Too many panels in parallel?

[400bird]

The layout is definitely not optimal. It's due to the shape of my roof. Many angles, curves, etc. When I post images on my other thread you'll be able to see. Definitely not the best roof for solar. Also I checked the 18kpv manual and took the screenshots to post for this thread. It mentions 100-600v per MPPT. My interpretation is that the totality of MPPT 1 can be 600v. So 405v on each channel of the MPPT 1 would then be 810v total on MPPT 1.

Nope, each MPPT 1 input channel is in parallel. Add current, not voltage

For the proposed 5s strings, it's within the operating range but not the "Full Power" range on the MPPT. I'm not sure what this means. You might want to call your vendor on that one. Or someone here may be able to help fill in that detail.

 

[timselectric]

It mentions 100-600v per MPPT. My interpretation is that the totality of MPPT 1 can be 600v. So 405v on each channel of the MPPT 1 would then be 810v total on MPPT 1.

Chanel 1 and 2 on MPPT 1, are internally connected in parallel. So it would be 405v.

 

[LydMekk]

If noone has mentioned it (can't cba to scroll back)...there is a difference between the inverter max PV voltage and the internal MPPT chargers max voltage. The latter is usually way less, f.ex. 425V or 450V. Read your manual! Also, ind cold weather the volts go up.
For example on an inverter with 425V max MPPT I would not go over 400V aka 8 modern panels in series per string.

 

[thetubernoober]

If noone has mentioned it (can't cba to scroll back)...there is a difference between the inverter max PV voltage and the internal MPPT chargers max voltage. The latter is usually way less, f.ex. 425V or 450V. Read your manual! Also, ind cold weather the volts go up.
For example on an inverter with 425V max MPPT I would not go over 400V aka 8 modern panels in series per string.

I've been going through the manual a bit but i'm not very experienced in electrical. My main reason is i'd like to learn what's going on whilst monitoring the installers to ensure of no hiccups. It's the same reason I don't try to attempt any DIY. Though I know less than them, it's why I usually check through the manual and bring something that comes to my attention to this forum. Thanks for the info on the differences between inverter max pv and internal MPPT chargers max. Learning something new everyday. As for cold, I never need to worry about that, it never gets below 70F lol.

 

[740GLE]

Another thing to bare in mind is that it's ok for the PV calculations to exceed the amperage of the MPPT input (25A), because the inverter will limit the current anyway. The big advantage is that you'll have more power during lower solar (cloudy, etc) energy days. This is great so long as you have the budget and physical space to 'overclock' your PV arrays. Just remember that the PV array(s) connected to MPPT1 must match exactly as they are paralleled inside the inverter.

I would argue with that.

It may just be my preference to not push the limit, but my understanding is that Isc limit of the MPPT is to handle shutting off current in an emergency situation.

 

[HRTKD]

Since the amperage on MPPT 1 is 25 amps, while MPPT 2 and 3 are less, that agrees with channels 1/2 on MPPT 1 being in parallel. With each channel's string being east/west you should be fine. I don't see you exceeding 25 amps with that alignment.

 

[thetubernoober]

Since the amperage on MPPT 1 is 25 amps, while MPPT 2 and 3 are less, that agrees with channels 1/2 on MPPT 1 being in parallel. With each channel's string being east/west you should be fine. I don't see you exceeding 25 amps with that alignment.

I believe I should be good on amperage as well. My main concern now is that of the Full Power range of the inverter. I don't know how 3 separate installers can miss such a crucial part of array design. Guess it's time to find a 4th installer. At this rate the install will cost more than the system lol.

 

[Sigunas]

I believe I should be good on amperage as well. My main concern now is that of the Full Power range of the inverter. I don't know how 3 separate installers can miss such a crucial part of array design. Guess it's time to find a 4th installer. At this rate the install will cost more than the system lol.

Are you sure you understand correctly what the installers are telling you? It seems like a lot of guidance for electricians from someone who doesn't distinguish between series and parallel connections.

 

[thetubernoober]

Are you sure you understand correctly what the installers are telling you? It seems like a lot of guidance for electricians from someone who doesn't distinguish between series and parallel connections.

From the moment the first installer ran all panels positive to positive and negative to negative and was telling me it was series I kinda figured things were a bit off so I decided to check myself. I do not understand everything at all but I keep track of what they are doing, then try to research it a bit, and get input from the forum. I always ask what step of the process they are in and for an explanation of what they are doing. I then go and check it myself. Solar is very new where I am so it's hard to find installers with tons of experience. I always get a second opinion regardless of how much of an "expert" is working on my system. At the end of the day, I spent close to $40,000 on my system and if it gets ruined by an installer I don't think they'll foot the bill for replacement.

