low output until all panels in sun

davey_b · Jun 12, 2013

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 · Jun 12, 2013

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 · Jun 12, 2013

provr6 said:
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 · Jun 12, 2013

davey_b said:
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 · Jun 12, 2013

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

)

[ElectriciansForums.net] low output until all panels in sun

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

methley · Jun 13, 2013

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 · Jun 14, 2013

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 · Jun 14, 2013

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 · Jun 14, 2013

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 · Jun 14, 2013

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 · Jun 14, 2013

ExtremePV said:
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 · Jun 14, 2013

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 · Jun 14, 2013

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 · Jun 14, 2013

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 · Jun 14, 2013

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)

low output until all panels in sun

davey_b

provr6

davey_b

provr6

Worcester

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methley

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davey_b

The Solar King

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davey_b

ExtremePV

davey_b

ExtremePV

provr6

davey_b

Worcester

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