Over9000
3rd Shift Ass. Manager @ 2nd-Hand Adult Toy Store
that only goes so far.
Solar Sizing | I thing I done goofed.
- Thread starter Over9000
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that only goes so far.
42OhmsPA
Who likes Electrical Gremlins?
It does, inverters make heat in operation too.
Over9000
3rd Shift Ass. Manager @ 2nd-Hand Adult Toy Store
That's true, but this year was cold as shit and hit -10 several times. We're talking a 40 degree swing to compensate for if I wanted to use one of the other choices.
42OhmsPA
Who likes Electrical Gremlins?
Insulation is an amazing thing.
Over9000
3rd Shift Ass. Manager @ 2nd-Hand Adult Toy Store
It ain't that amazing! But it's helpful.
42OhmsPA
Who likes Electrical Gremlins?
I camped in a hammock in single digit temperatures... It's amazing. Lol
Over9000
3rd Shift Ass. Manager @ 2nd-Hand Adult Toy Store
Your gas was keeping you warm, and I'm not talking propane.
42OhmsPA
Who likes Electrical Gremlins?
Similar to the inverter / AIO efficiency losses keeping themselves warm in a well insulated shed.
Over9000
3rd Shift Ass. Manager @ 2nd-Hand Adult Toy Store
One smelled though.
Over9000
3rd Shift Ass. Manager @ 2nd-Hand Adult Toy Store
Hey folks,
Each of my panels is 41.75VoC @ 14.13A. I have (9) of them and want to run (3) strings of (3) = 3s3p configuration.
I checked my new inverter (SGN7.6K1HB-48) and it doesn't have built-in PV breakers for its (3) MPPTs. However the unit does have a "PV Switch" on the side of it.
Do I need a PV String Combiner in this case? If so, is there a good one that I should use where I can have breakers instead of fuses?
Please let me know your thoughts. Thanks!
Each of my panels is 41.75VoC @ 14.13A. I have (9) of them and want to run (3) strings of (3) = 3s3p configuration.
I checked my new inverter (SGN7.6K1HB-48) and it doesn't have built-in PV breakers for its (3) MPPTs. However the unit does have a "PV Switch" on the side of it.
Do I need a PV String Combiner in this case? If so, is there a good one that I should use where I can have breakers instead of fuses?
- If I need one, this product (link) is seemingly a good option and then I'd just need (3) 20A breakers to go with it.
Please let me know your thoughts. Thanks!
Brucey
Velcro Man
For my 5s3p config on my 250/100 I use Staubli branch connectors for the paralleling and 15A mc4 inline fuses prior to each branch to protect each string.
Staubli 32.0196 MC4 Branch Connector MC4-Evo 2 Female
Shop now for Staubli 32.0196 Branch Socket MC4-Evo 2 Female PV-AZB4-EVO 2-UR.
www.stellavolta.com
Stäubli 32.0197 MC4 Branch Connector MC4-Evo 2 Male
Shop now for Stäubli 32.0197 MC4 Branch Connector MC4-Evo 2 Male PV-AZS4-EVO 2-UR.
www.stellavolta.com
Over9000
3rd Shift Ass. Manager @ 2nd-Hand Adult Toy Store
For my 5s3p config on my 250/100 I use Staubli branch connectors for the paralleling and 15A mc4 inline fuses prior to each branch to protect each string.
Staubli 32.0196 MC4 Branch Connector MC4-Evo 2 Female
Shop now for Staubli 32.0196 Branch Socket MC4-Evo 2 Female PV-AZB4-EVO 2-UR.
Stäubli 32.0197 MC4 Branch Connector MC4-Evo 2 Male
Shop now for Stäubli 32.0197 MC4 Branch Connector MC4-Evo 2 Male PV-AZS4-EVO 2-UR.
I'm a bit confused. I have (3+) and (3-) strings which I can run directly to my AIO unit which has a PV Switch on it.
Do I need to fuse / add breakers in between? If so, what's the best way to do it?
42OhmsPA
Who likes Electrical Gremlins?
Regardless what the spec sheet says, I don't think that inverter for perform optimally with the panels in a 3S config.
