What equipment needed for solar panels on FX 24v inverter

Re: What equipment needed for solar panels on FX 24v inverter

Yep... And a couple of points:

1. Check polarity of panel/controller connections. Should not cause damage--but you always want to be sure).
2. You don't really need a circuit breaker for a single connection... However, when you put three or more strings of panels in parallel, each panel string should have its own series protection breaker/fuse (roughly 2x Isc if not listed elsewhere). This limits the current if one panel gets an internal short so the other panels cannot over heat the shorted panel/wiring.

The panel voltage should be pretty stable at Voc with weak sunlight and a voltmeter as load (Voc peaks with minimal sunlight, and as the panels heat up, you may see a 10%-20%+ drop in Voc/Vmp voltage--that is normal). The panel output current is directly proportional to the amount of sunlight hitting the panel.

The 55 volts vs 65 volts is a pretty wide range of Vmp/Voc voltage... It will not hurt anything to connect them all in parallel--but it may not give you optimum power output from the charge controller.

When you get everything connected (all 16 panels--say 4 panels per string)... See what your total power output is in full sun with a discharged/loaded battery (so controller is in MPPT mode--maximum output current--Charged batteries will not accept full current).

If you are over ~60%% of your panels ratings (full noontime sun, clear day, etc.)--then you are probably doing the best you can... If you have less than 50% of panel rating, you might have to look at the array to find bad panels and/or try another configuration (try 4 strings of Brand A, measure power; then try 4 strings of Brand P, measure power--see how much total power from two tests vs everything connected together).

-Bill

Re: What equipment needed for solar panels on FX 24v inverter

Each series string of 4 panels (assuming that is your configuration) should then be connected + to + and - to negative (parallel, current will add, voltage will remain the same).

And, eventually, you should get some fuses or circuit breakers (your choice) to protect each series string (before you make the + parallel connection). Maybe around a 15 amp fuse/breaker for each series string.

This will reduce the chance of fire if a solar panel or solar panel wiring gets shorted.

You do not want the generator running while doing your Solar Charge Controller testing... You may see very little charging current from the solar charge controller because the AC battery charger is also supplying current to the battery bank (depending on battery voltage and each charge controller's voltage set-points).

-Bill

Re: What equipment needed for solar panels on FX 24v inverter

Yes, that would work and be "safe"... Two or one arrays do not need series protection fuses.

-Bill

Re: What equipment needed for solar panels on FX 24v inverter

Castilloj,

I am not the Outback (or any) programming expert here--so others may be able to help you better...

This Google Search "charge site:www.surrette.com" will give you the Rolls/Surrette recommended charging information.

Another good read is the Trojan User Guide (PDF Download). They have their recommendations in there...

If you are using the battery banks a lot--the Absorb Timer should probably set for a longer time and your system. And in the winter, you may never get into Float.

Also watch your battery water usage... If you use a lot--too much charging and crank down on the voltages/time. If you are using hardly any water--You may need to crank up the voltage and check if you are drawing too much power for the charging current you have available.

-Bill

Re: What equipment needed for solar panels on FX 24v inverter

castilloj wrote: »

Hey Bill, do these readings look ok from my MPPT60?

My impressions (again, I do not know Outback product except for what I read here):

Array voltage-45.91 V
--A bit too low... I would expect it to be more in the 55+ volt range in good sun and properly operating MPPT.

Input power-238.95 A
Battery Current-8.76 A
Output Power-239.61 W
Array Current-5.22 A
--Your arrays should each be around 6-7 amps maximum Imp in full sun/ideal conditions... You are getting less than 1/2 of that... I would try each array by itself and see what the Vpanel/Ipanel numbers are for each. You may have a dead panel or string.

Battery Temperature-37 C
--Very warm for a lead acid battery bank... Do you have a Remote Battery Temperature Sensor hooked up and configured? Or is this the Room/Charge controller temperature? (98.6F)? If the batteries are this warm--you should look at ventilation and other heat sources (sun through wall/window), etc.

LED State-Green
Target Regulation Voltage-30.07 V
--I do not know the Outback Terms... 30 Volts is a bit high for normal Bulk/Absorb charging. I would tend towards 29.0 volts or so. For Equalization of a battery bank, that is fine. (Note below, you are not hitting that voltage yet, see below, so nothing "bad" is happening yet). Just watch your electrolyte levels (both water levels, and specific gravity to tell you what your battery thinks of your loads/charging).

Battery Voltage 27.36 V
--Ideally, you should hit your "Target" voltage at least a once or twice a week (and stay there for a couple hours) to insure the battery is getting >90% state of charge.

