Suuny Boy inverter SB3000 HF-30

[PhilipK]

Hi - Can anyone help - I have a 3.67kw installation made up of 15 Sharp type ND-R245A5 panels in 2 strings ( 1 x 8 & 1 x 7 )
The inverter is a Sunny Boy SB3000 HF -30 which I was told was needed because of the uneven strings
Is this inverter powerfull enough to support a 3.67kw system as it seems never to produce above 2.9kw ?
Will it never achieve the annual 3.2 kw stated

 

[SolarCity]

Are you sure it is an SB3000 HF? If so, it only has a single MPPT and therefore it is not a good idea to have uneven strings connected to it.

 

[Earthstore]

What is tha orientation of the roof? south, east west split?
What is your location in the UK? what is the slope of your roof? (roughly in degrees)

 

[Gavin A]

Hi - Can anyone help - I have a 3.67kw installation made up of 15 Sharp type ND-R245A5 panels in 2 strings ( 1 x 8 & 1 x 7 )
The inverter is a Sunny Boy SB3000 HF -30 which I was told was needed because of the uneven strings
Is this inverter powerfull enough to support a 3.67kw system as it seems never to produce above 2.9kw ?
Will it never achieve the annual 3.2 kw stated

The only reason for using the 3000HF would be if it was run in single string, as the HF has a higher voltage range than most.

It's right at the top of the allowable input for the 3000HF, but that's not necessarily a bad thing, as the HF inverters are most efficient at high inputs, so while it will limit the output a little in full sun, it will probably generate more on average across the year.

Can you confirm how many of the PV cables you have going in to the bottom of the inverter - bottom left? Should be 2 cables if single string, 4 cables if 2 string.

 

[PhilipK]

Are you sure it is an SB3000 HF? If so, it only has a single MPPT and therefore it is not a good idea to have uneven strings connected to it.

Hi
Thanks for quick response.
It is definitely an SB3000 HF
Am I getting confused and it is not 2 strings but 1 and they had to use the HF because of 8 panels and 7 panels array

 

[PhilipK]

I have just checked and there are 2 cables going in the Inverter (bottom Left)
If it is 1 string did they have to use the HF because on uneven number of panels?

 

[whinmoor]

Could you provide a photo of the inverter? Do you have one or two DC isolators? They are normally grey on/off rotary-style switches. Especially interested in the connections at the bottom of the inverter and the wiring to the DC isolator(s).

Edit,

Just seen your post. Sounds like you have just the one string.

 

[PhilipK]

Hi
Roof orientation is south, rafter pitch 30, location is Stoke on Trent

 

[whinmoor]

Do all the panels face the same direction?

 

[SolarCity]

When you say that you have different strings, are they mounted on the same roof space? Or on a different roof space at a different orientation?

I would personally say that the 3000HF is not a bad choice for this array assuming that the panels are all at the same orientation. It may seem undersized but this is generally what installers do in the British climate - the basic understanding is that a 3000HF inverter will run better at, say, 2900w than a 3.6kW inverter - and that 2900w is far more common than 3.5kW. Does that make sense?

 

[PhilipK]

Hi
Tried to send photo but says to big

 

[whinmoor]

Email photo to me: [email protected]

I will post it for the guys to look at.

 

[PhilipK]

Same roof space - 1 row of 7 above a row of 8 all south facing on a roof with 30 degree pitch
I think I understand but will the gain by running better at 2900w outweigh the loss of never achieving above 3000w

 

[whinmoor]

Is there any shading from nearby buildings, trees, chimneys etc?

 

[PhilipK]

Yes - All south

 

[SolarCity]

Same roof space - 1 row of 7 above a row of 8 all south facing on a roof with 30 degree pitch
I think I understand but will the gain by running better at 2900w outweigh the loss of never achieving above 3000w

As far as my computer simulations go, it appears so.

 

[PhilipK]

No shading at all

 

[whinmoor]

Ok. Here's Philip's photo. Any comments? Looks pretty neat except for a possibly peeling label?
Looks like a single string as well.

 

[PhilipK]

Thanks that is good news.
However does this mean that the average annual system output will be less than the 3159 quoted and more like 2900

 

[whinmoor]

I'd expect your system to perform much better than 2900kWh per year. 3159kWh is the official Government SAP figure which tends to be rather pessimistic in my experience. You should do a bit better than that (assuming reasonable weather conditions of course).

I think your installer's done a decent job and hasn't "fiddled the figures".

You do have polycrystalline panels which are a bit less efficient than monos but they should work fine if installed correctly.

 

[Gavin A]

Thanks that is good news.
However does this mean that the average annual system output will be less than the 3159 quoted and more like 2900

no, I think you're getting mixed up.

the annual output is in kWh, whereas the limit on your inverter output is in kW.

They essentially are unrelated, though it roughly works out at around 8-900kWh per year per kWp of solar PV installed, which in this instance results in an annual output prediction of 3200kWh.

