Dual MPPT chargers or single big controller? How to integrate multiple charge controllers into one system?

[Arikaree]

Newbie puzzle... am planning to install a basic 12v 400W system for my woodworking man-cave (was the old storage shed), based on the Classic 400 blue print.
Later, for redundancy and financing, I plan to expand that into a 24v 600-to-800W system, either as a single large array with large controller, or as parallel smaller arrays each with their own smaller controller. Something along the lines of the Off Grid King blue print.

Question: is it better to get a pair of (example) 40A mppt controllers, one now and one later on;
or, buy one 80A controller now?

I searched for info on how to marry 2 charge controllers into a single system, not having much luck finding how-to references.
I'm using Will's Mobile Solar Power book as my primary go-to reference. Awesome system diagrams!

Opinions requested, and/or where I can learn how to install 2 charge controllers to help my planning.

ps: have been looking at the Epever 40A, 60A and 80A mppt controllers; HQST 12v/100W mono panels, and AGM batts.

My thanks, from northern Colorado

 

[Reed Cole]

Install tip: Connect solar controllers in parallel to meet high power charging requirements

This installation tip was provided by Douglas Grubbs, applications engineer at Morningstar Corporation Large off-grid solar and battery backup PV systems

www.solarpowerworldonline.com

 

[Craig]

I have no problem with using 2 or more SCC connected to 1 battery. It actually has some advantages.
1. Redundancy if one goes out you still have a backup
2. You can have multiple arrays of PV facing in different directions if needed.

 

[Arikaree]

I have no problem with using 2 or more SCC connected to 1 battery. It actually has some advantages.
1. Redundancy if one goes out you still have a backup
2. You can have multiple arrays of PV facing in different directions if needed.

Craig,
1) I like the idea of a redundant system, however small it might be, something is better than nothing if only to keep the batts happy.
2) here in northern Colorado we have an abundance of solar, but that includes having panels aligned accordingly.
I am able to align panels to best fit the orbiting sun (ok, we orbit while the sun does not, got it, moving on.)
My goal is to take in as much solar as possible and fill my battery bank to the fullest.

Thanks for your feedback.

 

[Arikaree]

Install tip: Connect solar controllers in parallel to meet high power charging requirements

This installation tip was provided by Douglas Grubbs, applications engineer at Morningstar Corporation Large off-grid solar and battery backup PV systems

www.solarpowerworldonline.com

PERFECT!
I suspected this to be the case, but nothing beats confusion (me) like fact!

Am now proceeding to order my 400W system (panels and 40A Epever controller) as a base for my system.
Am confident that expanding this systemwith more of the same (Epever, HQST) will proceed without angst.

My thanks for helping us newbies, and me,

Arikaree
(Ah-rick-ah-rhee)

 

[Craig]

PERFECT!
I suspected this to be the case, but nothing beats confusion (me) like fact!

Am now proceeding to order my 400W system (panels and 40A Epever controller) as a base for my system.
Am confident that expanding this systemwith more of the same (Epever, HQST) will proceed without angst.

My thanks for helping us newbies, and me,

Arikaree
(Ah-rick-ah-rhee)

Check Craigslist for panels you may be able to get more watts for less bucks.

 

[DASH]

FYI, I have the 40AMP EPEVER controller. Give some thought about getting panels that may produce more amps then the controller can convert the power to the batteries but under what would damage the controller.

 

[Arikaree]

Install tip: Connect solar controllers in parallel to meet high power charging requirements

This installation tip was provided by Douglas Grubbs, applications engineer at Morningstar Corporation Large off-grid solar and battery backup PV systems

www.solarpowerworldonline.com

This is exactlky what I needed to find, Many Thanks

 

[Arikaree]

FYI, I have the 40AMP EPEVER controller. Give some thought about getting panels that may produce more amps then the controller can convert the power to the batteries but under what would damage the controller.

The monocrystaline HQSTs I'm looking at (12v 100W) run nominally 4.5A to 6A, per their data sheets.
The Epever SCC I'm considering is the 40A connected to 4 of the above HQSTs.
It should be capable of handling 6 of these HQSTs in parallel, more if in series?

Unless I'm missing something (quite possible), this looks to me like a compatible 12v setup.
I can also opt for 24V arrays (series).
Also seems workable per info from Will's book.
But I'd rather ask foolish questions than to burn the house down!

 

[Craig]

Your Epever can process a total of 480 watts at 12 volts or 960 Watts at 24 Volts. This is the battery voltage not the panel voltage. It can handle even more potential watts so the theory is to oversize the array just a little because you rarely get full production from your panels. My rule of thumb is if I get 80% I'm happy. Your panels are probably facing directly to the sun at the correct angle to get full power very infrequently if ever unless you are moving them somehow.
So with your current setup 6 of those 100 watt panels would probably be Ideal for each 40 amp MPPT

 

[Arikaree]

Your Epever can process a total of 480 watts at 12 volts or 960 Watts at 24 Volts. This is the battery voltage not the panel voltage. It can handle even more potential watts so the theory is to oversize the array just a little because you rarely get full production from your panels. My rule of thumb is if I get 80% I'm happy. Your panels are probably facing directly to the sun at the correct angle to get full power very infrequently if ever unless you are moving them somehow.
So with your current setup 6 of those 100 watt panels would probably be Ideal for each 40 amp MPPT

Sounds like I'm on the right track, I much appreciate your information.

