Beginner w/8 100W 12v panels in series to chg 2 LiPo4 12v batts: 60Amp MMPT or PWM for shade?

[El Tigre]

Buying 8 100W 12v HQST panels: https://www.amazon.com/gp/product/B095WRXB55/ref=ox_sc_act_title_2?smid=A2D22KZJD14Y8Y&psc=1
and looking to choose the right controller for my 2 100Ah LiPo4 batteries that are joined in parallel to power through my 12v sine wave inverter.
I’m hoping I can wire the eight 100W 12v panels in series (8*12v=96v) (100W/12v=8.3Amps).

I’m considering a Renogy Rover 20A 12V/24V Auto DC Input MPPT Solar Charge Controller $89.99​

https://www.amazon.com/Renogy-Charg...e+controller+lithium+mmpt,aps,151&sr=8-3&th=1

thinking that the 96v from the 8 panels in series (which barely falls below the controller’s “Max. PV Input Voltage: 100 VDC”) may work(?) However, I don’t expect more than 400W out of those 8-100W panels for much of the day and I need to run as much as 450 watts during the day so I may want to expand it later to include more panels..but this controller might not tolerate that higher voltage if I keep it all in series(?)

I have more trees than is ideal for solar. The HQST panels say they have a diode that helps the system get more power in partial shade situations.

1. Is this a wise configuration? Any alternative suggestions appreciated. I am a beginner.
2. Since I have as much as 30% wispy shade, should I just put this in parallel in the 1st place (and, if so, what is a good controller for that environment).
Thank you!

 

[Mattb4]

The specs for the HQST panels list Voc as being 21.6vDC. More likely you will see up to 23Voc from them. That means if you wire 8 in series your voltage would be 8 X 23 = 184vDC Too high for many SCC. Well over the 100vDC the Renogy lists for max PV.

Since you have shading issues you will want to run some panels in parallel. To stay under 100vDC you would likely go to 3S3P (need one more panel) arrangement. Now the thing that comes into play is adequate amperage carrying ability of wires and battery charge current.

 

[Pi Curio]

Is this a mobile or stationary application?

 

[El Tigre]

Stationary (on south roof of my house

 

[MisterSandals]

Buying 8 100W 12v HQST panels:

Any reason in particular you are choosing a lot of little panels?

Also
800W / 14V charging = 57A charging

You need a LOT bigger SCC than that 20A Renogy.

Do you have a budget or level of reliability in mind? If so, someone can recommend a 60A SCC.

 

[Pi Curio]

Unless you have a very strict space for mounting panels, bigger, residential panels will give you more bang for the buck.

That is, usually, a 300W-400W tier1 residential solar panel costs anything between 250-350$ depending on your location. A 2x 400W solar panel would give you the same wattage but would be more beneficial, especially if half-cut panels(duo panels). A lot easier to manage within SCC Voc and Isc limits, but also there would be a noticeable reduction in cost, cabling, and parts such as fuses, etc.

 

[El Tigre]

I saw a lot of 100w panels on Amazon but didn’t see any of those. Can you point me to some panels like you suggest?
Thanks!

 

[MisterSandals]

I saw a lot of 100w panels on Amazon but didn’t see any of those. Can you point me to some panels like you suggest?
Thanks!

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[Pi Curio]

Interestingly enough, I've managed to find what seems to be either used or manufacturer surplus stock per store description. Tier 1 panel! Note! possible dents and scratches.

Get two or more of them if you decide to get these. https://www.santansolar.com/product/used-jinko-400w-solar-panel/

With their Vmp and Isc, you can go for a parallel connection. Since these are duo panels, your panels will work independently of the other, and within each panel, each half will work independently of the other half if one is shaded.

Last but not least, Verify these panels are working upon delivery. I don't have any experience with that store.

If you go for two of these panels you'll save 200$ but get the same 800W of solar.

Note! To make these panels work, I would suggest getting a Victron SmartSolar MPPT 100/50 SCC. By saving 200$ on solar panels, you now can.

 

[Rednecktek]

Rule of thumb for calculating SCC size is you need 10a of SCC per 100w of panel for a 12v system. With your 800w of panels you're going to need an 80a MPPT controller to utilize all those panels.

Pro tip: If it has USB ports on it then it's a PWM controller lying to you.

 

[El Tigre]

Thank you for sending those links to larger panels. As to why I considered the little 100W panels, I don't have anyone to help me and some of those larger panels that were suggested would be heavy and unwieldy for me to wangle up a really tall ladder. And, once I add the freight on those big boys the cost isn't that different (and no warranty). Also, the 8 little 100W ones I was looking at:

https://www.amazon.com/gp/product/B095WRXB55/ref=ox_sc_act_title_2?smid=A2D22KZJD14Y8Y&th=1

would only cost me about $550 total delivered (with Amazon return rules and good warranty). The used/scratched ones I was shown above were great but I'm such a neophyte at this that going off the mainstream could be more a problem for me than one of you who are so much more experienced.

What if I just wired them in parallel? Suggested controller for that?
Thanks!!