 

[x98myers7]

so... i'm going to ask a bunch of questions that all play in to what you're asking. FilterGuy did the math... but IMO we don't have enough info yet....

are you in the USA? what climate are you in? do you need to account for temperature correction due to freezing? that won't push the VoC enough but you're already at 21.92amps.

is anything being installed through an attic space? if so, are they accounting for high-temp derating in your wiring?

btw... since this is a residential install, are your EG4 units UL listed? will the system be inspected? how are you accounting for AFCI and RSD since EG4s support neither?

 

[zanydroid]

btw... since this is a residential install, are your EG4 units UL listed? will the system be inspected? how are you accounting for AFCI and RSD since EG4s support neither?

18KPV definitely has everything you need for rooftop install. Including UL9540

6000XP I'm not sure about, but I think it does have AFCI, and RSD is no big deal to add.

Older ones, probably not. Maybe the 8K but that ones a shitshow for other reasons.

 

[x98myers7]

18KPV definitely has everything you need for rooftop install. Including UL9540

6000XP I'm not sure about, but I think it does have AFCI, and RSD is no big deal to add.

Older ones, probably not. Maybe the 8K but that ones a shitshow for other reasons.

okay, yeah... I stand corrected on the 18kpv...

carry on.

 

[Sigunas]

installer ran all panels positive to positive and negative to negative and was telling me it was series

OK, sorry, I take back my words about guiding electricians.
You have 30 panels that you plan to arrange in three directions, an inverter with three MPPT inputs. Great.
x98myers7 asked very good questions. Until they are answered, general guidance would be:
you need to arrange the panels in such a way that they get as little shade as possible, and each of the 3 strings consists of at least 6 and no more 12 (or even 11 if very low temperatures are possible) serially connected panels, directed in the same direction. You even have the option to connect 4 strings and 2 of them connect parralel to MPPT1

 

[thetubernoober]

so... i'm going to ask a bunch of questions that all play in to what you're asking. FilterGuy did the math... but IMO we don't have enough info yet....

are you in the USA? what climate are you in? do you need to account for temperature correction due to freezing? that won't push the VoC enough but you're already at 21.92amps.

is anything being installed through an attic space? if so, are they accounting for high-temp derating in your wiring?

btw... since this is a residential install, are your EG4 units UL listed? will the system be inspected? how are you accounting for AFCI and RSD since EG4s support neither?

I'm not in the USA but our country uses the same style of electrical grid. Split phase 120/240 60hz. I live on a Caribbean island, the coldest it has ever gotten in history was 52F. Average year round is 70F-91F. Nothing will be in the attic space as wiring runs from roof to outside corner edge then directly into the wall where the battery storage is.

 

[x98myers7]

I'm not in the USA

ah... gotcha. that explains the lack of knowledge on your installers. most electricians in the USA still won't touch solar unless is a microinverter/AC based system.

just make sure the wiring is 90degC rated. 10ga should be sufficient then.

 

[thetubernoober]

OK, sorry, I take back my words about guiding electricians.
You have 30 panels that you plan to arrange in three directions, an inverter with three MPPT inputs. Great.
x98myers7 asked very good questions. Until they are answered, general guidance would be:
you need to arrange the panels in such a way that they get as little shade as possible, and each of the 3 strings consists of at least 6 and no more 12 (or even 11 if very low temperatures are possible) serially connected panels, directed in the same direction. You even have the option to connect 4 strings and 2 of them connect parralel to MPPT1

Not a problem, no offense was ever taken. First installer was apparently a linesman and an electrician was to look over the work and i guess didn't bother looking at how the panels were connected. Second installer was using a voltmeter checking amperage for loads and was wondering why he was getting constant 60 "amps". Took 4 readings and in the end his coworker told him the meter was on hertz. So got rid of those quickly. Currently on the 3rd installer .

I'm going to tell the current installer to stick to the 8x8 on MPPT 1 and 7 MPPT 2 and 7 MPPT 3.

 

[thetubernoober]

ah... gotcha. that explains the lack of knowledge on your installers. most electricians in the USA still won't touch solar unless is a microinverter/AC based system.

just make sure the wiring is 90degC rated. 10ga should be sufficient then.

There's surely some incompetence due to lack of experience but I don't hold it to them personally. At the current rate my plan is to either hire an electrician from the US to virtually(via phone) go through all of the wiring prior to initiating the system. If that's not feasible then I'll be paying one to fly here. Worth the investment not to have a 40k system blow up in smoke.

 

[timselectric]

At the current rate my plan is to either hire an electrician from the US to virtually(via phone) go through all of the wiring prior to initiating the system.

We are here and free.
Take advantage of this forum.

 

[740GLE]

Timselectric consulting and advice

 

[timselectric]

Timselectric consulting and advice

I said "we" , as in the huge knowledge base of the entire forum.