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
.
try using this tool, the online wizard
http://www.midnitesolar.com/classic/classicCP.php
I have a new string sizing tool as well. I will get it on the website Friday and link to it here.
Ryan
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.
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
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.
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
.
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.
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 ??
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.
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 ??
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.
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
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.
Quote from: Kent0 on March 16, 2012, 11:17:23 AM
. The penalty is that it doesn't handle as much power as the Classic 150. .
the 150 handles more power ??
Yes, the Classic 150 is rated for lower input voltage but it handles more power. Take a look at the Classic power curves (http://www.midnitesolar.com/images/classicFrontPage/graphs.php). Notice that for a 48-volt battery with a 120-volt PV array the current rating of the Classic 150 is 76 amps (or 4434 watts) and the rating of the Classic 200 is 70 amps (or 4080 watts).
But aren't these both the same in real terms? 58.3 v Or are there more losses in the 200? I was also looking for the reason not to get the 200 over the 150 but couldn't come up with one but if tHis is right there is 6amp loss at 120v in.
Well it is not loss it is simply a factor of the differential between the input and the output voltage causing things to run warmer. This is a case with any MPPT controller. So as the spread in voltage widens we have to back the max power down a little to keep things cool. So you are not losing that 6 amps you just cant push that many amps through the controller.
Ryan
Ok thanks, so is it best as said before that if you can use the 150 use it? I was of the thinking that the 200 is the one to get as it can handle more, I'm only having a 4kw system which are 20 200w voc 45.1 imp 5.5 vamp 36.4 isc 5.9 and they are only 1.4m to the closest panel run and 9.4 m to the furthest, combiner to cc is 0.5m and cc to battery is 0.375m...
What would you guys do?
Thanks
Marc
Quote from: Jonah on April 25, 2012, 10:43:21 AM
Ok thanks, so is it best as said before that if you can use the 150 use it? I was of the thinking that the 200 is the one to get as it can handle more, I'm only having a 4kw system which are 20 200w voc 45.1 imp 5.5 vamp 36.4 isc 5.9 and they are only 1.4m to the closest panel run and 9.4 m to the furthest, combiner to cc is 0.5m and cc to battery is 0.375m...
What would you guys do?
Thanks
Marc
Jonah,
At that short distance, I would wire the array for lower voltage presented to the controller and use the 150.
But not REAL low... If possible, run the input voltage higher than your nominal battery voltage by one or
2 12V multiples. For example, 48V battery, wire for around 60V array or 72V array. Higher voltages
are normally better for real long PV wire runs. You got short runs so that's good.
boB
Many thanks boB, so if I run 10 strings of 2 that'll have a voc of 90.2, vmp of 72.8 and 55 amps? Is that the best?
Thanks for your help.
Marc
Marc,
I would NOT run these 60-cell modules in strings of 2 in serise. For a 48 volt bank the Vmp of 60.2 volts will be insufficient in hot weather, doing an EQ (for FLA batts), or, at times perhaps even running an Asorb on a cold battery bank, if you are using FLA batteries.
Strings of three are dandy. This gives 90.3 Vmp string voltage, and the Voc should be fine unless you are at the Notrh Pole. The newest system here also uses 60-cell PV modules, and run strings of three also, for the reasons noted above.
Good Luck, Vic
Thanks Vic, unfortunately, I wired it all up before seeing your post... But... Mine are 72 cell 72.8v vmp panels so hopefully this will give it the extra they need.
Thanks
Marc
Hi Marc,
OK on the number of cells in the PV modules that you actually have. Was just going by the two references you posted previously .., "Cell Confi guration 60 in series" and 30.1 Vmp (which also indicates 60 cells.
In your post #20, you did indicate 72.8 would indicate 72 cells per module. If you ARE running two 72 cell PV modules in series, then you will be fine on a 48 volt bank. 72 cell PVs are real 24 volt modules. Sorry that I missed this change. Did note your ref to 90.2 Voc reference, but thought that was a misquoted Vmp on the 60 cell jobs.
You should be fine with the specs you noted, Good Luck swith the new system. Vic