Wiring solar panels in series with three panels

[Vintage465]

So I am now messing with the idea of configuring my solar into a series set up. I currently have 2 each 150w Samlex panels. I am going to put a third matching panel up there.......that is all the realestate there is on the roof. So I've heard from a pretty "well read" friend of mine that I can wire two of the panels in series and the third one can just be wired in parallel................long as you use an MPPT controller. Thoughts on that idea?

Thanks

[Boon_Docker]

A second vote on the EPSolar Tracer controller. I have one and it is an excellent controller.

[BFL13]

The 40 amp Morningstar is about $500, while this one , that will do just as well IMO (several forum members have this one) is less than half that: eg (but there are many other vendors)

https://www.solargain.ca/product/epsolar-tracer-4210a-40-amp-mppt-charge-controller/

I have used the 20 amp version for my three 100w panel array, so I can vouch for the controller working ok. ( Tried them in series and in parallel using the same controller--made no difference in amps to the battery.) I now use it with a 255w panel, while a 30 amp PWM does the three 100s in parallel. That gets the same amps to the battery as did the MPPT controller--18.6 max high noon --Isc of one is 6.2)

EDIT--that was with panels tilted towards the high sun. Don't expect so many amps with the panels mounted flat on the roof unless you are parked at 23N Latitude on 21 June

[Vintage465]

pianotuna wrote:
Vintage465,

I was working with the numbers you posted. BFL13 has been helpful to many folks here and most of us only want to help folks out. Remember, the printed word doesn't allow for inflections--so please do listen calmly.

How did you decide on 450 watts of panels?

Will the install be fixed or do you wish to tilt (I'm firmly the fixed camp).

I decided on 450w of panels because I have 2 each Samlex 150w panels. I have real estate on the roof for one more matching panel. The two existing are fix as will the third one. It'll be the 3-150w, and probably a Morningstar PS-MPPT-40,charge controller to replace my Samlex 30a controller. The three 150's are non negotiable and the PS-MPPT-40 provides the flexibility to go either series or parallel without negative results. From the start, all I was looking for was:
1. Can one run on panel parallel to a pair in series. Answer came back "no". Perfect.
2. One poster provided the "daisy chain" example that clearly explained how you put 3 panels in series. Perfect.
3. I asked if the amps multiplied by 3 like the volts do. You answered no, as did other. Perfect.
4. That's all I needed.
5. Thank you for your patience.

[CA_Traveler]

For series you need another number:

Voc = 22.8*3 = 67.14V

You MPPT controller maximum input voltage rating must exceed 67V or it will let the smoke out.

AND the controller rating must exceed 67V FOR any temperature. There are calculators for this where you input the panel and your temperature range. Perhaps 80V+.

[pianotuna]

Vintage465,

I was working with the numbers you posted. BFL13 has been helpful to many folks here and most of us only want to help folks out. Remember, the printed word doesn't allow for inflections--so please do listen calmly.

How did you decide on 450 watts of panels?

Will the install be fixed or do you wish to tilt (I'm firmly the fixed camp).

[red31]

Theorize the result of panel heating (reduction in Vmp), light conditions and its angle of 'impact' (low light & low angle reduce amps). Also transforming inefficiency from 50v to batt v. Dynamic to say the least.

[Vintage465]

BFL13 wrote:
This is what you said,

"So I totally get the wiring now! This looks easy. Now lets talk amps. Each panel is 18.38v/8.82 amps. Do the amps triple like the voltage? Adding up to a theoretical high of 26.46 amps? Or do the amps stay an 8.82?"

Now that we have the link to the real specs, it is easy to see where you got mixed up, which in turn, made no sense to us.

So what do you want to know, now that is sorted out?

What I wanted to know is what "Pianotuna" posted:


"volts in series rise; amps in series do not rise

Amps in parallel rise; volts in parallel do not rise.

And watts stay the same.

Output from the panels wired in series in theory will be:


55.14 volts and 8.82 amps.

In real life, you may see 55.14 volts and 6 or 7 amps at solar noon.

In the morning you may see 55.14 volts and 1 or 2 amps."


All Good the minute he posted that.

Thanks,

[BFL13]

This is what you said,

"So I totally get the wiring now! This looks easy. Now lets talk amps. Each panel is 18.38v/8.82 amps. Do the amps triple like the voltage? Adding up to a theoretical high of 26.46 amps? Or do the amps stay an 8.82?"

Now that we have the link to the real specs, it is easy to see where you got mixed up, which in turn, made no sense to us.

So what do you want to know, now that is sorted out?

[Vintage465]

red31 wrote:

Vintage465 wrote:

BFL13 wrote:
A typical 150w panel has 17.24v for Vmp and 8.7a for Imp.

Wasting our time here until the OP gives us the real numbers.

Real numbers bro. Right from the Samlex Manual. I'm thinking you and your attitude should consider not assisting.

Hey Vintage, BFL13 knows the difference in IMP and ISC, note if you multiple the 'manual' Imp of 8.16 A by the Vmp of 18.38v ya get 150 watts. But you reported the Isc so maybe your attitude needs adjustment!!!!

What I reported is what the manual said. Each 150w panel can supply 18.38v. Each panel can supply 8.16a. Multiply 18.38 by three and you get 55.14v. My question was if the amps multiply by three or if they stay @ 8.16. Got my answer in one or more of the posts. Not sure where the "need real numbers" thing comes from....unless someone is thinking way farther down this project than I am at this time. I'm still in the "theory" stage prior to tearing things up.

[BFL13]

Found it--

http://www.samlexamerica.com/documents/manuals/11020-SRV-100-150-30A-0817_Hrez.pdf

Vmp-18.38 x Imp 8.16 = 150w

Voc - 22.38, Isc-8.82

[BFL13]

Vintage465 wrote:

BFL13 wrote:
A typical 150w panel has 17.24v for Vmp and 8.7a for Imp.

Wasting our time here until the OP gives us the real numbers.

Real numbers bro. Right from the Samlex Manual. I'm thinking you and your attitude should consider not assisting.

I would like to assist but you did say they are 150w panels, so what are they really? Please link the Samlex Manual to set me straight. Thanks.

[red31]

Vintage465 wrote:

BFL13 wrote:
A typical 150w panel has 17.24v for Vmp and 8.7a for Imp.

Wasting our time here until the OP gives us the real numbers.

Real numbers bro. Right from the Samlex Manual. I'm thinking you and your attitude should consider not assisting.

Hey Vintage, BFL13 knows the difference in IMP and ISC, note if you multiple the 'manual' Imp of 8.16 A by the Vmp of 18.38v ya get 150 watts. But you reported the Isc so maybe your attitude needs adjustment!!!!

[Vintage465]

BFL13 wrote:
A typical 150w panel has 17.24v for Vmp and 8.7a for Imp.

Wasting our time here until the OP gives us the real numbers.

Real numbers from the Samlex Manual. Those are what I have to work with right now.

[BFL13]

A typical 150w panel has 17.24v for Vmp and 8.7a for Imp.

Wasting our time here until the OP gives us the real numbers.