OP
JulianC
Each panel is wired to an optimizer, then the optimizers are connected in series strings as per usual
Discuss I am a new PV householder - advice please. Unbalanced strings and wrong inverter in the Solar PV Forum | Solar Panels Forum area at ElectriciansForums.net
Each panel is wired to an optimizer, then the optimizers are connected in series strings as per usual
As Gavin says: in summer it won't matter.
But with low sun in winter (or early/late in the day at other times of year), the difference in angle will make a big difference to panel output, so the bypass diodes will be working overtime.
By my reckoning, a 5-degree difference (35 v 30 degrees) in angle affects as follows:
Mid-day, June sun: 0.5%
Mid-day, March/Sept sun: 5%
(comparable to morning/afternoon summer sun)
Mid-day, December sun: 20%
(comparable to early-morning/late afternoon spring/autumn sun)
Busy week... The installer has come back saying they will install the quoted GroWatt inverter, use fire retardant board etc.
I am going to struggle to get out of a signed contract where they have offered to comply with the contract.
Whats the worst that could happen with
Growatt 3600MTL (2 MPPTs)
12 x 245w panels on a 30% roof
4 x 245w panels on a 35% roof
Could be wired 8+8 according to Growatt tech support, though that was before I knew about roof angle, and they haven't answered my recent question.
In another thread, FB said
Will that amount to much over the year?
Is bypass diodes working overtime a big problem?
Thanks...
When did you sign the contract as you have 7 days cooling off period
Well they are supposed to be coming up with a quote for Solar Edge with 16 Optimisers by tomorrow. I will have to see what the difference is.Maybe you could say to them you are not happy with the equipment being installed
you want an power one inverter as you can alter the start up voltage on the mppt
Well they are supposed to be coming up with a quote for Solar Edge with 16 Optimisers by tomorrow. I will have to see what the difference is.
Accepting that Solaredge is probably the best solution, but if your installers did not offer it (or knew anything about it?) originally - do you want to be their first 'guinea pig' solaredge installation in these particular circumstances?
A good point of course, but I am running out of time and options. But how hard can it be plugging 16 optimisers into the back of 16 panels and plugging them in one string into an inverter? OK, I was joking - that's why you are the experts and I am just the unfortunate punter! Is there any technical configuration to do in the inverter, or does it set itself up? I must say that having the Solar Edge transmitting data to the web is sounds interesting...
By the way, this was the Growatt Tech Support answer to my question "Our 2 roofs face in the same direction but they do NOT have the same angle - the 12 panels would be at 30% to the horizontal, and the 4 panels would be at 35% to the horizontal. Can we still use the 3600MTL wired 8+8?""5% should not be that much that affect the overall performance. In some instances 4 panels may be able to produce more that the 4 others, but limit their power production to the low ones. I am assuming this will be a 8+8 config using a 3600MTL".
So if the extra for Solar Edge is too much, we just settle for the Growatt with 2 MPPTs wired 8 + 8, since that is the contract we have signed up to.
I just need to decide how much is too much... Answers on a postcard.
I've just checked, and both inverters have the same MPPT lower voltage of 120VMaybe you could say to them you are not happy with the equipment being installed
you want an power one inverter as you can alter the start up voltage on the mppt
Thanks, though when you say this inverter, which did you mean??I've just checked, and both inverters have the same MPPT lower voltage of 120V
120V simply isn't low enough for 4 x 30.5V panels, because as soon as the panels warm up even a little the voltage will go outside the MPPT voltage range and shut down that MPPT.
Combining the 4 panels on that roof with 1-4 from the other roof is the only viable option with this inverter (or power one / sma equivalents).
tbh there's not going to be a lot of difference between a 30 and 35 degree roof, and the dual MPPT will minimise this impact. It's not ideal, but then any losses from doing this are likely to be lower than the reduction in efficiency from swapping to a seperate smaller inverter for that roof, so I understand this companies reasoning.
They probably should have explained this better themselves though.
Even if split 12 panels at 30% to the horizontal, and 4 panels at 35% to the horizontal?You could probably get away with a 6 and a 10 string on a dual tracker to minimise losses, but still close to the lower end of the tracker voltage range.
Another possible alternative. Maybe someone knows.
Would 72 cell panels like the znshine have enough voltage for a string of 4 panels?
Even better get an installer who knows what they are doing. I dont understand how people can take such risks to save a few quid ????
Oh how hindsight is a wonderful thing.
Even better get an installer who knows what they are doing. I dont understand how people can take such risks to save a few quid ????
Well it was last Friday, but I stopped them half way through when I discovered the problem. I am waiting for them to come back with a proposal inorporating Solar Edge + optimisers today, then when I have made a decision (the alternative being to revert to the quoted Growatt inverter wired 8+8 or 6+10) I will ask for next Friday since I will be home then. Friday 13th. Gulp.When is your installation date
What modules have they given you, sorry I havnt been following what the issues were.
Sorry, I have only just seen this.How much is the pitch difference? I'm actually attending a Solar Edge technical conference today and would certainly say they are what you need in this case. Also I really doubt they would add 10% to the overall system cost.
Sent from my HTC Desire S using Tapatalk 2
Yes, this was their rationale - similar inverter prices plus the 16 optimisers.Actually this is about right. The solaredge inverter is similar in price to, say, an Aurora one. In this configuration you need 16 power optimisers which would make up most of the 10%, then you need to allow for the addtional back room work (solaredge registration etc). Still think the extra would be worth paying, but OP seems not to be convinced.
yes looks like the four panels might as well not be there as they not going to start up the MPPT! as stated above .
Tricky one they should of either used a Mastervolt 600 for the four panels then a single tracker inverter for the other 12.
or gone for solar edge the dip sticks !!!
Makes me laugh really does
Glad I caused some amusement! (I don't mean that is an offended way).But we like a laugh.
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