Sanyo HIT250's and SB4000TL

[seprim]

Hi
I am not yet MCS but I have C&G2372 and I am a little rusty , and have designed a system using currently available gear. The design is as follows;
16 Sanyo HIT250's
SB4000TL
Arranged in 2 strings of 8 modules in each string
Assumptions
1. My first assumption is that as its ≤4KW that it complies with FIT rules and as such would attract the highest rate, because 16 x 250Wp = 4KWp. . . .
2. Secondly that the PV panels and Inverter are compatible because in two seperate strings of 8 modules I have maximum DC voltage = Voc x 8 = 43.1 x 8 = 344.8v (which is a good deal less than the 550v stated as max for the inverter)
3. and that String mpp voltage for each of the strings is Vmpp x 8 = 34.9 x 8 = 279.2v which is less than the inverter max dc voltage and also, quite usefully i think - nearly half way between the min and max of the range given for the inverter's MPP voltage range (175v - 440v) mid way being 307.5v hence a difference of 307.5 - 279.2 = 28.3v [~10% out of dead centre]
4. also that the module Isc (7.74A) would show an array Isc of 15.48 A which is less than the maximum input current of 30A (2 strings of 15 A each)
5. peak power would be String mpp Voltage x Array mpp Current = 279.2v x 15.48A = 4,322.016 Watts . . and herein lies a dilemma - which do I use, Peak Power or Wp ?

Questions:
1. The SB4000TL has a maximum dc power of 4200W, yet my max output on a sunny winters day may well be 4322W . .. I was taught that generally the pv peak power is ~20% greater than the Inverter peak power. Would this design disqualify this installation from the ≤4KW FIT payment rate ? Would the DNO "have a baby" over this ?
2. Would I have to go G59/2-1 rather than G83/1-1 ? and would that alone disqualify the design from FIT ?
3. If i chose a different module, say HIT240's and the array peak power would be 3.85kW. Ignoring losses thats 16.75A put back into the grid. This is over the DNO stipulated maximum for G83/1-1 but less than the FIT repayment limit. . . would the DNO allow this arrangement ? Are they flexible ?
5. Has anyone had to do this to maximise the output and hence FIT for a customer ?
6. Why has the DNO stipulated a maximum in current (Amps) and the FIT's stipulated the maximum in power (Watts) ? Are they not singing from the same sheet ?

Andy
thx, and stay frosty

 

[Pv dude]

Hi
I am not yet MCS but I have C&G2372 and I am a little rusty , and have designed a system using currently available gear. The design is as follows;
16 Sanyo HIT250's
SB4000TL
Arranged in 2 strings of 8 modules in each string
Assumptions
1. My first assumption is that as its ≤4KW that it complies with FIT rules and as such would attract the highest rate, because 16 x 250Wp = 4KWp. . . .
2. Secondly that the PV panels and Inverter are compatible because in two seperate strings of 8 modules I have maximum DC voltage = Voc x 8 = 43.1 x 8 = 344.8v (which is a good deal less than the 550v stated as max for the inverter)
3. and that String mpp voltage for each of the strings is Vmpp x 8 = 34.9 x 8 = 279.2v which is less than the inverter max dc voltage and also, quite usefully i think - nearly half way between the min and max of the range given for the inverter's MPP voltage range (175v - 440v) mid way being 307.5v hence a difference of 307.5 - 279.2 = 28.3v [~10% out of dead centre]
4. also that the module Isc (7.74A) would show an array Isc of 15.48 A which is less than the maximum input current of 30A (2 strings of 15 A each)
5. peak power would be String mpp Voltage x Array mpp Current = 279.2v x 15.48A = 4,322.016 Watts . . and herein lies a dilemma - which do I use, Peak Power or Wp ?

Questions:
1. The SB4000TL has a maximum dc power of 4200W, yet my max output on a sunny winters day may well be 4322W . .. I was taught that generally the pv peak power is ~20% greater than the Inverter peak power. Would this design disqualify this installation from the ≤4KW FIT payment rate ? Would the DNO "have a baby" over this ?
2. Would I have to go G59/2-1 rather than G83/1-1 ? and would that alone disqualify the design from FIT ?
3. If i chose a different module, say HIT240's and the array peak power would be 3.85kW. Ignoring losses thats 16.75A put back into the grid. This is over the DNO stipulated maximum for G83/1-1 but less than the FIT repayment limit. . . would the DNO allow this arrangement ? Are they flexible ?
5. Has anyone had to do this to maximise the output and hence FIT for a customer ?
6. Why has the DNO stipulated a maximum in current (Amps) and the FIT's stipulated the maximum in power (Watts) ? Are they not singing from the same sheet ?

