MPPT controller recommendations

[beemerphile1]

I purchased four of these 100 watt panels from Home Depot.
https://www.homedepot.com/p/Grape-Solar-100-Watt-Polycrystalline-Solar-Panel-for-RV-s-Boats-and-12-V...
I figured at 89 cents per watt and free shipping it was time to buy.

Now I need the other necessary components such as a 40 amp or larger MPPT controller, wiring, and mounting.

Primarily I am looking for controller recommendations as I am overwhelmed with all the available options.

Any advice on wiring and mounts would also be appreciated.

Two panels will be mounted in one area and two panels in another. Because of that I am thinking each pair in series and the two pairs in parallel unless there is good reason not to do so.

I currently use four gel batteries for 300AH but might be switching to four golf car batteries for a total of 440AH.

[red31]

Don't forget heat with 12v panels, it can get hot enough that having the extra cells/mppt let's the panel operate at higher power. Clouds as I measured 120F/50C (31C ambient), I'm sure the back of the panel was hotter in sun.

Grape 40A BT PWM controller $55
https://www.homedepot.com/p/Grape-Solar-40-Amp-PWM-Solar-Charge-Controller-with-Bluetooth-GS-PWM-40B...

was able to change boost and float voltages, had difficulty changing them back, will take some testing to figure out what works 100% of the time.

[ktmrfs]

BFL13 wrote:
"One exception is portable panels with a long run, (100ft+) then series panels with MPPT will reduce IR loss"

Depends. You then have lower controller efficiency by going 24-12 instead of 12-12. If the efficiency difference is 3%, that counters a lot of wire loss.

good point. run power loss is related to current squared, so one needs to compute the I^2*R loss vs. controller efficiency loss. On reasonably short good wire size, parallel 12V panels likely win.

I did some data collecting a year or so ago looking at charging current series vs. parallel with a midnite solar Kid using 3 160W panels and 100Ft of 30A RV cable with ground paralleled with one side. At 100ft with my controller, series gave an advantage, 25A in parallel vs. 8A in series. But the advantage was less than 10% IIRC A few amps at most in charging current.

Now that 24V panels seem to be noticeably less expensive than 12V the quandry is.

should I go with PWM and spend the extra a MPPT controller would cost on extra 12V panels, Or should I go with 24V panels and MPPT. which ends up less expensive?

[MrWizard]

I was there this past Thursday (2) days ago
The monitor inside the RV showed 14.73v charging , 1.3 amps
100%, full

I did not use the app to check the charge controller

The monitor inside tracks Watts, amps, amp hrs, and SOC

If i can remember, I'll check everything using the tablet app, when i go they next Thursday

[BFL13]

"One exception is portable panels with a long run, (100ft+) then series panels with MPPT will reduce IR loss"

Depends. You then have lower controller efficiency by going 24-12 instead of 12-12. If the efficiency difference is 3%, that counters a lot of wire loss.

[ktmrfs]

If you really want MPPT look at the midnight solar Kid. But in reality, a midnite solar BRAT PWM controller or any other PWM controller gives up very little on 12V panels to MPPT. Get a PWM controller and spend the difference on another panel.

years ago when panels were expensive, or today if you use 24V panels, MPPT controllers made lots of sense. Today, not near as much.

On exception is portable panels with a long run, (100ft+) then series panels with MPPT will reduce IR loss.

[westend]

I'd like to know which model Grape controllers you folks are using. That is really good value if there are settings control for voltage.

I have a Morningstar MPPT-15 and the controller interfaces with the Msview software perfectly. I hook up the laptop and can see in real time the harvest and draw of the 12V system, besides the variable set points. It also has temp compensation for the batteries and I've confirmed the accuracy of that. IMO, Morningstar makes good MPPT solar controllers but price is reflected.

I'd also think a 30 amp controller will get the job done. Most MPPT controllers shed any amperage above their maximum threshold. I've seen close to 16 amps with the MPPT-15.

If you're maintaining gel cell batteries, their charging requirements are in a narrow configuration. You'll want a controller with variable set points for the charging current.

[red31]

MrWizard wrote:

i'll get some screen captures from my tablet running the APP

If I do a READ after SETting different voltages they return to default. So I can get screen shots with almost any voltage.
I monitor the min/max voltage graph, touching the data pts reveals a 'bubble' with voltage, the scale is not marked.

[MrWizard]

i disagree
i have that controller and you 'can' change voltage settings
i set the charge voltage at 14.8v

that controller is in the safari
(provided i remember)
next week when i am there i will take a few pictures?
i'll get some screen captures from my tablet running the APP

[red31]

https://www.amazon.com/Victron-SmartSolar-Charge-Controller-Bluetooth/dp/B073ZJ3L13
MPPT Calculator Excel sheet
https://www.victronenergy.com/upload/software/VE-MPPT-Calc-2_7.xlsx

For $55 go with the grape 40A-BT all in parallel, do not expect to adjust voltages

From grape
Thanks for getting in touch. The charging voltages cannot be changed on this controller. The app enables other settings to be altered (such as EQ cycle time, battery capacity, etc.), but the charging voltages are tied to the specific battery type settings. The only voltage settings that can be adjusted are the two "over-discharge" values. Please let me know if you have any other questions.

Gel set pts are 14.2 abs and 13.8 float

Extension wire with MC4 on each end or one end bare and parallel connectors https://www.renogy.com/products/wires/

[jharrell]

pianotuna wrote:
Hi Time2roll,

The Morningstar MPPT 60 does have some advantages--it is essentially three controllers "stacked" together, so it is more efficient at low amperage than the 45.

I made the mistake of only getting a 30 amp controller, that meant upgrading meant buying either an additional controller--or buying a larger one. I've not done either because of the cost.

I second the Morningstar MPPT 60, has been flawless, no fans, extremely efficient, has built in ethernet if you want monitor remotely and headroom to expand. Buy once cry once.

[TUCQUALA]

Look at the EPSolar (EPEver) 40A MPPT controllers. Really nice units with lots of adjustments. And not out of line on price for most of us!!!

https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/29522581/srt/pa/pging/1/page/1.cfm

[MrWizard]

my '2 cents' the grape solar 40 amp PWM controller
wire the panels in parallel
its a great controller
fully configurable for all voltage points
even time in bulk
and voltage recover/restart points
and it has bluetooth built in and run the app on your phone or tablet
to control settings and monitor the panels
and a fantastic value at approx $50-$60

[brulaz]

time2roll wrote:

pianotuna wrote:
Minimum standard for the controller would have adjustable voltage set points and a temperature probe on the battery bank.

I also recommend a controller that automatically adjusts absorption time based on charge level.

Now that gets pricey. But the Bogart PWM SC-2030 combo with it's Trimetric Ah meter and shunt is nice and prolly the cheapest with this feature. The idea here is to limit over-charging your lead acids. But not sure how much of a problem that really is. Under-charging seems to be a bigger problem.

As for a relatively cheap MPPT controller with temp probe and adjustable everything, I'm happy with my EpSolar Tracer.

[time2roll]

pianotuna wrote:
Minimum standard for the controller would have adjustable voltage set points and a temperature probe on the battery bank.

I also recommend a controller that automatically adjusts absorption time based on charge level.