Going Solar on the GU wagon

[Brissieboy]

DC electrons don't like being pushed through long solid metals (larger strands).

Actually the individual conductor size has no impact for DC or low frequencies. It only effects the flexibility or ability to withstand movement or vibration.
It is only with high frequencies where 'skin effect' occurs which make the conductors appear electrically smaller and multiple small strands or better than fewer large ones.
It is primarily the overall size or cross-sectional area, but also flexibility, that is important here.

[Yeti's Beast]

So basically use some 6mm cable and you will be apples. Make sure you use fuses too


Proud BTrol Owner
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[Hodge]

Actually the individual conductor size has no impact for DC or low frequencies. It only effects the flexibility or ability to withstand movement or vibration.
It is only with high frequencies where 'skin effect' occurs which make the conductors appear electrically smaller and multiple small strands or better than fewer large ones.
It is primarily the overall size or cross-sectional area, but also flexibility, that is important here.

Also not to forget is the contact end , crimped , lugged etc...
With smaller stranded stuff , which is softer and has the ability to flatten under a crimp providing a more intimate connection , more strands in surface contact with the lug / crimp.
This in turn helps reduce V loss.

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[altech]

Never buy cheap Ebay Solar controller as I installed this one a week ago and my car battery was down to 10.4 v. not happy Jane. So look for this Fake " MppT " scam on ebay and don't buy. I'm leaning as I go. cheers Alex . p.s. the cheap PWM controller when I started this project , did charge the battery. just saying :-)

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[altech]

Hi Guys, did some searching for a better MTTP charge controller, found that EPEVER brand have good feed back on them. found this WA company that sells them and they are waterproof too. win win . So I ordered the 5206 BP 20A & Bluetooth module to talk to it. from link below cheers Alex
https://offroadliving.com.au/collections/solar-charger

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[Brissieboy]

A couple of things:
- A lot of controllers sold as MPPT are actually PWM. The difference in efficiency is not huge, but they are definitely more efficient. To get the best efficiency they should to be designed for a particular panel as these vary fairly widely in the maximum power specs (ie max power voltage and max power current) so they are usually just a compromise. And it is not easy to tell the difference.
- Almost all controllers will drain some power from the battery if left connected when there is no input from the solar panels. This varies from a few milliAmps to several hundred milliAmps in the ones I have checked, so it is definitely best to disconnect from the battery when not in use for some time.
- Most controllers require the battery to be connected before the solar panels, and disconnected after the panels.
BTW almost all solar panels on fleabay will never achieve their stated power output regardless of the type of coltroller - basic rule of thumb is 1,000watts per square meter max from the sun multiplied by the panel's efficiency (currently around 17% but some better ones are a little higher) or about 170w per square metre of actual panel, not including frame.

[the evil twin]

100% agree ^^^^


Rule of thumb for a layman to check if a Controller really is a true MPPT...

Does it cost around $100 or upwards of $200 for a "name brand" AND does the max input voltage spec exceed 30 Volts?

If the answer is Yes then it is almost def a true MPPT, if the answer is No then it most likely is not.

Do you "need" an MPPT or will a PWM do the Job?
PWM is equal or in some cases better than MPPT if:
- the panels are of similar voltage to the load IE "12 Volt" panels and 12 volt battery bank... (if you run MPPT it is often cheaper and more logical to run "48 Volt" house panels instead of "12 Volt" panels)
- you have good solar irradiance IE direct sunlight and panel facing the sun (MPPT is better if cloudy, off angle, etc)
- panel temp is 40 ish to 80 ish deg (MPPT is better at very low or very high temps).

When all things are in its favour MPPT can be 25 to 30% better but if the above applies the difference can sometimes be barely noticeable between a $20 PWM and a $200 MPPT.
That means in many cases if you keep the same array and upgrade the controller you may get little change but if you keep the PWM controller and spend the money on increasing the array wattage you would be much better off.

[altech]

Hi Guys, the Big and bloody heavy battery arrived today, hmmm did I mention heavy lol. Did some improvements / upgrades to the battery wiring. Now waiting on the real MPPT charger to arrive. keep you posted regards Alex

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[Yeti's Beast]

Where I work we sell household / commercial solar equipment for off grid , grid tie solar etc.
We only use Morningstar controllers as they work. Yes they cost a lot more than most but when you need a controller to look after 600 volts of solar input, you want the best there is.
My camper is set up with 2x 130 watt 12volt in parallel , Suntech panels and controlled by a Morningstar PWM Prostar 30 amp controller. It charges 2 x 120 ah agm batteries without any problems and been set up that was since 2005
It doesn’t pay to buy cheap sometimes.
Think how much is my car/ caravan worth to you?


Proud BTrol Owner
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[MudRunnerTD]

Hi Guys, the Big and bloody heavy battery arrived today, hmmm did I mention heavy lol. Did some improvements / upgrades to the battery wiring. Now waiting on the real MPPT charger to arrive. keep you posted regards Alex

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Looking heaps better mate. Well done on taking advice. Nice job mate.