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post #1 of 9 (permalink) Old 07-09-2021, 18:01 Thread Starter
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Max charging rate?

Hi all, I have two 95 amp AGM batteries, looking to eventually have two 100 Lithium, 3 x 175 watt solar panels, and a Victron 2kw inverter charger. Thinking about installing the solar first myself just wondered if the three panels and mppt regulator may be too much for the two 95 amp AGMís. To handle. Also got plenty of room on the roof for the panels but one of which will be shaded by the sat dish when in use, so thinking the best way to connect them series or parallel.
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post #2 of 9 (permalink) Old 08-09-2021, 08:08
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The MPPT controller will do it's job if it's a decent one, just make sure it is set to the correct battery type until you change to lithium.


However I see no point at all in having so much solar, we had two 135ah LBs and a 100w panel with a 300w MPPT controller and could wild camp for days on end with no shortage of power, also do you need a 2kw inverter, that is a lot of power, but it may be you have equipment which needs it, but what you describe is far from a balanced system as the inverter used to capacity will kill the LBs in quite a short time, and they cannot take advantage of the 525w solar setup, the only time they would be useful is in the depths of winter when there is less sun and at a lower angle.

I am no expert on this, I just asked questions and did what felt logical and didn't cost the earth.
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post #3 of 9 (permalink) Old 08-09-2021, 08:13
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Dunno if all this is still relevant but see no reason why not just bigger capacities nowadays, but this is where I got info from on my first install.

And this was my wiring diagram from my self build.

Attached Files
File Type: pdf 999 solar Curtesy of aire & sun basic solar system guide.pdf (110.0 KB, 3 views)
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post #4 of 9 (permalink) Old 08-09-2021, 08:30
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With regard to solar controllers, there are a lot of fake MPPT controllers out there, the one that I used and would still use if and when I do another install is this one

https://www.mppsolar.com/v3/pcm20123012-series/

We used to have a couple of really top notch members (Listerdiesel & Techno 100) on here who knew sparky stuff inside out and they used them, so a no brainer, also the support if needed was given quickly in a manner that didn't confuse.

I bought mine of eBay, but cannot find them now so I have emailed the company to see if they have a UK outlet as I know they were looking to set on up.
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post #5 of 9 (permalink) Old 08-09-2021, 11:32 Thread Starter
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Thank you for your replies, on my post I did state that the eventual set up would be two 100 amp Lithiumís and a 2 kw Victron inverter/charger. The inverter charger will be fitted at the same time as the lithiumís, it will not be run using the existing AGMís. We have a Dometic freezer box and when running at -18 it takes quite a bit of battery amps to run it. We also want the ability to run the hab air-con when on European sites where the emu amps are not enough so use the sharing option on the inverter charger.
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post #6 of 9 (permalink) Old 09-09-2021, 23:34
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You might want to calculate how much power the air con is going to use run via inverter off batteries (you probably already have). It's not going to last very long. Depending what time of year (and what latitude) you intend travelling, my thoughts are the more solar the better (payload permitting).

I'd be thinking if it gets so hot you want air con, find a site with EHU that can run it. However I suppose if it is that hot, it's likely also sunny, so with enough solar and batteries it might work.

For your question - you can't overload batteries with solar. If they produce excess it just doesn't get used. That's one function of the controller. One problem is you have to put the van in sun for the solar which makes it more hot inside, so you need more air con. I have thought an option would be portable panels (as well as the roof mounted) so you could park in the shade if desired, but still get optimal solar.
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post #7 of 9 (permalink) Old 10-09-2021, 10:30 Thread Starter
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We have the hab air-con mounted above the rear bed, for some reason I donít adjust to temperature very well. The idea is to be able to cool the sleeping area prior to gong to bed. The air-con is too loud to run when in bed but if I start off cool and can get to sleep great. As stated we also run a Dometic cool box at -18 for medical reasons so that also takes its toll on the batteries.
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post #8 of 9 (permalink) Old 10-09-2021, 18:37
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As regards wiring solar panels, surely they must ALL be in parallel to supply (nominal) 12v to system ?

If one was in series then the system would be supplied with 24v and I suspect the panels would not cope.

Must be parallel.

We live in S. France and the sun is intense to say the least, EXCEPT if we are on a shaded site when the panels will not be able to give full potential. The more panels working, the better the supply will be and even if part is shaded, the rest can produce. A decent controller as mentioned, will cope with that.

Any typo that I make means the errorists win.

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Last edited by Penquin; 10-09-2021 at 18:40.
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post #9 of 9 (permalink) Old 10-09-2021, 21:40
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The controller can handle parallel or series (as long as itís capacity is matched to panel output). There are pros and cons to each. Not hard to Google and find somewhere that explains so you can choose which way to do it. Hereís the first site I found that (partially) explains.

https://www.renogy.com/blog/should-i...-or-in-series/

Iíd say parallel is the best option. Better shade tolerance, but you do need to size cabling right so as not to lose power over any distance. Good info on these sites.

https://www.12voltplanet.co.uk/solar-power-guide.html

http://www.aandncaravanservices.co.uk/
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