Multiple MTTP controller conundrum

jpd1009 · Newbie

Multiple MTTP controller conundrum

Whenarewethere · Guru

An MPPT on a solar panel is in the wrong place. It probably isn't an MPPT anyway even though they say it is. Bypass it & use the one next to the battery, where it should be.

Jaahn · Guru

jpd1009 wrote:
Hi,
I have a 250w panel with integrated mttp controller.
I am about to fit a DC-DC charger near the battries that also has a dedicated mppt solar input.
Optiona are...
1. Ignore the mppt on the DC-DC charger and keep using the solar panel untouched into the DC input to the battery.
2. De-commission the mppt controller on the solar panel and connect to the mppt on the DC-DC charger.
3. Leave the solar panel untouched and connect to the mppt on the DC-DC charger. In other words the current is running through two mppt controllers.
HELP

Hi welcome smile

As already said the MPPT regulator on the panel is most probably fake and just a PWM type. And in the wrong location too. So bypass it and option 2, feed the raw solar into the DC-DC charger. Possibly leave the reg there incase you want to use it for charging a battery or similar in an emergency(or not !). aww

Do not use one regulator to feed another as that will confuse them both.

Jaahn

jpd1009 · Newbie

Thanks for both replies, The solar panel one is definitely an MPPT one. I put it there in place of the pre-installed PWM.
I did this prior to buying the DC-DC charger.
I will run the one on the solar panel for now then when I get to installing the DC-DC charger I will decommission the MPPT on the solar panel and set up a solar input plug from the DC-DC charger.

Leshill · Veteran Member

I have a Redarc 25 w BC-DC charger installed and find the mttp charger in it is better than off the shelf mttp controllers that I also have. Also it is close to the battery.

I also put a red Anderson connector on the solar side of things.

I find the redarc system is tops.

Hylife · Guru

all charging on mine goes via the solar controller including the Andersen supply from the car and the projecter 240 charger.

The plus is I can see how much power the car AND solar combined put in on the drive.

-- Edited by Hylife on Wednesday 23rd of February 2022 10:00:52 PM

Peter_n_Margaret · Guru

Hylife wrote:
all charging on mine goes via the solar controller including the Andersen supply from the car and the projecter 240 charger.
The plus is I can see how much power the car AND solar combined put in on the drive.

The power from the 240V charger and the alternator need not go through the solar controller. It will likely overload it. It can go straight to the battery.

If you want to count it, that is best done via a shunt.

Cheers,

Peter

Hylife · Guru

Peter_n_Margaret wrote:
Hylife wrote:
all charging on mine goes via the solar controller including the Andersen supply from the car and the projecter 240 charger.
The plus is I can see how much power the car AND solar combined put in on the drive.

The power from the 240V charger and the alternator need not go through the solar controller. It will likely overload it. It can go straight to the battery.
If you want to count it, that is best done via a shunt.
Cheers,
Peter

Morningstar ProStar 40amp. No chance of overloading as is designed for PV systems up to 700W (12V) / 1400W (24V).

Because I have 200AH of LiFeP04, the controller actually limits the load placed on the 240V charger and on the vehicle alternator. LiFeP04 will happily suck up to 3C from the charging system if you let it.

Because it is programmable (manually or Modbus), I set up a proper charge profile to suit LiFePO4. Most that claim to be suitable for Lithium just label the Calcium profile as Lithium.