3680W DNO Limit affecting System Choice

[MattyKHZ]

Having room for 16 south facing panels I got hung up on efficiencies and started to look at 16 of the Sanyo HIT-N240SE10 panel making a 3.84KW system.

I was recommended for similar money to go for 17 of the HIT-N235SE10 panel as this would be 3.95KW.

Yet from a configuration point of view 16 panels would look best so even though less efficient I decided on 16 of the older 250W Sanyo HIT panel.

Inverter was going to be the SMA 4000TL but I hear that you have to restrict to 16A or get DNO permission.

Just wondering why people would go for larger than 3680W output if you cannot use it or get FIT for it if the DNO will not accept it? Or is it a question of time and if the FIT changes were not rushing things you would be able to apply for running more?

As time is of the essence and say if I can get the Sanyo in 250W panel, would I be better with the 4000TL or maybe the Solar Edge SE4000 system and power optimisers. Would teh 4000TL not get approved by the DNO or take too long to? I guess it depends on the area I live in (Tamworth) and how many existing installs there are in the area.

If the efficiency and power optimisers in the Solar Edge system are beneficial is the extra expense justified if again you are restricted to 3680W. Why do people go for 4KW if you cannot link it to the grid at full capacity?

It seems to me that you would be paying extra for generation capacity that you cannot use!!!!

 

[langstroth2]

Just wondering why people would go for larger than 3680W output if you cannot use it or get FIT for it if the DNO will not accept it?

DNO will often accept it - but install takes longer as DNO has to say yes prior to install (G59). Time that probably isn't available in the current deadline rush

A 4kw system not limited to 16A will therefore be able to export more. However in reality this is likely to only occur a few times in the year when the panels are still cool, but the sun/irradiation is high. I've not done any calcs but I would doubt it amounts to much in the way of "lost" revenue due to limiting.

The real reason people go for the 4kw is simply to maximise output for any given irradiance. i.e 4Kw should produce more output per day (albeit with a peak probably generally well under 3.68Kw) compared with a 3.68Kw system all other things being equal (which they never are....)

 

[MattyKHZ]

Thanks.

So really if I am deciding between a 4000TL inverter and a Solar Edge SE4000 with Power Optmisers I would be wasting money on the Solar Edge system as if both are restricted to 16A they would produce the same amount of power.

With the Solar Edge only helping if ever there were shading issues.

 

[Earthstore]

KWP is different to KWH.
KWP is the maximum a system would produce without any losses.
KWH is power actually produced.
Therefore if you take into account, cable and inverter losses, orientation and pitch of roof, shading if any, a 4 KWP system would never produce 4KW, and to be honest would probably never "peak" at 3.68 KW.
The DNO (District Network Operator) will accept without prior approval, an inverter that is G83 approved, which has its maximum output restricted to 3.68KW.
You will also have to get your skates on if you are trying to beat the 12th December deadline for the FIT reduction, remember the system has to be installed, commissioned, and your energy provider has to be in receipt of your FIT registration form with out any mistakes.
I am now selling systems (SMA, Suntech and Tritec mounting)for the new tariff only, and with price reductions can offer returns of 9.5%-10% returns.

 

[MattyKHZ]

OK so it just seems that I have to weigh up whether or not the £400 to £500 extra Solar Edge costs is worth it for the individual moitoring and performance capabilities per panel rather than per string. Over the 25 years it may prove worth it.

I was in a position to order last week but was messed around by some companies who would not do a tech survey until the day of fitment meaning no issues could be dealt with prior to that. This killed the deal for me as I knew more than the salesperson and specific question amount mountin, electrics and CU were ignored and I was simply being chased for a deposit.

Luckily I am on the waiting list to pay my deposit for November install with no money being accepted until all supplies are confirmed which I think is reasonable given the current circumstances.

It seems many are putting their prices up for install before the 12th Dec or contacting with reduced prices for install after the 12th Dec.

It does seem that those with stocks or availability are fleecing customers to get the most per install prior to the 12th Dec and then will be going around cap in hand after trying to win business at new improved rates. I have been told that prices will be 25% less by some but if FIT is reduced by 50% then a 25% reduction in install is not as good as getting it done now.

 

[Earthstore]

it


"Luckily I am on the waiting list to pay my deposit for November install with no money being accepted until all supplies are confirmed which I think is reaosnable given the current circumstances."