Array VMP-(last sweep) 45.93 V
Array Voc(last Sweep)-58.73 V

--That Voc sounds a bit low... You should be hitting ~65-84 volts (depending on temperature and other loading issues)... I don't know "Outback", so I cannot tell you if this Voc is normal or not. In earlier posts you seem to have reported low Voc (Voltage open circuit)--Not usually a good sign for panel health. You may have one or two panels that are not performing well... If you can, with the system operating, measure the voltage across each panel--Ideally, each panel should match all the others within a volt or so. More than that, you have a bad panel/poor connection somewhere.

Array Pmax(last sweep)-242.69 W
--On a good sunny day, with battery bank "needed recharging" and/or heavy loads, I would expect a perfectly running system to be giving you at least 500 watts (great day, 700 watts or better)... (assuming you have 880 watts of solar panels, and the charge controller is in MPPT mode and trying to push as much current as possible in the battery bank--And the panels are pointing at the sun, no shade, no visible clouds/haze, clean panels, etc.). (Obviously, not being there and not having any way to know the amount of sun you are getting at any one time--This is all major guess work on my part).

Ah Charge Resetable-557.20 Ah
Heatsink temperature-40 C
--That sounds like the 37C "battery temperature" is really the Charge Controller temperature

Ah charge total -557.20 Ah
RTs Temperature-37 C[/QUOTE]

My two cents worth--I hope it was helpful.

-Bill

Re: What equipment needed for solar panels on FX 24v inverter

One Photowatt panel or one string of 4 panels in series?

Also, when you disconnect one string at a time, what does your array current become between the options (panel strings A, B, A+B in parallel).

In a way--look at this panels as sort of "D Cell" flashlight batteries in series/parallel. The panels are reasonably closely matched--so you are looking for large differences (high/low voltage in the panels somewhere, one string that is not providing enough/any current, etc.).

-Bill

Re: What equipment needed for solar panels on FX 24v inverter

If this is the correct Photowatt panel(s) (PDF), then you should be seeing somewhere around 65-80+ volts with 4 panels in series, full sun, using a digital volt meter (no loads on panels). Each panel should read nearly 21.7 volts Voc (Voltage open circuit) with a DMM.

If you are doing this measurement with the charge controller connected (MPPT?) then, you should be seeing something like 4x17.3volts=69.2 volts (or as low as 55 volts in hot weather).

Assuming everything is working and I understand your setup...

-Bill

Re: What equipment needed for solar panels on FX 24v inverter

Och... As Keith said, 75' at 25.8 amps will give you around 7.4 volt drop on 12 AWG wire:

• 7.4 volts * 25.8 amps = 191 watt losses from wiring run

Those voltage drops may account for most of the low Vmp you are seeing at the charge controller.

You have three choices now...

1. Leave as is... You are loosing power--but everything is working.
2. Go with 3 AWG or heavier wire for 2% or less voltage/power losses
3. Look at wiring the arrays into a ~100 VDC Vmp array (put 6 panels in series, then parallel the Photowatt/Astropower panels together):

Vmp~100 VDC, Imp = 12.9 amps. 75' run:

• 10 AWG wire, 12.9 amps, 75' run, => 2.3 volt drop or ~2.3% losses
• 12 AWG wire, 12.9 amps, 75' run, => 3.7 volt drop or ~3.7% losses

10 AWG would be great--Keeping your 12 AWG wire is not the worst solution out there to get you up and running and saving the cost of a run of 10 AWG wire.

#3 should work OK--Voc-cold at 14 degrees Fahrenheit will be around 145 volts... Not great, but probably better than you have right now. But--You are in Haiti--So what is your minimum temperature? 70F? That drops Voc-cold to 128 volts--perfect for your system.

-Bill

Re: What equipment needed for solar panels on FX 24v inverter

You cannot use the 4x photowatts in series... That gives you >152 volts (apparently) and will damage/void the warranty on most Solar Charge controllers (most have 150 VDC or less maximum input voltage).

If, I am understanding you correctly.

-Bill

Re: What equipment needed for solar panels on FX 24v inverter

The Photo Watts appear that they can be wired, internally in series or parallel output:

Photowatt
Pmp = 100 watts (105/110?)
Voc = 43.2/21.6 volts
Vmp = 34.4/17.2 volts ("24/12 volt jumper?)
Imp = 2.9/5.8 amps

So, you have several options on how to wire up your array (make best use of the total number of Photowatt's you wish to use).

And I am not quite sure what 3x3x3 wiring is? 3x3 series/parallel for 9 panels total?

How cold does it get where you are at? ~100 VDC Vmp is about as high as you should get if you have very cold weather.

-Bill