 

[Pi Curio]

When connecting solar panels in series, the current remains the same but the voltage adds up.

If connecting in parallel, as you've suggested with all in parallel, each solar panel current adds up while the voltage remains the same.

As @Mattb4 previously said, with these 100W panels Voc and Isc, a 3S 3P is as high as you can go within reasonable Renogy 100/20 Voc Isc limit safety margin.

Last but not least, at the point where your array Isc is 65A, you'll have another set of challenges to address. MC4 connectors can tolerate up to 30A ish so it's not just about having a high enough SCC Isc limit.

 

[Black Pearl]

@El Tigre , I used to run 8pcs of 12v 100w panels on a Renogy rover 60 (mppt) with no issues. Wired them into 2 pairs (2 series 2 parallel).

That SCC is considered mid to lower tier, depending on who you ask of course. I've been running the same SCC for several years 24/7, without issue.

I eventually upgraded to a 24v system, using 16 PCs 100w panels. I use the same rover 60, as it can be used on 12-24-36-48volt systems. Glad I bought something that was ready for that upgrade back in the day, or I would've had to purchase another.

If I knew what I knew now (by binge reading here on this site), I likely would've done things differently (different components), but like you seem to imply, I did worry about other non related things like getting all my panels on the roof by myself. It was a chore, but I've seen others on this site do it with some back yard engineering.

 

[El Tigre]

I've been looking for a diagram of 3s3p since you recommenced it-- completely without success.
Is this (image attached) 2s2p? (if so how maybe I can figure it out (maybe 3 panels in each of 3 series groups and all 3 of those 3 series wired in parallel together). is that even close to right.

Even better, anybody have a diagram of a 3s3p setup?
Thanks!

 

[Rednecktek]

Yes, that is 2s2p, so you would do the same thing with 3s3p, same process just more panels.



The 3-in-1 splitters on the right would either need inline fuses or a combiner box. I would go with a simple 4 port combiner box that has your fuses, lightning protection, and disconnect in one box.

Also remember that with that much panel on a 12v system you're going to need an 80-100a MPPT controller to fully utilize those panels.

 

[Pi Curio]

If you would consider starting with 400w of solar now, and upgrading with more panels later, then investing in a capable SCC from the get-go would be advisable.

My suggestion would be to start with a Victron SmartSolar MPPT 100/50 with 4x HQST 100W panels in 2s2p.

Victron 100 50 @12 700W.

Since this is a stationary build, if one day you find it necessery to get more power, you can upgrade to 24v battery arrangement and have up to 1400W of solar with that SCC.

Its very easy to spend money on components that won't support future solar expansions, and will involve further expenses on new components that can.

 

[Mattb4]

I've been looking for a diagram of 3s3p since you recommenced it-- completely without success.
Is this (image attached) 2s2p? (if so how maybe I can figure it out (maybe 3 panels in each of 3 series groups and all 3 of those 3 series wired in parallel together). is that even close to right.

Even better, anybody have a diagram of a 3s3p setup?
Thanks!

No diagram needed. Simply connect 3 panels in series (pos of one panel to negative of next panel) to form a string. Do it again for another 3 panels and again for the final 3 panels. You now have 3 sets of panels with one positive and a negative output wire unconnected. Connect the 3 positives together and 3 negatives together (parallel) either with Y-connectors or more preferable a combiner box and there you go for an array.

Whether 2S2P (4 panel array) or 2S4P (8 panel array) it is easy to follow along.

 

[Rednecktek]

That SCC is considered mid to lower tier, depending on who you ask of course. I've been running the same SCC for several years 24/7, without issue.

There are many decent SCC's that will turn solar DC into battery DC, it doesn't have to be blue. Especially when you're trying to get a lot of panel on a 12v system.

As a few examples:

AmpInvt has an 80a unit with 150v PV input for about $280
EPEver is a well regarded brand with an 80a 150v PV input for about $335
Renogy has a 100a unit with 150v PV input for about $540

Or you can go with the Blue Team's offering of 85a at 150v PV input for about $700

Any of those units will have enough overhead on the PV input that you can run 4 panels in series (~88VoC) and put 2 strings in parallel to fully utilize those 8 panels. If you manage to fit more panels in each string later you can take those up to 6s2p really easily.

 

[Black Pearl]

There are many decent SCC's that will turn solar DC into battery DC, it doesn't have to be blue. Especially when you're trying to get a lot of panel on a 12v system.

Yeah, I have no issue with my Renogy SCC, nor my Renogy panels.

If there was one thing I wish I had known about prior to choosing a SCC that would likely serve me well over time, as I upgraded along the way, which seems to be very common, that would be a guaranteed to handle being over paneled SCC.

Seems Sigineer currently offers 2 SCC's at a nice price point, and they both can be over paneled as per their own literature.

As for the Renogy 60, all of the literature I have came across suggests over paneling is likely a big no no, but others may disagree with their literature. Me, I personally wouldn't chance it in the long run.

 

[Mattb4]

Deleted. Was for EU only.