Dc dc converter

Discussion about the MX60 Charge Controller

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Dc dc converter

Postby Mattb1 on Wed Oct 24, 2018 11:09 pm

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
Mattb1
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Re: Dc dc converter

Postby jbakker on Thu Oct 25, 2018 7:26 am

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.
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Re: Dc dc converter

Postby Mike Curran on Thu Oct 25, 2018 9:52 am

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
http://www.tigoenergy.com/site.php?95b2dca2-ca6c
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Re: Dc dc converter

Postby Mattb1 on Thu Oct 25, 2018 11:57 pm

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.
Mattb1
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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

Postby SandyP on Fri Oct 26, 2018 2:50 am

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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