Comparing Power from Different Solar Panels on a 12 volt Array

[Mike90250]

I feel the best power to the batteries will result from my suggestion, which should not confuse the MPPT

[BajaBob]

HI Mike,

If the MPPT proves to not be confused by that configuration, which proposal is the best for supplying the most power to the batteries ?

Thanks very much for your help !

BajaBob

[Mike90250]

Mixing 2, series 19V panels and then paralleling 38V panels, may confuse the MPPT. But the way I suggest, the MPPT will not be confused, both strings will be matched.

[BajaBob]

Hi Mike,

I'd be happy to rearrange any of the info into an easier configuration to read.
How would be best for that to be ?
To make it most clearly stated and simple to read and compare ?

I'll also check with Outback, to see if that original configuration by our technician would confuse the MPPT charge controller.

If that setup didn't confuse the MPPT, which proposal- between yours and the original proposal- would provide the most power ?

Thanks much to you and all for your help with our problem !

BajaBob
__
The system is 12 volt:
Outback MX60 PV MPPT (Maximum Power Point Tracking) Charge Controller,
Trace Inverter model DR2412 (2400 watt) Modified Sine Wave,
Samlex Inverter Full Sine Wave PST-60S-12A 600 Watt Pure Sine Wave Inverter, 12VDC-120VAC,
2 Kyocera 130 W Solar Panels 12 volt
6 Crown L16 batteries

And-
Looking for the best way to include 2 BP3230T 230 watt solar panels into the system.

Specs on the two types of panels are:

Specs for Kyocera KC130TM 130:

Electrical Specifications:

Maximum Power: 130 watts
Tolerance: +10%/-5%
Maximum Power Voltage: 17.6 volts
Maximum Power Current: 7.39 amps
Open Circuit Voltage: 21.9 Voc
Short-circuit Current: 8.02 amps

Max. System Voltage (12/24/48V Nominal): 600 volts
Series Over-current Protection: 15 amps
__

Specs for the BP3230T 230 watts panel are:

(Guessing their terminology equates to. If I've got that wrong, pleasee let me know.)

Electrical Specifications:

Maximum Power: 230 watts
Tolerance: +5%/-3%
Maximum Power Voltage: 29.1 volts
Maximum Power Current: 7.90 amps
Open Circuit Voltage: 36.7 Voc
Short-circuit Current: 8.40 amps

Max. System Voltage (12/24/48V Nominal): 1000 volts
Series Over-current Protection: 20 amps

[Mike90250]

I had to struggle with the way the numbers and specs were spread all over the place. Wiring the way I suggest, will be pretty efficient, if you only have the 1 controller.

Mixing 2, series 19V panels and then paralleling 38V panels, may confuse the MPPT. But the way I suggest, the MPPT will not be confused, both strings will be matched.

[BajaBob]

Additionally, the location of this system is in sunny Baja, Mexico. A couple of hundred miles from the border. It's not far from the sea there, so it is very temperate. Days average 65

[BajaBob]

Hi Mike,

Thank you very much for your thoughtful and extensive response.

Is this original proposal incorrect in it's calculations
and expected power result then ?

What would be the difference between your proposal
and this quoted proposal:

In the math and power producing function ?

Factoring in the same discount 20% off the panel output
and environmental variables from both proposals ?


Thank you very much for thinking about our problem !

BajaBob

This is the proposal quote that I posted:

I recommend this for the KC130s (series connecton) and parallel wire two BP3230Ts, keep the voltage at 36.7. Doing so would create a voltage that is almost equal for the two two different makes.


This arrangement would produce 720 watts/hr of solar energy for the battery bank. That would make them happy!

[Mike90250]

.... I recommend this for the KC130s (series connecton) and parallel wire two BP3230Ts, keep the voltage at 36.7. Doing so would create a voltage that is almost equal for the two two different makes........

Not sure who is being quoted there, but the 36.7 is open ckt voltage, not power voltage.

And whoever did all the math there, forgot to discount 20% off the panel output, because they are not in a lab test, but out in the field.

You will find in cold weather (less than 60F), you will get more power, as the panels run cooler and put out more. Generally offset by a worse sun angle, unless you have some snow helping reflect light to the panels.

[Mike90250]

You have one MPPT controller.

2 panels
Maximum Power: 130 watts
Tolerance: +10%/-5%
Maximum Power Voltage: 17.6 volts
Maximum Power Current: 7.39 amps
Open Circuit Voltage: 21.9 Voc
Short-circuit Current: 8.02 amps

&

2 panels
Maximum Power: 230 watts
Tolerance: +5%/-3%
Maximum Power Voltage: 29.1 volts
Maximum Power Current: 7.90 amps
Open Circuit Voltage: 36.7 Voc
Short-circuit Current: 8.40 amps

Am I right ?


I would put on old panel, and one new panel in series, and parallel that with another old & new.

17.6 volts @ 7.39 amps & 29.1 volts @ 7.90 amps yeilds 46.7v @ 345 watts each string, or nearly 700W -20% real life losses = 550w into the batteries ! ( @ 15V = 36amps

adding up nameplate and deducting 20% gives 576 watts So you only loose 26 watts in the amp mis-match. Or you could buy another $600 charge controller

[BajaBob]

Hi Dave,

Thanks for your response. I've been involved with the solar power system in Baja for about 6 years, but I'm no expert. Our trusted technician has recommended this setup, but I've gotten mixed reviews on it from various knowledgeable sources- so I am compelled to understand more of the situation before Green Lighting it.