Yes, you need one.
You can't go wrong with Midnite.
You can also build one pretty easy.
I attached one I put together with breakers (disconnects) and fuses a few years ago. I've reconfigured it a couple times as I've expanded.
I also have a disconnect at each of my ground mounts, 7S2P for one and 10S for the other.
Attachments
Brucey
Velcro Man
I'm sorry I thought you were trying to connect three parallel strings of three to a single mppt . When you say things like 3s3p we think you are connecting that to a single mppt, and then you need fuses or breakers. Combiner box etc.
If you only have 9 panels yes just have three strings of three going to the three mppts. No combiner box needed. But that inverter needs 90V minimum to start its mppts. You could potentially have issues getting to that level with only three panels per string (use Vmp figure for that calculation), especially in the heat of summer.
Given you have a 540V top end limit then I would suggest 5 panels on one mppt and 4 on the second, leave third one free.
Over9000
3rd Shift Ass. Manager @ 2nd-Hand Adult Toy Store
Vmp is 34.5V, so 3x 34.5V = 103.5V. Do you think it would really have issues clearing 90V? 10V at that point is a pretty big swing.
My array is literally a 3x3 grid, so it's easy for me to do 3 strings of 3 and then just run each string into its own MPPT input.
If I can run directly into the MPPTs - and it has a "PV Switch" - do I need to put inline fuses for each string prior to inputting them to the MPPTs?
MisterSandals
Participation Medalist
From my understanding, until your SCC starts up, it will see 3x Voc for voltage. Once it starts, the voltage will be pulled down to Vmp. And then once started, the MPPT range is down at 70V-540v. Sounds a little unusual but as spec'd, it sounds like 103.5Vmp will work.
Solar Guppy
Red Cobra Guppy
3 panels in series won't work, vmp listed is when the PANEL is at 25C ( typically they can run +25-40C on top of ambient in hot weather )
Over9000
3rd Shift Ass. Manager @ 2nd-Hand Adult Toy Store
Can you explain this more? The math ain't mathing for me.
Brucey
Velcro Man
Just as you need to calculate maximum voltage in record cold weather for winter, in the summer heat the reverse is true, voltage will drop. Now that's usually not a concern however when running smaller strings you can run into the minimum startup voltage.
I guess no harm going with 3s strings and if it turns out thats not enough in the summer change them around to 5s and 4s.
You dont need additional fusing for your planned config of 3 in series to separate mppts.
Solar Guppy
Red Cobra Guppy
Have you calculated the range of voltages for your climate? Data sheet values are for cell temperatures, not ambient temperature and in my testing ( lab I did design work with ) where I had thermo-couple's on my arrays cells the +25-40C was typical in my climate over ambient.
I did this so I could calculate in real-time the expect mppt voltage and verify my code was working correctly as well as with competitors that didn't ....
I did this so I could calculate in real-time the expect mppt voltage and verify my code was working correctly as well as with competitors that didn't ....
Over9000
3rd Shift Ass. Manager @ 2nd-Hand Adult Toy Store
Okay. Previously I had all (9) panels in series and ran them through an inline fuse before going into a single MPPT. Was that the right thing to do?
MisterSandals
Participation Medalist
Yes but you don't need the inline fuse. A switch or breaker for PV shutoff is always a must.
Brucey
Velcro Man
There's no need for a fuse or breaker for a single string or two strings in parallel. They serve no purpose. Once you parallel three strings or more thats when you need ocp.
42OhmsPA
Who likes Electrical Gremlins?
I was incorrect in saying you needed a combiner above, your 3p threw me off...
Just run 9S to one MPPT and use the others when you add more panels.
I'd still run the string(s) to a fuse or disconnect between the MPPT(s).
I also think the 5S and 4S approach mentioned above would be much better then your proposed 3S.
Keep the voltage high, amps low and wires cool....
Just run 9S to one MPPT and use the others when you add more panels.
I'd still run the string(s) to a fuse or disconnect between the MPPT(s).
I also think the 5S and 4S approach mentioned above would be much better then your proposed 3S.
Keep the voltage high, amps low and wires cool....
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