SB3600TL readings sound right?

[Glen Powell]

.hmmm really

 

[provr6]

You are obviously more knowledgeable than me and I wasn't criticising your advice. I was just stating advice received from my installer and putting it out there for those in the know to verify or rebuke.

On the contrary, I am grateful for your comments and all considered comments are welcome, even if it's not good news.

 

[Gavin A]

I see, but am I right in saying that the 10 panels on sundown's other roof would help meet the start up voltage? My installer said the start up voltage is based on the combined 2 roofs?

tbf to your installer, they were right about this when they'd first installed your system as they'd wired both arrays in series to the one MPPT input.

Now it's wired to the 2 separate MPPT inputs that's not the case, the voltage on each array is independent of the other.

 

[Glen Powell]

The basics of it is this

I am the technical director of 2 companies of which 1 deployed 500 installs in February, the inverter choice for your install would not have entered my design teams heads, if the designer of your system used any design software it would have probably spat it out and said no way or it would base it on the strong MPPT and give you a very poor efficiency rating.

In one of the sticky topics I have put a spread sheet up to help measure efficiency but you do need an irradiance meter (original thread goodwilld) on page 69 of the thread.

Be fully aware this is not my investment, this is really not my concern, but if your quarterly return is less than others you will not be happy. this is why I have given links to SMA software and their phone number. you can say you are going to install a system in this way and is it acceptable, take notes, get names, etc.

I will not loose 1 snippet of sleep tonight over this, if i am right or wrong is irrelevent which is why I say speak to the manufacturers.

 

[Glen Powell]

tbf to your installer, they were right about this when they'd first installed your system as they'd wired both arrays in series to the one MPPT input.

Now it's wired to the 2 separate MPPT inputs that's not the case, the voltage on each array is independent of the other.

Doesn't matter the underperformance of one will pull the other down, 101 solar design, the weak array will create resistance for the strong array if in series, if in parallel maybe a chance but not much as there is still an adverse effect.

 

[provr6]

tbf to your installer, they were right about this when they'd first installed your system as they'd wired both arrays in series to the one MPPT input.

Now it's wired to the 2 separate MPPT inputs that's not the case, the voltage on each array is independent of the other.

Thanks for that, I didn't realise that. It does make sense now as each MPPT is like a seperate inverter.

 

[Gavin A]

Doesn't matter the underperformance of one will pull the other down, 101 solar design, the weak array will create resistance for the strong array if in series, if in parallel maybe a chance but not much as there is still an adverse effect.

you appear to think I'm defending that method of installing, I'm obviously not.

I had previously read the posters previous thread where he was asking for help because their installer had originally done this, and was merely pointing out that on the original installation as it had all been run in one string, the installer wasn't lying when he told him (presumably at that point) that both arrays combined to produce the string voltage going into the inverter.

 

[Glen Powell]

Can we please put this to bed and put a poll on it would you or any other installer put either of the inverter mentioned on this guys array based on evidence given.

We are not here to rip each other just give honest opinions, simple yes or no answers would suffice.

NO

 

[Gavin A]

Personally in this situation I'd expect I'd have strongly recommended using the Sanyo N series 240Wp panels which would have given a system that was a much better match for the 3600TL (or aurora) due both to the increased array ratings, and the string voltage being closer to optimum.

but that wasn't the point I responded to. I specifically responded to this point

I would say by Quite a bit, however, you could get it from the horses mouth, did you run the software ?? or would it be better you speak directly to SMA about it, they will be able to tell you exactly how efficiently it will or will not work. I know what they are going to say.

SMA Telephone number is 01908 304850 , they may be a bit busy this week though...

Now I have run this though the SMA software, and the 3600TL is the most efficient option available from the SMA range for this panel set up as I pointed out clearly in my first reply to you 2 hours ago.

Not that I actually needed to run it as I work with SMA kit most of the time so know what the options are pretty well, which is why I took issue with your post.

 

[yorkshiremike]

I tried to post this yesterday, but it didn't work, presumably as it had an embedded results table from PVSOL:-

"Interesting enough, if you compare simulations in PVSOl for a SE (6 ET Solar panels), SW (8 panels) into a 3600TL (based on 4000TL as PVSOl doesn't have the 3600), a 3000TL-21 (new 2 tracker version of the 3000TL) and say a Power-One 3.0 (2 tracker) then the Power-one comes out about 2.5% ahead, but the 3600TL is the same as the 3000TL-20."

The feed-in figures from PVSOL (assuming London SE/SW at 31 degress incline) are respectively (3600, 3000TL-21 and Power-One): 2305, 2304, 2369kWh

As Gavin has previously stated, SMA design 'green ticks' the 3600TL on everything (startup voltage, mppt range etc), the only thing it questions is the oversize of the inverter. And the 3000TL-21 (twin MPPT which wasn't previously available) although it is within SMAs normal +/- 20% capacity range doesn't have any greater efficiency/yield.

 

[sundown]

thanks everone for their help. just to recap. ihave 10 panels SE and 5 SW.with chimney, after 2.30 pm when shade starts to overcome the 10 panels , the harvest becomes quite minimal .
the manufactures handbook quite clearly shows that a sb 3000tl , is not suitable for unequal strings . me thinks that why they invented dual mppt.
any way quite happy to have installed before dec deadline. latter i may remove chimney. or better still put it all out on new garage and get it due south