As you mention above, individual panel alignment is my other challenge -- house is oriented SW/NE, no options. That, and some level redundancy, is how I came to focus on 2 separate and smaller arrays. The "morning" array (400w, 40A Epever) will face SE to South; the "afternoon" array will face South to SW. Best case at my latitude (40.25), I speculate reduced irradiance and reduced peak sun hours. With that reduced efficiency, good to know I can add a couple of extra panels to each array, and/or opt to 24v configurations (the most likely choice).

This further explains why cocktail hour here begins late afternoons, and not early evening.

Thanks again for the help!

 

[admsjas]

Check Craigslist for panels you may be able to get more watts for less bucks.

You can get SanTan used panels for less than $.025/watt. Check eBay for listings.
Caveat this is really only beneficial if you can do local pickup which happens to benefit me at the moment.

 

[DASH]

You can get SanTan used panels for less than $.025/watt. Check eBay for listings.
Caveat this is really only beneficial if you can do local pickup which happens to benefit me at the moment.

Back in November, I got 2 new 330 Watt Solar Panels from Santan Solar for $110 each. The original manufacturer labels were not there, but it was pretty easy to determine the manufacturer by looking at the specs of the panel (These are high quality panels). The warranty is limited (Can't remember, but it might be a year) The panels supposedly had cosmetic blemishes, but I never found any.

I believe Santan Solar warranties all their solar panels (including used), but it is limited, and not like the manufacturers 25 year warranties.

 

[admsjas]

Back in November, I got 2 new 330 Watt Solar Panels from Santan Solar for $110 each. The original manufacturer labels were not there, but it was pretty easy to determine the manufacturer by looking at the specs of the panel (These are high quality panels). The warranty is limited (Can't remember, but it might be a year) The panels supposedly had cosmetic blemishes, but I never found any.

I believe Santan Solar warranties all their solar panels (including used), but it is limited, and not like the manufacturers 25 year warranties.

You are correct, their warranty is a one year period. However if the OEM warranties it for a 25 year period and it’s a good quality panel are you concerned about life expectancy, minus abuse of course. Naturally the unknown is what period of time the panels were in use but if they perform close to what the specs on the back say I’m happy.

I currently have 17 265w panels and will be acquiring 5 more 270w panels next week. My current dilemma is how to integrate into what exactly I want to do. I foresee some questions coming up on this forum lol.

 

[DASH]

You are correct, their warranty is a one year period. However if the OEM warranties it for a 25 year period and it’s a good quality panel are you concerned about life expectancy, minus abuse of course. Naturally the unknown is what period of time the panels were in use but if they perform close to what the specs on the back say I’m happy.

I'm definitely not concerned about mine. They were new, they work well, comes from a major manufacturer, and the price I paid is definitely worth the very small gamble.

I wouldn't even be concerned to much about the used panels. I talked to Santan Solar about them, and they satisfied all my questions.

If planning on permits, or hooking up to the grid, insurance matters etc., I would look into the feasibility of using used and new no company panels (where the manufacturer no longer has any responsibility, and the codes (UL etc) may no longer apply).

 

[admsjas]

I believe that's why they sell them for off-grid use to alleviate themselves of liability. I'm trying to get off-grid anyways so any grid-tie option has no appeal to me anyway lol, to some it might though.

 

[MichaelK]

The monocrystaline HQSTs I'm looking at (12v 100W) run nominally 4.5A to 6A, per their data sheets.
The Epever SCC I'm considering is the 40A connected to 4 of the above HQSTs.
It should be capable of handling 6 of these HQSTs in parallel, more if in series?

No, a 6S1P configuration will NOT work with this panel/controller combination. These HQST panels have an open circuit voltage of 21.3 (Voc). Six of those in series would be producing 21.3 X 6 =127.8VDC. Since the Epever 40A has on Voc limit of 100VDC, this configuration can damage the controller. At -20F even 4 of these panels will exceed 100V. A winter low of <-20F seems likely in a place like northern Colorado.

You could safely wire them in a 3S2P configuration. Then you'd get ~63Voc (54Vmp) and 11 amps of current.

 

[bobs]

Install tip: Connect solar controllers in parallel to meet high power charging requirements

This installation tip was provided by Douglas Grubbs, applications engineer at Morningstar Corporation Large off-grid solar and battery backup PV systems

www.solarpowerworldonline.com

very basic ? where do i hook the wires? do i twist the two + wires together and the - together and tie these to the + & - battery post?

 

[pollenface]

You're going to want to hook the wires from the controllers to the batteries.

You can twist them or solder them. I prefer solder personally.

 

[bobs]

thank you