# of panels for charge controller

[jmygann]

Have 18 sharp 240w panels ...  could use 16 or 18 of them ..  3 in a string or  ..  4 in a string

Maximum Power (Pmax)* 240 W

Tolerance of Pmax +10%/-5%

Type of Cell Monocrystalline silicon

Cell Confi guration 60 in series

Open Circuit Voltage (Voc) 37.4 V

Maximum Power Voltage (Vpm) 30.1 V

Short Circuit Current (Isc) 8.65 A

Maximum Power Current (Ipm) 7.98 A

Module Effi ciency (%) 14.7%

Maximum System (DC) Voltage 600 V

Series Fuse Rating 15 A

NOCT 47.5°C


Grid with battery back up  48 volt

How to string them ??  .

which single charge controller ?  150 or 200 (now the same price)

temperatures ....20 deg to 110

.

[Westbranch]

try using this tool, the online wizard

http://www.midnitesolar.com/classic/classicCP.php

[Halfcrazy]

I have a new string sizing tool as well. I will get it on the website Friday and link to it here.

Ryan

[Kent0]

Sounds like you are trying to maximize the array size, so unless the array is a far away from the charge controller, you'll be best off with a Classic 150.

It looks like six strings of three will be a comfortable match to the 150. You might get away with seven strings of three.  The question is: how does the Classic hold up if you push it to the limit?

I hope the new online sizing tool has an answer for that.

[jmygann]

I was thinking 6 strings of three for 18 panels ....    or

4 strings of 4  using 16 panels.........looks like a classic 200 is needed

[Kent0]

Three strings of five does require a Classic 250. I would look at the array distance and wire size needed before deciding which arrangement works best. Since you are considering a pole-top mount, you also have to consider how many modules fit on the pole mount. It's possible to put fifteen on one pole. It's a big structure! Even 12 on a pole is big.


Edit -
A Classic 200 would work with three strings of 5. But when the temperature is below 41°F it is in hyper VOC mode.

[jmygann]

This type of pole mount ...  http://aetenergy.com/assets/pdf/t6-cutsheet-HR.pdf

ended up getting 18 sharp 240w panels

Maximum Power (Pmax)* 240 W

Tolerance of Pmax +10%/-5%

Type of Cell Monocrystalline silicon

Cell Confi guration 60 in series

Open Circuit Voltage (Voc) 37.4 V

Maximum Power Voltage (Vpm) 30.1 V

Short Circuit Current (Isc) 8.65 A

Maximum Power Current (Ipm) 7.98 A

Module Effi ciency (%) 14.7%

Maximum System (DC) Voltage 600 V

Series Fuse Rating 15 A

NOCT 47.5°C

.

[Kent0]

Do you plan on a fence around the PV array? NEC 690.31(A) requires that all accessible wiring above 30 volts to be in conduit. Since the modules don't have junctions boxes for connecting conduit, the wiring should be inaccessible. Technically, even with a microinverter installation, as shown on the mount literature, a barrier to prevent access is required because the open circuit voltage of the modules exceeds 30 volts. For your system, with strings of three modules, it'll be way over 30 volts.

[jmygann]

did not know about the fence  ...  had not planed to do this.

Maybe better to put on roof.

either way  and given the same price , is the 250 a better way to go ??

[Kent0]

It doesn't have to be a fence; any barrier to prevent access should be allowed. It would be best to check with the local authority having jurisdiction. Roofs are considered inaccessible. There are many reasons to consider or exclude the roof. Depends on the situation and owner preference.

To decide on which Classic is the best, the array size and the distance to the array both need to be considered. The only advantage to the higher voltage string is lower current which allows smaller wire to be used. You have to evaluate the total cost of the installation both ways.

[jmygann]

with these panels  ..  it will be 3 in a string  x 6 strings = 18 panels

either the 150 or the 200 will work  ... they are the same price ..  just wondering if there is any reason  not to get the 200 ??

[Kent0]

With 18 modules the Classic 200 is a not the best choice. Nominally the array puts out 4300 watts at 90 volts and, at 58.4 volts, the battery charging current will be near 74 amps. If the Classic is in a 25°C location, it is rated for 70 amps for a 70-volt array and 78-amps for a 120-volt array. At 90-volts maybe it'll work fine with 74 amps out. But in a 40°C location, the 200 is only rated for 66 amps. So it would be pushing the 200 near or past its maximum power limit.

Consider the Classic 150. It's rated for 80 amps even in a location where the temperature is 40°C. Even if you were in a location where the PV modules got a really cold -40°C, the voltage of the array wouldn't be an issue either.

[jmygann]

when is the 200 more desirable than the 150 ?   if I went with 16 panels ...  4 per string and 4 strings then the 200 works better with fewer panels ??

Open Circuit Voltage (Voc) 37.4 V x 4 = 149.6

[Kent0]

Correct, stepping up to the Classic 200 with strings of four modules is appropriate when the array needs to be some distance away. That configuration won't work with the Classic 150, except perhaps in tropical climates. For most places, the four in series arrangement requires the Classic 250. The penalty is that it doesn't handle as much power as the Classic 150. With the Sharp 240-watt modules four strings of four in series (an impressive 3840 watts) is pushing it to the maximum that it will handle in a 40°C environment. Operating at 32 amps and 120 volts, the voltage drop at 125 ft with 4 AWG would be 2%. And with 2 AWG it is 2% at 200 ft.

If you really want the PV array a long ways off, the Classic 250 will handle 2 stings of six modules. That's 2880 watts; still an impressive amount of power but quite a bit less than the Classic 200 handles. With 2 AWG, the voltage drop is 2% at 600 feet.

[jmygann]

. The penalty is that it doesn't handle as much power as the Classic 150. .

the 150 handles more power ??