I'm wondering if these separate Series/Parallel wired panels will make for the voltage being indeed higher?

Or if what you have said is indeed true, and there is no way to get the higher voltages from the 230 watt panels without a second charge controller ?

All info on this greatly appreciated !

BajaBob

This, again, is that recommended setup for these two types of panels on our 12 volt system:

I recommend adding at least two more big solar panels, minimal. Something like the BP3230T (230 watts each = 460 watts, @ 8 amps each = 16 amps), plus the two Kyocera KC130TM 130s, would deliver approximately 32 amps of energy

The two KC130s are delivering a total of 15 amps to the batteries.


The remedy is to wire the two of them in series to produce double the voltage or 34 volts, that will do the job. Fortunately you have the mighty fine Outback MX60 MPPT charge controller that is capable of bringing in up to 150 vdc from the solar array; higher is better, more efficient.


I recommend this for the KC130s (series connecton) and parallel wire two BP3230Ts, keep the voltage at 36.7. Doing so would create a voltage that is almost equal for the two two different makes.


This arrangement would produce 720 watts/hr of solar energy for the battery bank. That would make them happy!

And this is the current system:

The system is 12 volt:
Outback MX60 PV MPPT (Maximum Power Point Tracking) Charge Controller,
Trace Inverter model DR2412 (2400 watt) Modified Sine Wave,
Samlex Inverter Full Sine Wave PST-60S-12A 600 Watt Pure Sine Wave Inverter, 12VDC-120VAC,
2 Kyocera 130 W Solar Panels 12 volt
6 Crown L16 batteries

[zdavesf]

Like Mike and others have already mentioned if you parallel the old panels with the new ones and use one controller you will not be using the full potential of the new panels. The there max voltage on the new panel is 29.1 and the old panels is 17.6. meaning that the new panels will only work at 17.6 volts a loss of 11.5v (40%) which if using a MPPT controller (assuming 100% which its not) your new 230watt panels would really only be around 138 Watts!!

leave the existing setup as it and buy a new MPPT charge controller for the new panels and attach it to the existing battery bank (parallel the outputs of the charge controllers.)


at least that's the way i see it, someone else jump in if I got lost... I too am still new to the whole solar world

Dave

[BajaBob]

So to put these both in the same posting for easier comparison:

Specs for Kyocera KC130TM 130:

Electrical Specifications:

Maximum Power: 130 watts
Tolerance: +10%/-5%
Maximum Power Voltage: 17.6 volts
Maximum Power Current: 7.39 amps
Open Circuit Voltage: 21.9 Voc
Short-circuit Current: 8.02 amps

Max. System Voltage (12/24/48V Nominal): 600 volts
Series Over-current Protection: 15 amps
__

Specs for the BP3230T 230 watts panel are:

(Guessing their terminology equates to. If I've got that wrong, pleasee let me know.)

Electrical Specifications:

Maximum Power: 230 watts
Tolerance: +5%/-3%
Maximum Power Voltage: 29.1 volts
Maximum Power Current: 7.90 amps
Open Circuit Voltage: 36.7 Voc
Short-circuit Current: 8.40 amps

Max. System Voltage (12/24/48V Nominal): 1000 volts
Series Over-current Protection: 20 amps

[BajaBob]

Whoops!
That image didn't post.
And I don't have a font that can handle their terms . . .

Here's the website where those BP3230T 230 watts solar panel specs can be viewed:

http://www.posharp.com/bp3230t-solar-panel-from-bp-solar_p1054696977d.aspx

Thanks much for your time !

BajaBob

[BajaBob]

Thanks much for your response !

With these specs below, will it perform as proposed ?

Thanks again !
BajaBob
__

Specs for Kyocera KC130TM 130:

Electrical Specifications:
Maximum Power: 130 watts
Tolerance: +10%/-5%
Maximum Power Voltage: 17.6 volts
Maximum Power Current: 7.39 amps
Open Circuit Voltage: 21.9 Voc
Short-circuit Current: 8.02 amps

Max. System Voltage (12/24/48V Nominal): 600 volts
Series Over-current Protection: 15 amps


Specs for the BP3230T 230 watts panel are:

[Mike90250]

Thanks for the info !

Any thoughts about this latest proposal ?

BajaBob
___

The remedy is to wire the two of them in series to produce double the voltage or 34 volts, that will do the job. Fortunately you have the mighty fine Outback MX60 MPPT charge controller that is capable of bringing in up to 150 vdc from the solar array; higher is better, more efficient.


I recommend this for the KC130s (series connecton) and parallel wire two BP3230Ts, keep the voltage at 36.7. Doing so would create a voltage that is almost equal for the two two different makes.


This arrangement would produce 720 watts/hr of solar energy for the battery bank. That would make them happy!

I don't knw the specs on the panels, but as long as the series panels are within 10% of the same amps, and the parallel panels/strings are also within 10% of Vpmax, your MPPT controller will be happy.