Combiner Box Question

[Krazy1]

Hi all, I am about to install solar for my shop at my house. Here are the specs on what I'm installing:

6 each Topoit 245 watt Mono panels
Watts (STC) 245W
Watts (PTC), No
Maximum Power (Vmp) 49.51V
Maximum Current (Imp) 4.95A
Open Circuit Voltage (Voc) 59.45V
Short Circuit Current (Isc) 5.54A
Power Tolerance ±5%
Module Efficientcy No

My equipment is:
Outback GVFX3648 Inverter/Charger, 3600W, 48VDC, 120VAC, 45A charger
Outback FLEXmax FM80 Charger Controller
Outback MATE3 Control Module and Display
Outback HUB-10 Communications Manager
Outback RTS Remote Temperature Sensor
Prewired AC and DC boxes with 120VAC Bypass and Type B Outlet
FLEXnet DC
surge protector for 120V 60Hz applications
80 amp charge controller breaker
175ADC breaker
GFDI
1 x PSX-240 Auto transformer

Now my question is, how can I tie them all together in parallel? How many string before I need a combiner box? Can I use branch connectors and bring one run down to a fused DC disconnect? My intentions are to add more panels at a later date and time. Thanks in advance for any help.

[Mike90250]

Your panels are 45V, batteries 48V, so there must some panels in series.

I would wire 2 panels in series, then parallel the three series strings with 3 combiners. Do the panels have a series fuse spec on the label ? Otherwise I'd use 10A fuses or DC breakers.

[Krazy1]

Your panels are 45V, batteries 48V, so there must some panels in series.

I would wire 2 panels in series, then parallel the three series strings with 3 combiners. Do the panels have a series fuse spec on the label ? Otherwise I'd use 10A fuses or DC breakers.

Thanks for the input Mike. I was not quite sure if my panels would charge my 48volt bank without configuring one in series. Is there a rule of thumb for us beginners when sizing the panels for charging 12, 24, and 48 banks? I was aware that I would need to output much more than the 48v.

[Krazy1]

Here is the complete spec on the panels:

Electrical Characteristics
Watts (STC) 245W
Watts (PTC), No
Maximum Power (Vmp) 49.51V
Maximum Current (Imp) 4.95A
Open Circuit Voltage (Voc) 59.45V
Short Circuit Current (Isc) 5.54A
Power Tolerance ±5%
Module Efficiency No
Mechanical Characteristics
Cell Technology Monocrystalline
Cell Size Others
Cells Per Module 96
Dimension 1575*1082*50mm
Weight 21.5000
Frame Material Anodized Aluminum
Module Color Silver Frame
Moduel Connector MC4 or Compatible
Junction Box IP65
Output Cable No
Operating Conditions
Maximum System Voltage 1000VDC
Operating Temperature -40℃--85℃
Maximum Series Fuse 10A
Max Snow Load 5400Pa ( 112 lb/ft2)

[Mike90250]

Here is the complete spec on the panels:...
Maximum Series Fuse 10A......

10A fuse or circuit breaker. in each of the parallel strings

[Amy@altE]

You have 96 cell modules, which are "nominal 32V". A 12V panel is 36 cells. Each cell (the individual block of silicon) is about .33V nominal. So .33V x 96 cells = 32V nominal. You have a nominal 48V battery bank. Nominal voltage is a term used to be able to see at a glance what equipment works together, a nominal 12V solar panel works with a nominal 12V battery bank, even though neither are actually 12V. So since you have a nominal 32V panel, you need to wire 2 in series to get a higher nominal voltage than your battery bank, that charge controller can adjust down, but not up. You can only do 2 in series, because the charge controller can only handle up to 150Voc, including temperature deration (voltage goes up when it's cold). 59.45 x 2 in series x 1.2 for cold (guessing where you are) = 142V.

Then get a Midnite MNPV6 (for room for expanding) combiner box with 3 10A fuses and 4 2-hole strain reliefs for the wire to enter (including one for grounding wire). That will combine the panels into 3 parallel strings of 2.

Amy

[Krazy1]

Wow, I'm so glad I posted on here. Thanks for all this good information. This forum is fa nominal!!