So you will miss the December 12th deadline then?

 

[MattyKHZ]

Not really if it is a November install.

 

[Earthstore]

Sorry my mistake, one thing to check, which may help you, If you go on to the MCS website, click on find an installer, then put any company in that has quoted you, you can find out when they fitted their first job.
I am in sales, and whilst with a customer on saturday a company rang and were persistent to try and get an order, they had been trading for one month.
I would not give £1000's of pounds to a company, in these difficult times that had only been trading a month!!
Hope this helps.

 

[MattyKHZ]

Thanks.

The one in question who was chasing me was registered in September. It is something that concerns me as many may not be around after Dec 12th. Despite offers of 20 year Inverter warranties, REIGA etc.

At the end of the day I have narrowed down my choice through the good advice on these forums for panels and inverters. When sales people do not really know waht will happen on the day it does not enstil me with confidence and many seem to be rushing and risking a bodged job than getting correct answers prior to an install.

It has been eye opening having all these meetings and surveys. Hopefully supplies check out and my order is safe, if not, I will have to re-evaluate at newer prices related to the change in tariff and certainly won't have a knee jerk reaction to not getting an install prior to 12th Dec if it does not pan out for me.

 

[Earthstore]

The Sanyo's are a good performing panel, although the manufacturing process is not so green, However you can get more kw per £ if you use a Suntech.
It all depends on your personal reasons for installing a system.

Personally I am more concerned on how the panels are actually fitted to the roof and quality of install, than a .0001 difference in panel performance.

If, and I am sure it will happen this winter, somebodies panels end up in a smashed heap on their drive, it would not matter what type they were.

I was distraught when the FIT news was announced, however now the dust is settling I believe it will sort the "wheat from the chaff".

I hope all goes well for you, if I can help at all in the future please mail me on
[email protected]

 

[pwboston]

Sorry my mistake, one thing to check, which may help you, If you go on to the MCS website, click on find an installer, then put any company in that has quoted you, you can find out when they fitted their first job.
I am in sales, and whilst with a customer on saturday a company rang and were persistent to try and get an order, they had been trading for one month.
I would not give £1000's of pounds to a company, in these difficult times that had only been trading a month!!
Hope this helps.

Thats only half the story in my view and not to be taken fully, for instance we are being accredited soon, but we have been in business for 40 years, we havent setup a seperate company as a solar devision or anything like that so we wont be going anywhere, where as some of the solar only companies may soon be leaving the scene.

I would combine the above statement with looking to see how long they have been in business rather than when they did their first install.

I would be seriously concerned myself in handing over a few thousand to companies that havent been here that long, thats where i would be looking.

Thats my view and the view of many of the suppliers ive been talking to, as they have put a lot of their customers on payment on delivery rather than credit accounts.

 

[moggy1968]

there is no value to using a 4000TL over say a fronius 3.6 on this install unless you need dual mppt, in which case other 3.6 inverters are available. An inverter works most efficiently close to it's max so, according to PV sol, a 3.6 will actually yield slightly better than a 4000. I know this seems counter intuitive but thats the way it is, especially as your panel output starts to drop off over time. fitting a 4000TL will just delay your install because of needing prior consent from the DNO. Likewise your return may be better accepting a lesser panel (but not junk!) than the Sanyo rather than missing the deadline. A merc is still a nice car even though it's not a maybach!
I would agree with the above that most of the electrical firms doing Solar, either under a different company as we are or under their own company will be here for the long haul. They will tend to give better technical advice and less sales fluff.

 

[ExtremePV]

I would suggest the Fronius 3.6 TL. Its limited to 16A, so simple G83 install and as moogy said will outperform the SB4000TL. It only has a single mppt so one long string of panels. So as long as you don't need the twin trackers of the SB4000TL, I would go with the Fronius.
Check with the Fronius software to make sure it works with panels.

 

[GaryM]

I would suggest the Fronius 3.6 TL. Its limited to 16A, so simple G83 install and as moogy said will outperform the SB4000TL. It only has a single mppt so one long string of panels. So as long as you don't need the twin trackers of the SB4000TL, I would go with the Fronius.

Don't hold me to it but I think the voltage of 17 N235's on a single string will be too high for a Fronius 3.6 TL.

 

[ExtremePV]

Doh! ... well spotted GaryM... helps if I get the right panel... E4 model works, E10 doesnt.