Andy
thx, and stay frosty

Run it through SMA free software its very easy to use and effective.

 

[seprim]

Hi
I have been in touch with my DNO (UK PowerNetworks) and been sent some useful info, clarifying a whole load of stuff that I have asked in this post. It didn't answer all my questions but I must give my brain some time to absorb the info and apply common sense to it
Here goes;
Assumptions:
My first assumption that the DNO is interested in the DC output of the panels is false. They are only interested in the AC output of the system. To comply with G83/1-1 this must not exceed 16 amps @ 240volts (yes 240) = 3.86kW. - read on . . .

calculations assumptions - no further info qualifying or denying these calculations
Is Wp peak power ? No - Peak power according to the DNO is the “AC output” = no. modules x Wp x efficiency of inverter = 16 x 250 x 97% = 3.88kW so this arrangement would not be acceptable for G83/1-1 according to this DNO.
NOTE: if I used HIT245's instead of HIT250's then the “AC output” would be as follows – 16 x 245 x 97% = 3.8024kW which is below the 3.86kW threshold and hence acceptable to this DNO for G83/1-1.

Questions:
Essentially I think the question here is . . can I use an SB4000TL ? And the answer is yes, you can, according to this DNO (at least they have no problems with it) because it has a G83 Compliance Certificate, and;
The DNO require you to compare the AC output of the system with the rated output of the inverter, and then use the smaller of the two.
e.g. SB4000TL rated AC output = 4000W and if the max AC output from the array and inverter is 3.8024kW (if HIT245's are used). One would use 3.8024kW (the lesser of two weevils).
So would this design (originally 16 no. HIT250's and an SB400TL) disqualify this installation from the ≤4KW FIT payment rate ? - No
Would the DNO "have a baby" over this ? - No because for this DNO, one would have to apply for permission to connect a 3.84kW ≤ Output ≤ 4kW generation, making it plain that it is for a single installation, and it must be accompanied by a location map.
No G59 is required with this design and No it wouldn't disqualify from FIT (with this DNO)
Could I use HIT240's – Yes. NOTE When applying for permission it is advisable that one applies as soon as possible as commissioning depends on permission and this may take some time . . . .Could the DNO refuse permission in some areas ? Yes . .perhaps, but I don't know for sure.

Has anyone had to do this ? The question remains. .

Why has the DNO stipulated a maximum in current (Amps) and the FIT's stipulated the maximum in power (Watts) ? - Still don't know that one
My Caveat would be - if you have a 3.84kW ≤ Output ≤ 4kW SSEG design and you want to know if you can install it - contact your DNO first
Regards

Andrew - stay frosty

 

[a62vw]

Hi Andrew,
Thanks for this really useful post; I'm in exactly the same situation - 1st PV install since training in April, same proposed system config and same DNO (I'm in Mid Sussex, nr East Grinstead) so this stuff is a god send for me!
BTW, where are you getting your kit from? Been spending a lot of time doing a lot of research on suitable trade suppliers.
Have you done the install yet? Would be interested to know how it went!
Cheers,
Vaughn.

 

[seprim]

Hi Vaughn
I am in the process of doing my first install. I got a kit from CEF, although if you search on "suppliers" in this forum you will get lots of company details as well as feedback on their performance from individuals experiences. The install took me a week on my jack and as I was new to roofs i went pretty carefully. (also cos i weigh 18 stone and could have broken all the tiles but i only eventually broke 6)
I have my inspection soon (although no date confirmed yet as I am sorting out the QMS right now) I will let you know how it went
Andrew :ninja:

 

[a62vw]

Thanks for the update, and good luck with the inspection! Hope it goes well!
How are you doing your QMS - r u going thro EasyMCS or something similar?

 

[yellowvanman]

Shouldn't you be using 230V for all your ac power calculations?

