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