Choosing a mppt controller

[Leonid]

I am planning to build a simple 12V solar system for my grandkids playhouse. I have a 265W Qcell panel with short circuit current 9.32A and open circuit voltage 38.52V. Would a 10A mppt controller work for my project? Any recommendations on make/model?
Thank you in advance,
Leonid

 

[Forbisher]

I am planning to build a simple 12V solar system for my grandkids playhouse. I have a 265W Qcell panel with short circuit current 9.32A and open circuit voltage 38.52V. Would a 10A mppt controller work for my project? Any recommendations on make/model?
Thank you in advance,
Leonid

265 watts at 12V would need a 20A SCC

10A will only produce about 130 watts max but maybe that is all you need?

Renogy or similar is on the low price end or get an Epever SCC.

What battery are you using?

 

[Leonid]

265 watts at 12V would need a 20A SCC

10A will only produce about 130 watts max but maybe that is all you need?

Renogy or similar is on the low price end or get an Epever SCC.

What battery are you using?

I have not chosen a battery yet, thinking of something like 20-50 Ah sealed. The system will be used mostly if not only for lighting. With modern 12V led I won’t need too much power.
I got confused with the max panel current of 9A. Is mppt able to produce more charge current to battery than the panel short circuit current? I have read recommendations to use formula dividing the panel Power to the battery voltage. Then I would need more than 20A. Wouldn’t 20A controller be overheated?
Thanks.

 

[hidiyguy]

Yes, MPPT can produce more amps than provided by the panel. 9.32A is the max your panel will produce at approx 28.4 Volts (265 watts/9.32 Amps). Your MPPT will convert that to your set charging current (say 13.8V) at up to 19 Amps or so (265 Watts/13.8V). MPPT chargers must be sized for both the input from the panel (check the specs to ensure it can handle both the open current volts and amps produced by your panel) and charging output in volts and amps. A 10A MPPT controller is saying it will charge at up to 10 Amps, and with your panel charging a 12V battery you need it to be able to charge at close to 20 Amps if your charging current is the notional 13.8V I mentioned (265Watts/13.8V =19.2 Amps).

 

[Hedges]

I have not chosen a battery yet, thinking of something like 20-50 Ah sealed. The system will be used mostly if not only for lighting. With modern 12V led I won’t need too much power.
I got confused with the max panel current of 9A. Is mppt able to produce more charge current to battery than the panel short circuit current? I have read recommendations to use formula dividing the panel Power to the battery voltage. Then I would need more than 20A. Wouldn’t 20A controller be overheated?
Thanks.

Any decent MPPT controller can be connected to PV array with extra watts, will limit its output current to what it can handle.

20Ah battery charged at 20A would be 1.0C, might not like that.
Look at the technical manual for the battery, find what "C" rate it prefers.
I have SunXtender, which actually asks for 0.2C minimum. They claim it can handle high inrush (like 5C!) but I programmed my system for exactly 0.2C

"Over paneling" and having charge controller limit charge current would give battery a constant current charge, until it reached target voltage and switched to constant voltage. That is probably better than having charge current vary as the sun rises. You should probably size it so it can replenish current used overnight by about 1:00 or 2:00 PM in winter; that will give it a few hours for absorption.

Make sure the charge controller has a temperature sensor for the battery. That is important to charge lead-acid properly.

 

[Northernchateau]

I own/run both a Rich Solar and Renogy 20amp controller. Both are easy to use, have a temp sensor and have been trouble free.
Just add a battery or two, circuit breaker and use the output from the Charge controller for the lights so it shuts down when the battery voltage drops. Keep the kids safe and put the battery in a plastic box and away from them.

Amazon.com : RICH SOLAR 20 Amp 12V/24V DC Input MPPT Solar Charge Controller with LCD Display Solar Panel Regulator for Gel Sealed Flooded and Lithium Battery Nagtive Ground : Garden & Outdoor

Amazon.com : RICH SOLAR 20 Amp 12V/24V DC Input MPPT Solar Charge Controller with LCD Display Solar Panel Regulator for Gel Sealed Flooded and Lithium Battery Nagtive Ground : Garden & Outdoor

www.amazon.com

 

[Leonid]

Is EPEVER 20A MPPT Charge Controller 12V 24V a good one? It is the only 20A controller currently available on Amazon Prime with 2-days delivery.

 

[Jasgeer]

I am planning to build a simple 12V solar system for my grandkids playhouse. I have a 265W Qcell panel with short circuit current 9.32A and open circuit voltage 38.52V. Would a 10A mppt controller work for my project? Any recommendations on make/model?
Thank you in advance,
Leonid

Honestly, for a playhouse I would consider a PWM to save money. If you find a good deal on a 10A MPPT then get it.

 

[Leonid]

Honestly, for a playhouse I would consider a PWM to save money. If you find a good deal on a 10A MPPT then get it.

