New solar panels

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Re: New solar panels

Postby crazyk » Fri Dec 30, 2016 6:06 am

Oh that's all good yeah I just saw it and thought it was interesting.

Am definetly looking at both those you mention I just have a few more questions to ask and will put them in the correct forum.
Last edited by Gordon-Loomberah on Fri Dec 30, 2016 10:48 am, edited 1 time in total.
Reason: removed unnecessary quoting
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Re: New solar panels

Postby crazyk » Thu Jan 05, 2017 3:40 pm

Ok, was going to start a new thread but thought I'd just continue this.

So my setup is going to consist of the following:

4 x AG12v100f Narada gel batteries (connected in Series for 48V system)
1 x 48v 1000w Pure wine wave inverter meanwell TS-1000-248C
2 x Suntech STP300-24/Ve Panels
1 x BlueSolar MPPT 150/35-MC4 (48V-35A) Charge controller

So just for me to clarify that i'm interpreting the specs of my system correctly

Panels are connected in Series
Max power generated = 438Watts (219W x 2)
Short circuit current = 7.14A (i've read to work on a max current produce of 1.25x this so 8.93A)
Max current = 8.93A
Open circuit voltage under NOCT = 81.2V (40.6 x 2)

So if I added another 2 panels would it still be just ok with this charge controller? the current is ok but the voltage is only 150V and 4 panels would produce 162.4V potentially. Should I be looking for a bigger unit with more voltage?
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Re: New solar panels

Postby davidg » Thu Jan 05, 2017 3:55 pm

crazyk wrote:2 x Suntech STP300-24/Ve Panels
1 x BlueSolar MPPT 150/35-MC4 (48V-35A) Charge controller
Panels are connected in Series
Max power generated = 438Watts (219W x 2)

Yes, 2 x panels in series if you add more they must be in parallel to the existing ones. If there 300Watt panels then a peak of approx 600watts actually, they may rarely produce that much but they will under certain circumstances.

crazyk wrote:So if I added another 2 panels would it still be just ok with this charge controller? the current is ok but the voltage is only 150V and 4 panels would produce 162.4V potentially. Should I be looking for a bigger unit with more voltage?

Yes fine to add more panels. 2 x panels in series (absolute maximum of 3 panels in series for this controller) for each string and then each string to be in parallel with the existing panels, you can have approx 1700watts of panels using a 48V battery pack with that controller.

There's no point in having more than 3 in series. DON'T use 4 in series it will exceed the maximum voltage the controller is rated for. If you windup with 3 strings of panels in parallel ensure you install correctly rated fuses/CB's in both the positive & negative of each string of panels (AS4509).
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Re: New solar panels

Postby crazyk » Thu Jan 05, 2017 4:52 pm

Thanks @davidg that helps me alot.

I'll start working on my system design now and i'll surely shoot back some questions as I progress.

EDIT: so david why would I choose to put my panels in series and not parallel?

EDIT #2: Also with the panels that I have, can I run a 24V battery setup?
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Re: New solar panels

Postby davidg » Thu Jan 05, 2017 8:52 pm

crazyk wrote:EDIT: so david why would I choose to put my panels in series and not parallel?

Actually you need them both in series and parallel if you want to max out power input.

MPPT DC charge controllers require a higher voltage than the highest voltage that will used to charge the batteries, temperature compensated. ie the highest voltage it will reach when its coldest for the area.

Otherwise the MPPT charge controller will not charge in those particular temp conditions.

crazyk wrote:EDIT #2: Also with the panels that I have, can I run a 24V battery setup?

Yes, but the number watts of PV will half to approx 850watts which is again approx 35A output of the MPPT charge controller.
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Re: New solar panels

Postby crazyk » Sat Jan 07, 2017 3:52 pm

davidg wrote:
Yes fine to add more panels. 2 x panels in series (absolute maximum of 3 panels in series for this controller) for each string and then each string to be in parallel with the existing panels, you can have approx 1700watts of panels using a 48V battery pack with that controller.

There's no point in having more than 3 in series. DON'T use 4 in series it will exceed the maximum voltage the controller is rated for. If you windup with 3 strings of panels in parallel ensure you install correctly rated fuses/CB's in both the positive & negative of each string of panels (AS4509).


So some clarification for me.

You mention that I can have approx 1700W with the 150/35 controller. I can't seem to work that out. I max out at 900W
My panels (ive rounded some numbers slightly):
300W
11A (factored up by 1.25)
45V

STRING # 1 : 3 panels in Series
900W
11A
135V

In order to max out the controller I can only have 3 strings resulting in the below, so how did you work out 1700W?

STRING # 1, 2, 3 ( Combined numbers )
900W
33A
135V
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Re: New solar panels

Postby APR » Sat Jan 07, 2017 5:40 pm

Image

While that gives you 1,800 watt, your charge controller will handle it OK.

EDIT... Into a 48v battery pack.
If you look at the Victron data sheet, they quote a maximum PV power of 2,000 watt for the 150/35....

https://www.victronenergy.com/upload/do ... -35-EN.pdf
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Re: New solar panels

Postby davidg » Sat Jan 07, 2017 8:53 pm

crazyk wrote:You mention that I can have approx 1700W with the 150/35 controller........

, so how did you work out 1700W?


35A x 48VDc = 1680W rounded up =1700W's :D

This is very quick and dirty calc one can use to ensure you roughly know where you are, typically a controller will handle a bit more. But it makes good rule of thumb so you know where can go for sure. So in the case of the panels assuming 300W's each using 2 x 300W = 600W x 3 strings = 1800W's which is a nice number to work with for that controller.
Off-grid Systems specialist- You could store Sun to use later- I Do!
SELECTRONIC SPMC-482 7.5kW, 8.2kW's of Arrays

with AC-Coupled Grid-Connect Inverters,
1100Ah 48V Bank

Auto Backup Genset
PVOutput Stats

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Re: New solar panels

Postby crazyk » Sat Jan 07, 2017 9:24 pm

Thanks guys.

My confusion came from assuming that the series panels added the wattage ie 600w.
When connected in parallel the wattage of all 3 strings did not add only the amperage did.
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Re: New solar panels

Postby crazyk » Sat Jan 07, 2017 9:32 pm

So can I add another question to the adobe.

A single one of my batteries has a max charging current of 25A.
If I decide one day to expand my array and the PV panels are putting out 33A what happens to the excess current?

I assume this controller will limit the charge current to the correct rate?
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