 

[Graeme Harrold]

This is where the confusion starts 230, or 240. Unfortunately you are at the mercy of the DNO as to what they will accept. Been talking to SPN who basically said they were fed up waiting for clarification on the matter and have set their own rules.

Done a couple of SMA 4000TL's and had to complete a G83 stage 2 application and have not had a problem yet. The guide does state to get in touch with your DNO early in the process..........best to get them onside from day 1....

As to the installs, all I had to do was shift the frequence cut out to 51.5Hz at 5 secs. You will need to contact SMA to get your Gridguard access code to modify the settings though. I then had to take a screen shot ( Sunny Explorer) showing the changes to be submitted as part of the connection confirmation.

 

[seprim]

Hi yellowvanman - that was my first thought but the DNO specifically said 16A @ 240V, so I asked "are you sure" and the DNO said yes absolutely so.
I quote
"The first point to note is that G83 has a fixed upper limit of 16 Amps per phase at 240 Volts (3.84kW), which doesn't quite extend to the 4kW of the first band of the Feed-In Tariff. However, many installers, in talking to customers, who want to hear a big number, refer to the size of the installation according to the DC output of the Solar Panels, whereas we as a Distribution Network Operator, are concerned with the AC Output from the inverter. Please see the explanation below on how to calculate the output to record on the G83 form.
Calculation of the size of the SSEG
Some installers appeared to mis-understand the rating of the SSEG as it should be reported on the G83 form. What is required is the maximum output from the SSEG, not the total rating of the solar panels. The calculation should be done, as follows:
Add the total rating of all of the solar panels. Call this SP_Rating.
Identify the efficiency of the inverter. Some inverters have charts showing how the efficiency varies with the DC Input Voltage, and other factors, and some just state an 'Average Efficiency'. Call this Inverter_Efficiency.
Multiply the two figures (i.e. SP_Rating x Inverter_Efficiency). Call this Output_1.
Compare Output_1 with the maximum rated output of the Inverter. Take the smaller figure. This is the SSEG output which should be reported.
Consider the following worked example:
7 solar panels rated at 235 Watts each, with a Sunny Boy 1200, (rated at 1200 Watts)
7 x 235 = 1645 Watts (SP_Rating)
Inverter Efficiency = 92% (Inverter_Efficiency).
SP_Rating x Inverter_Efficiency = Output_1.
1645 x 92% = 1513.4 Watts (Output_1)
Compare Output_1 (1513.4 Watts) with the rated output of the Sunny Boy 1200 (1200 Watts), and take the smaller figure, which is 1200 Watts.

Generation up to 3.84kW Per Phase
You need to note that G83 allows for up to 16 Amps per phase at 240V AC (i.e. 3.84kW), and there is no flexibility to exceed 16 Amps per phase under G83.

Submitting G83 Notifications
The G83 form needs to be accompanied by a copy of the G83 Compliance certificate of the Inverter and a Schematic Diagram of the installation.
Our preferred method of receiving G83 registrations is by email to the address on the form. When G83 Registrations are made by email, it is sufficient to type your name as your signature.

MPANs
A key item of information for the registration is the MPAN, which is on the Customer's electricity bill. Experienced installers collect this information when the customer places the order.
There is a useful webpage to identify the DNO from the MPAN at:
Meter Point Administration Number - Wikipedia, the free encyclopedia

Generation between 3.84kW and 4.00kW Per Phase
If you are considering an installation which is between 3.84 and 4kW, then you will need to Apply for permission to connect this generation. Please complete our G83 Application form, making plain that this is for a single installation, and send it to the email address or the Fax number:
Email: [email protected] Fax: 08456 500248
The Application from is available at:
http://www.ukpowernetworks.co.uk/pr...83_multiple_installation_application_form.doc
The application needs to be accompanied by a Location Map.

Larger Generation
For larger generation, please contact me again for guidance on how to connect generation which is in excess of 4kW per phase."
. . .end quote
It doesnt explain why they still use 240V as opposed to 230V but the other info may be useful.
regards

Andrew

 

[Stoneboy]

Hi
You best apply for a grid guard code from SMA so that you can set the Pmax limit to 3.68 so that it wont output more then the 16A under G83

good luck