I was advised by the other people that I need 20A for the 265W panel. Won't 10A charger fail or just limit charging by 10A? Thanks!

 

[NwCali]

With modern 12V led I won’t need too much power.

I use this battery: https://www.amazon.com/LiFePO4-Batt...qid=1625528056&sourceid=Mozilla-search&sr=8-3

and a PWM charge controller for my gate/gate light, which is motion activated, to what I believe is a 100 watt panel (might be more). Works great and will last a long time and cheap...

 

[rin67630]

I was advised by the other people that I need 20A for the 265W panel. Won't 10A charger fail or just limit charging by 10A? Thanks!

First, your panel will not always deliver its full power, to be honest say: almost never!

If you use a 10A SCC (which is plenty enough for 50Ah) you will be limited to 10A charging and have 80% over paneling.
But that is GOOD!
That means that you will have much better conditions to charge your battery on rainy days, when you panel will only deliver 10W.

 

[Hedges]

I have not chosen a battery yet, thinking of something like 20-50 Ah sealed.

20Ah battery charged at 20A would be 1.0C, might not like that.
Look at the technical manual for the battery, find what "C" rate it prefers.

I was advised by the other people that I need 20A for the 265W panel. Won't 10A charger fail or just limit charging by 10A? Thanks!

Whatever battery you select, determine the maximum and optimum charge current.
If a lead-acid battery, there is a charge current which will be optimum - lower current won't charge as effectively, and higher current will damage it.
So the best setup is over-paneled and has a charge controller that limits charging to optimum value.

Cheaper charge controllers aren't adjustable. If you select one that can tolerate over-paneling, then whatever output current it produces you can consider when selecting battery of a size for which that current is optimum.

 

[Leonid]

It is almost done. Thanks to everyone for your advice. I bought 16Ah LiFePo and 20A PWM. Small size and weight were what I liked.

 

[Hedges]

It is almost done. Thanks to everyone for your advice. I bought 16Ah LiFePo and 20A PWM. Small size and weight were what I liked.

Hmm, does data sheet for LiFePO4 say it can take charge at 1.25C?
But depending on how much PV and how oriented, peak current can be reduced.

Biggest concern with LiFePO4 is temperature when charging. It may have a BMS that disables charging below 0C, but with high charge rate you should set it to stop at a higher temperature. The idea is to make sure it will never charge at a rate (and temperature) which causes plating and loss of capacity.

 

[Leonid]

I believe the charger has everything “for dummies”:

About this item​

• INTELLIGENT REGULATOR : Compatible with 12v/24v batteries(SLD/FLD/GEL/LiFePO4/ternary lithium battery), this solar charge controller is auto resettable after disconnecting, also be auto-wakeup for lithium battery after setting battery type. Tracing the power faster and accurately with the 32 Bit High-Speed Master Chip.
• COMPREHENSIVE PROTECTION : With 6 protections, over-temperature, open-circuit, short-circuit, overload, reverse prevention circuit, reverse current protections. Certified by CE and RoHS. BougeRV PWM solar charge controller features with dual MOS circuit to prevent the reverse current and reduce the heat in operation. Maintain your battery all the time.
• CUSTOM YOUR SYSTEM : Various parameters adjustable to design the tailored system for you. Set the battery type, load operating mode, light control mode, and so on. Input and output will be realtime updated in the LCD display. Dual USB port, this PWM solar charge controller can power devices such as iPhone, iPad, and Android phones, maximum current can reach 2A.
• 

 

[Leonid]

I believe the charger has everything “for dummies”:

About this item​

• INTELLIGENT REGULATOR : Compatible with 12v/24v batteries(SLD/FLD/GEL/LiFePO4/ternary lithium battery), this solar charge controller is auto resettable after disconnecting, also be auto-wakeup for lithium battery after setting battery type. Tracing the power faster and accurately with the 32 Bit High-Speed Master Chip.
• COMPREHENSIVE PROTECTION : With 6 protections, over-temperature, open-circuit, short-circuit, overload, reverse prevention circuit, reverse current protections. Certified by CE and RoHS. BougeRV PWM solar charge controller features with dual MOS circuit to prevent the reverse current and reduce the heat in operation. Maintain your battery all the time.
• CUSTOM YOUR SYSTEM : Various parameters adjustable to design the tailored system for you. Set the battery type, load operating mode, light control mode, and so on. Input and output will be realtime updated in the LCD display. Dual USB port, this PWM solar charge controller can power devices such as iPhone, iPad, and Android phones, maximum current can reach 2A.
• View attachment 56118

I tested my setup. I discharged the battery to under 20% and placed the panel under the bright sun. The controller displayed up to 6A and went down to 0.1A in about 6 hrs. It looks like a very reasonable charging mode.