solar is not simple, it can not be learnt properly via a 3 day course led by trainers who've only done a couple of installs themselves, or have competence properly assessed by assessors who've only done 5 installers themselves.... unfortunately that makes up much of the industry, and is all the MCS requires, so as a customer if you have a complex install you really need to make a judgement about whether the installer seems to know what they're talking about or not.

tbh this is more of an indictment of the industry regulators than anything, unfortunately the public get misled into thinking that all MCS companies must know what they're doing, when the reality is very different - MCS is no guarantee of quality or competence, it's basically a minimum standard, and you're left to assess for yourself whether the company actually knows their stuff beyond that bare minimum standard.

I hope you get this sorted though, as far as it's possible to be sorted.

 

[davey_b]

Totally fair points there.

I was of course fairly influenced by price but I checked the company out and spoke to previous clients. To be fair to them they've not yet had a right to reply so we'll see what their response is.

 

[davey_b]

Had the guy out today and to be fair to him he was really decent and is keen to get this sorted. He's said we can have a different inverter and has said sma sunny boy and aurora power one both have technology to deal with shading. I think sma has software to track the global peak whereas aurora has 2 mppt.

So the question is which one is best to go for? Any thoughts?

 

[telectrix]

i'd be buying one of these babies.

 

[Worcester]

Power-one also has software to specifically cope with shading across multipel strings. As with the SMA inverter, you have to specifically switch it on.
Power-one on-screen configuration, SMA via the sunny explorer software. In your case, I would slo check that the installler has the knowledge as to how to do this - or even if they know that the functions exists beyond the twin MPPT. Additionally with Power-One you can manually change the re-scan interval time to check it has the best value (it time it scans the output will be affected as it searches for the best value)

Horses for courses. We've installed both!

SMA has easier and better monitoring built in and with Sunny Explorer on your PC, the display and ability to store detailed output is 'free' (you DO NOT need a 'SunnyBeam) Add in some extra free software and you could have a live link to PVoutput.org as well. Power-one is a little more complicated.