[Krazy1]

You have 96 cell modules, which are "nominal 32V". A 12V panel is 36 cells. Each cell (the individual block of silicon) is about .33V nominal. So .33V x 96 cells = 32V nominal. You have a nominal 48V battery bank. Nominal voltage is a term used to be able to see at a glance what equipment works together, a nominal 12V solar panel works with a nominal 12V battery bank, even though neither are actually 12V. So since you have a nominal 32V panel, you need to wire 2 in series to get a higher nominal voltage than your battery bank, that charge controller can adjust down, but not up. You can only do 2 in series, because the charge controller can only handle up to 150Voc, including temperature deration (voltage goes up when it's cold). 59.45 x 2 in series x 1.2 for cold (guessing where you are) = 142V.

Then get a Midnite MNPV6 (for room for expanding) combiner box with 3 10A fuses and 4 2-hole strain reliefs for the wire to enter (including one for grounding wire). That will combine the panels into 3 parallel strings of 2.

Amy

FYI, I'm in northwest Florida. Lots of sun, not much wind unless a hurricane is coming!

[SunEagle]

FYI, I'm in northwest Florida. Lots of sun, not much wind unless a hurricane is coming!

Out of curiosity what is the voltage and AH rating of the batteries are you using for 48volt system?

[Amy@altE]

slight correction

I said 10A fuses, I meant 10A breakers.

Even in FL, you can't do 3 in series. 59.45Voc x 3 = 178V = boom

[Krazy1]

Out of curiosity what is the voltage and AH rating of the batteries are you using for 48volt system?

This is what I plan to use:

6 each,12 Volt 200 Ah Group 4D Deep Cycle Sealed AGM SCADA Systems Solar Backup Battery.But I'm open to any suggestions!

[Krazy1]

I said 10A fuses, I meant 10A breakers.

Even in FL, you can't do 3 in series. 59.45Voc x 3 = 178V = boom

Yes, I ordered my combiner box today with 10A breakers, not fuses. My plans were to test the system with all 6 panels in parallel first. Then if I need to, I had intentions of placing only 2 of the panels in series! Once my system and components arrive, I have an electrical engineer helping me wire it up. I'm still up in the air whether or not to place combiner on the roof or add the extra wires to put it inside near all the controls.

[SunEagle]

This is what I plan to use:

6 each,12 Volt 200 Ah Group 4D Deep Cycle Sealed AGM SCADA Systems Solar Backup Battery.But I'm open to any suggestions!

I am not sure how you can configure 6 x 12volt batteries into a 48volt system.

First off unless you are worried about fumes or spillage a Flooded Lead Acid (FLA) deep cycle battery is better then AGM type batteries.

Second you should build the system with batteries wired in series and not in parallel.

What is your daily watt hour need? If for example it is around 4000 watt hours then I would say 8 x 6 volt 420Ah Trojan L16P would give you a 48V system good for about 4kWh using about 20% of the battery capacity.

If your daily load is more than 4kWh then even in Florida your 1470 watt panel system may not be enough to put back what you used during the Winter.

A solar battery system requires all of the components to be balanced.

If you haven't read them yet go to the Off Grid Section of this forum and read the Sticky posts on sizing an off grid battery system. Below is the link to that post. There are others in the same area that will help you understand what you need and what to get.

http://www.solarpaneltalk.com/showthread.php?5334-Solar-Off-Grid-Battery-Design

[russ]

I am not sure how you can configure 6 x 12volt batteries into a 48volt system.

It is that new math I guess - you can get most any answer you want and it is OK - you still get a ribbon.

[SunEagle]

It is that new math I guess - you can get most any answer you want and it is OK - you still get a ribbon.

Either that or he typed in the wrong quantity.

I think he meant to say 8 x 12volt 200Ah batteries. Which would require some parallel wiring. So I suggested 8 x 6v 420Ah batteries wired in series. Cleaner installation as far as I'm concerned.

He needs to have a good battery system to meet his needs, especially since he purchased that Outback Hybrid inverter/charging system for around $4000.