I'm not running this through sunny design as I've done this so many times I already know that the impact of the inverter being marginally lower rated than the peak output of the panels will result in losses of approximately 0.1-0.2% per year from the inverter capping the peak output, but the improved efficiency from running the inverter closer to it's peak efficiency point through the year should result in something like a 0.4-0.6% improvement in output, so the net effect is a marginally improved output.

3200kWh per year seems reasonable to me for a south facing system of this size, so I'd be reasonably confident that you should achieve this or thereabouts.

 

[tommac1]

That number of panels in one string would produce an over voltage for the 3000HF. You would have to wire for two strings to keep the voltage within the operational range. This can be done by wiring the two strings directly back to the two string inputs on the inverter (still only one MPPT though). Alternatively the two strings could be wired together with connecting sockets on the roof and a single connection will then go to the inverter. I believe that in either case that the two strings should be the same size, orientation shading etc.

 

[SolarCity]

That number of panels in one string would produce an over voltage for the 3000HF

Not by my calculations.....

 

[Gavin A]

Not by my calculations.....

or mine.

IMO it's actually pretty much perfect for getting the absolute peak efficiency from the inverter.

 

[moggy1968]

I think it takes underspeccing the inverter a bit far. I would have used a 3.6 inverter on this one

 

[SolarCity]

I think it takes underspeccing the inverter a bit far. I would have used a 3.6 inverter on this one

It's on the limit as far as I'm concerned. I generally go for 120% and no more. This is just personal choice though and until we get any solid empirical data from UK conditions then none of us are going to know for sure.

 

[dsa1000]

We recently installed 14x 245watt mono modules =3.4kw system using a SMA 3000HF, this was used by sma sunnyboy design am as best efficiancy and also for system, we installed it on one string with no shading and also a SSw roof at 39deg.

 

[dansk]

Im wondering if the OP is mixing up the "two rows" of panels as "two strings" because PV-SOL wont allow me to input two strings - also no over-voltage here even with VOC @-10 and 1000w/m² irradiance.

 

[MickF]

Ok. Here's Philip's photo. Any comments? Looks pretty neat except for a possibly peeling label?
Looks like a single string as well.

I thought that the DC and AC cables had to have physical seperation, looks like even if for a small distance they are in the same conduit.

Where's the emergency shutdown procedures?

Where's the Isolation stickers?

Where's the schematic?


Looks can be deceiving..

 

[moggy1968]

the emergency shutdown procedure has to be displayed at the point of interconnection, I.E the main fuse. I used to put it at the inverter as this seemed the obvious place, but got pinged for it on my previous inspection as the point of interconnection means between the suppliers side and the customers side, not the interconnection between AC and DC. HAving said that, could that flappy piece of paper be the shutdown procedure?

I think there are isolation stickers on there but it's hard to tell whats on them. The inverter should also have some stickers on it.

AC and DC should have physical seperation and I can't see how that would be achieved in this instance using the same piece of trunking, unless the cables go off in opposite (and rather unexpected!) directions.

It's not possible to tell if there are 2 strings from this, as there might be a connector bringing the 2 strings together further up the system. The best guide is probably the voltage readings because they will be about half what you would expect if it was one string.

 

[Gavin A]

tbf, I suspect the AC is going down, and the DC is going up in the conduit, so it's a relatively minor infraction of crossing the cables, and the inverter sticker looks like it's fallen off.

wiring diagram could be by the consumer unit, which'd be more sensible than the loft IMO.

Certainly far from the worst install I've seen pictures of

 

[moggy1968]

not sure if no seperation like that that would count as an observation or nonconformity, observation I suspect as you say it is probably just a cross over. Missing labels is an observation, as I know from my inspection today when stupidly I had missed one off!
The diagram has to be at the point of interconnection, which is the main fuse/meter position, which is often not where the DB is. I think thats because the diagram is regarded as for the use of the DNO.

But yes, none of these are major and overall it's a fairly tidy looking job, it's easy to nitpick!

 

[JulianC]

Re: AC & DC separation. Double insulated DC cable and insulated and sheathed flex or T/E is acceptable in the same bit of trunking is it not?

 

[moggy1968]

I actually can't see any refernce to physical seperation in 7671 or DTi Guide. It's one of those things we've always done, but now I'm thinking, do we have to worry about it!!

 

[SolarCity]

I actually can't see any refernce to physical seperation in 7671 or DTi Guide. It's one of those things we've always done, but now I'm thinking, do we have to worry about it!!

Likewise. I worried about induction from the AC cable but perhaps I'm worrying too much.

 

[Worcester]

Physical separation is a tick box on the commissioning report from the 2nd Edition guide, though which clause that comes directly from I have always been unable to trace! - As far as I am aware the only specific mention in the guide is the double ticked item 2.1.2 :

Double insulation (insulation comprising both basic & supplementary insulation, International Electrotechnical Vocabulary IEV 195-06-08), appropriate barriers and separation of parts must be applied to all systems with an open-circuit voltage of >120 Vd.c..

You might even be able to interpret that double insulated DC cables inherently achieve that requirement ....

Though it would be good practice anyway to keep them physically seperate, although the word and is important.