SB3600TL readings sound right?

[Glen Powell]

got 12kwh today 19 03 12 best yet. orignal inverter was sb 300tl which has just 1 mppt. so installer changed for sb3600. with dual tracker.
my ten panels are SE. 3 months from 6th dec produced 230 kw with sb 3000

Sorry unless you replied earlier that means nothing, 10 panels with sunny boy 3600, some ten panels systems have generated 16-20 kwh today as peak performances are now raising their heads again.

The inverters are called 3600, 3.6, 4400, 3000, 3.0 for a reason. this is when they work at its optimum you will see efficiency % drops as the input voltage and current are lower than the optimum.

I have been a member on this forum for a very, very short time and already I see people quizzing the people within the field and trying to big up a high efficient inverter on an overall low efficiency system.

Why did you need 2 MPPT if all on the same roof, shading? two different roof areas? or something totally different.

I am not having a go at you please understand, through this thread people have given good solid advice and I understand that people want to justify their purchase as a good one, but listen to the guys who do this for a living, there is a chance you will get you more return on your investment.

 

[provr6]

I've just used sunny designer.

Its come up with the following which I don 't fully understand.

1.The AC power of the planned single phase plant exceeds the specified unblanced load limits (3.69Kva). What does this mean? and what are the implications?
2. Inverter efficiency 92.3%. Is this good or bad?
3.Performance ratio 80.6%. Is this good or bad?

 

[Glen Powell]

I've just used sunny designer.

Its come up with the following which I don 't fully understand.

1.The AC power of the planned single phase plant exceeds the specified unblanced load limits (3.69Kva). What does this mean? and what are the implications?
2. Inverter efficiency 92.3%. Is this good or bad?
3.Performance ratio 80.6%. Is this good or bad?

I will have to do the SMA design myself to understand their software, I do not use SMA, but from what you say it is not good.

 

[Gavin A]

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.

Oversized is OK with 10% - 15% in some climates however we are in the UK so we need to think the other way, you could put a 2kw inverter on a 2.2kw array providing all other factors are in place i.e voltage range (taking into account temperature coefficiency), amps, wattage (other 2 should take care of that).

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

I really don't understand what you're on about.

SMA don't make any dual MPPT inverters with a lower rating than the 3600TL, and the main other dual MPPT inverter around is the aurora 3.6 out-d / 3600.

The alternative would be 2 separate small inverters, which I've just run through sunny design, and the best I can come up with from SMA is an SB1200 and 2000HF (8 panels being too high voltage for the 1200 or 1700), and the output for the 3600TL is 2160kWh vs 2118kWh for the 2 inverter option.

so yes the 3600TL is underpowered and nowhere near as efficient as it could be with a more optimally matched system, but it's still arguably the best option SMA make for this situation.

Now, maybe micro inverters or solar edge would have been an option, but I doubt the SMA helpline is going to be recommending them.

 

[Glen Powell]

Solar edge is not a good alternative at all, if SMA cannot produce a product that is suitably matched then another product should be sourced, power one, steca, and others can cope with these ranges.

 

[Gavin A]

Why did you need 2 MPPT if all on the same roof, shading? two different roof areas? or something totally different.

from his first post on the thread he's got SW / SE arrays.

so it's not surprising that his system's not generating as much as a perfect south facing system at this time of year. Must admit though that 5 panels sounds low for the minimum voltage range of the inverter, unless they're Sanyo N series or something.

 

[provr6]

I think there is also an Aurora Power one 3.0 which was what I was originally quoted on. I assume I was given the 3600TL because of the unavailability of the former.

In hindsight this may have been a better option, albeit still oversized but not as much.

 

[Glen Powell]

Sundown didnt post the first post ?? and he quite clearly said he has 10 panels facing SE in his last one I replied to.

 

[Glen Powell]

I think there is also an Aurora Power one 3.0 which was what I was originally quoted on. I assume I was given the 3600TL because of the unavailability of the former.

In hindsight this may have been a better option, albeit still oversized but not as much.

In my opinion this would be the most suited to your needs for a single string inverter with multiple mppt.

 

[Gavin A]

Solar edge is not a good alternative at all, if SMA cannot produce a product that is suitably matched then another product should be sourced, power one, steca, and others can cope with these ranges.

tbf, the power-one 3.0 Out-d would probably have been a marginally better choice, as on checking, it does have dual MPPT, but it's probably very marginal as it has 3.3kW max AC output vs 3.68kW for the 3600TL.

I still doubt the SMA helpline would have recommended the power-one inverter though.

 

[Gavin A]

Sundown didnt post the first post ?? and he quite clearly said he has 10 panels facing SE in his last one I replied to.

yes, but he did post HIS first post on the thread.

in the same situation as op.ie sb 3600tl 10 panels south west, 5 panels south east with chimney panels suntolight [ german] 2.5 watt.
we could check together . i live 30 miles north of london

 

[Glen Powell]

SMA minimum startup voltage 150v
Power one minimum start UP voltage 100v

The fact that the AC side is higher would make it more efficient

 

[Glen Powell]

And my post saying "sorry unless you replied earlier" meaning I did not go through all the posts again

 

[Glen Powell]

Before you say

voltage/temperature

yes I know voltage is not as important as current but with a small amount of panels it makes a massive difference

 

[Gavin A]

And my post saying "sorry unless you replied earlier" meaning I did not go through all the posts again

so you thought you'd just jump straight in and tell the guy his system was wrong. Interesting approach.

 

[provr6]

SMA minimum startup voltage 150v
Power one minimum start UP voltage 100v

The fact that the AC side is higher would make it more efficient

Do those min'm start up voltages matter, as surely both me and sundown easily exceed those?

 

[Glen Powell]

well if he has 5 panels SE facing then yes I would still jump in and say it is not really as good as it should be max ppt voltage on sanyo hit250 = about 175v (maximum)

 

[provr6]

well if he has 5 panels SE facing then yes I would still jump in and say it is not really as good as it should be max ppt voltage on sanyo hit250 = about 175v (maximum)

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?

 

[Glen Powell]

I am sorry for being too eager to try and help were help is not really neaded, I dont really like SMA and was trying to get you all to change inverters for one I was trying to sell you or give others the opportunity to sell you.

Minimum voltage has no bearing on this matter
Miniimum ampage or maximum ampage are useless
Conversion factors have no relevence at all
Coil sizes and losses are just buzzwords
Transistors have no place in an inverter

I am sure the installer installed exactly what was needed for you and those bringing my posts into question

 

[Glen Powell]

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?

2 mppt = 10 on one and 5 on the other