Comparing Power from Different Solar Panels on a 12 volt Array

[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

[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.

[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!

[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

[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]

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]

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,

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]

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