Connecting 280W of panels to BlueSolar 75/15

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m1ck asked Mar 10, '21

Connecting 280W of panels to BlueSolar 75/15

I have a BlueSolar MPPT 75/15.

On the roof, I already have two photovoltaic panels (Kyocera KD140GH-2PU) of 12v, 140W each. They are connected in parallel. In their specs:

At 1000 W/ m² (STC)*

Maximum Power [W] 140

Maximum System Voltage [V] 1000

Maximum Power Voltage [V] 17.7

Maximum Power Current [A] 7.91

Open Circuit Voltage (VOC) [V] 22.1

Short Circuit Current (ISC) [A] 8.68

Efficiency [%] 13.9

At 800 W/ m² (NO CT)**

Maximum Power [W] 101

Maximum Power Voltage [V] 16.0

Maximum Power Current [A] 6.33

Open Circuit Voltage (VOC) [V] 20.2

Short Circuit Current (ISC) [A] 7.03

NOCT [°C] 45

Can I directly connect these panels as they are to this charge controller?

Solar Panel mppt charging

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glenn748 commented · Mar 11, 2021 at 04:05 AM

The battery can be kept from over release by interfacing all heaps to the charging outlet.

UPSers

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Answer 1 · 2021-03-10T14:52:46Z

seb71 answered · Mar 10, 2021 at 02:52 PM

They have different voltages. So not a good idea to connect them in parallel.

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m1ck commented · Mar 10, 2021 at 03:05 PM

They have exactly the same voltage, as they both are the same maker and model. They have been working for years in parallel with an older PWM charge controller. Are you comparing 'at 1000 W/m2' versus 'at 800 W/m2' values?

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seb71 m1ck commented · Mar 10, 2021 at 03:12 PM

Yeah, I thought you have two different panels.

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seb71 m1ck commented · Mar 10, 2021 at 03:23 PM

You will never get 280W into the battery (that charger has a 15A current limit into the battery), but in cloudy days an oversized PV array will help.

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seb71 seb71 commented · Mar 10, 2021 at 03:24 PM

I am assuming you have a 12V battery.

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Answer 2 · 2021-03-10T15:10:24Z

Stefanie (Victron Energy Staff) answered · Mar 10, 2021 at 03:10 PM

Hi @M1CK,

yes you can connect them to the MPPT controller. They are a little low on maximum power voltage. Be aware that the MPPT to start charging requires a voltage of at least 5V above battery voltage. But when you connect them in series, it should be no problem.

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Answer 3 · 2021-03-10T15:29:57Z

offtaps answered · Mar 10, 2021 at 03:29 PM

You should not connect them in parallel as Isc of such an array is greater than the maxi allowed for the 75/15 (15A)

Just connect them in series.

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Answer 4 · 2021-03-10T16:10:37Z

spanner answered · Mar 10, 2021 at 04:10 PM

The perfect world calculation is (140w x 2) = 280w / voltage (12v) = 23 Amps - in reality you wont get that output of 280w as the spec you provided is 6.33A. As above the VOC of your panels is 20.2 x 2 - the mppt will go up to 75v. So conclusion is YES ;-)

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seb71 commented · Mar 10, 2021 at 05:18 PM

For Standard Test Conditions:

Isc = 8.68 A

Voc = 22.1 V

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