Dc dc converter

Discussion about the MX60 Charge Controller

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Mattb1
Forum Junior Member
Posts: 2
Joined: Wed Oct 24, 2018 10:59 pm
My RE system: Flexmax 60
1kw solar array
Fx2400 inverter
24kwh 24v flooded lead acid battery pack
1 mate
4kw petrol generator which i have rigged up for auto start

Dc dc converter

Post by Mattb1 »

Ok i have moved into a new house that is totally off grid and i am working to improve the system.

The budget is very small so up grading panels is not really an option.

My question is can i fit cheap off the shelf dc dc converter to each panel and then feed this more constant voltage to my charge controller.

Tge reasoning behind this is to try and reduce some of the volt drop in the cables.

Any thoughts would be greatly helpful
jbakker
Forum Guru
Posts: 227
Joined: Fri Feb 23, 2018 5:47 am
My RE system: 2 VFX3648 Inverters 1 FM60 150VDC Charge Controllers Mate3 3.4 KW of panels 15kw JC Onan NG Generator made in 1975.
1 Midnite Classic 150, FNDC. I have the Volt battery but it's not being used.
Now using 48 volt 425 AH Narada Lithium cells and 1 250 Amp 48 VOLT DALY BMS.
Location: Goderich Ontario Canada

Re: Dc dc converter

Post by jbakker »

Well your charge controller is a DC to DC device.
It takes the voltage of your panels and converts it to the 24 volts for your battery bank.
So installing Dc to DC converter at the panels does not make much sense to me.
Other people smarter than me may have more info on that.
How far away are the panels?
How are they wired?
What voltage and wattage are your panels?
Is the system not performing well?
What batteries are you using?
What are your absorb and float settings?
The more info you give us the better we will be able to help.
Mike Curran
Forum Emperor
Posts: 2271
Joined: Sat Aug 28, 2004 6:28 pm
My RE system: Outback - Garage roof:
- 8 (2x4) Evergreen 180's into one FM80 (2007/2020 - replaced MX60)
- 6 (2×3) ALEO S79-300's into one FM80 (2017)
- 2 grid-tied VFXR3524A-01's series stacked, replaced GVFX's (2020)
- 12 Surrette/Rolls 2V x 1766Ah (2007)
- Hub10.3, Mate3s, FNDC, RTS. Tigo ES maximizers on each PV module.

Westinghouse Solar - Barn roof: (2012)
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied

Outback Skybox - Barn roof: (2019)
- 14 Talesun 275W in series (DC array input to SB inverter/charger)
- 3 SimpliPhi 3.8 batteries, 48V, 225Ah total
- AC coupled input from 14 Talesun 275W, Enphase M215 microinverters

All self-designed and self-installed
Location: Chagrin Falls, Ohio

Re: Dc dc converter

Post by Mike Curran »

As jbakker says, more info would help. But assuming your 1kw array is comprised of 4, 250W panels, it seems doubtful you can find "cheap" DC-DC converters sized for that much power, that would be more economical than simply adding a couple more panels. Only complication would be making sure the added panels are a good match to your existing ones, otherwise your Flexmax 60 won't do a good job finding the max power point of your array.

And unless your array is located far away from your charge controller and/or the connecting cables are too small, there won't be a lot to gain by (I'm assuming here) raising the voltage being delivered to your CC with DC-DC converters.

Again (more info), how are your panels wired? You might be able to reduce wire losses by putting more panels in series to get a higher output voltage, if the existing setup is not optimal (e.g., all panels are wired in parallel).

Just my 2 cents' worth. - Mike
https://smart.tigoenergy.com/p/pZXn7SZQyO45?date=2021-04-19
https://enlighten.enphaseenergy.com/public/systems/Hctc107221
Mattb1
Forum Junior Member
Posts: 2
Joined: Wed Oct 24, 2018 10:59 pm
My RE system: Flexmax 60
1kw solar array
Fx2400 inverter
24kwh 24v flooded lead acid battery pack
1 mate
4kw petrol generator which i have rigged up for auto start

Re: Dc dc converter

Post by Mattb1 »

Ok yes me and re information

Ok i have 8 160w panels wired in a series parallel configuration so 4 panels in each string.

Cable look like 4 mm2 and cable run is approximately 40m

My panels are very old bp solar so be quite difficult to get anything to match, and from outbacks calculator i can only add 1 more panel to each string if i could source them.
SandyP
Forum Guru
Posts: 469
Joined: Tue Jun 21, 2011 4:44 am
My RE system: 8 x 190W 24V Suntech panels (4 strings of 2) July 2011
4 x 325W 24V Suntech panels (2 strings of 2) added Sept2018
Mate2
Outback FM60 MPPT (max output lowered to 55amps)
12 x 2V Hoppecke GEL 612 Ah C24 - 24V System (June 2011)
Outback VFX3024 Inverter/Charger
Victron BMV-602s
Honda 5.5kW Genset
Location: Victoria, Australia

Re: Dc dc converter

Post by SandyP »

Also, what voltage do you see as the normal input voltage into the FM60 and the peak voltage (Vp on the summary screen of the FM60)?
And, what is the normal (daily) peak amps (Ap on the day summary screen of the FM60)you see that go to the battery bank?

With sub optimal panel orientation, derating with the ageing of the panels, and normal operating conditions lowering the panel output in many cases you can add additional panels (ie a new string) without overloading the charge controller.
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