Solar question....

[offroadbiker]

Backround

I currently have a C-Tek 250S in the patrol connected to 2Batteries, which offcource charge via the alternator, and then a loose solar pannel that I currently have stashed under the roofrack.

Question:

I aquired a hard shell rooftop tent and was thinking I should maybe add a solar panel to the roof. So what is my options?

1. Can I also connect it to the C-tek seperately (thus 2 pannels but each operating on their own)?

2. Can one somehow connect it to the loose solar pannel so that they run in parralel?

3. Can I connect it via a sepperate MPPT controler to the same 2 batteries?

Input would be highly appreciated.

[pgreeff]

I'm not that familiar with the CTek as I don't do overpriced brand names. But I understand this one is used for charging from your alternator and doesn't have a solar input but you're welcome to correct me if I am wrong.

1. Can I also connect it to the C-tek seperately (thus 2 pannels but each operating on their own)?

Don't know the CTek well enough to answer this.

2. Can one somehow connect it to the loose solar pannel so that they run in parralel?

Thats what I currently do for my camping setup. Although my panel is not mounted to the car, I have a second panel in case I need more power. I can run off one, or I can add the two in parallel to double the charge current. It is easy enough to wire three brad harrison plugs together to form a two in, one out connector.

3. Can I connect it via a sepperate MPPT controler to the same 2 batteries?

Although some would argue against it, the batteries don't know if you're charging from one or two sources so they wont care. They just see current, or more current.


I have a WRND dual battery setup. Normally the WRND keeps the battery topped up from the alternator on the one input, and accepts solar on the second input. It picks the best source of power available at the time and will charge up to 20 A.

[pgreeff]

Just had a quick look at the CTek, "The D250S DUAL automatically selects the best connected DC energy source (of 2) for the purpose and switches between these energy sources to achieve high-efficiency, multi-stage, charging.," so I was mistaken.

In fact, it seems to do exactly what my WRND does, just at three times the price. It looks like decent kit.

I don't see any reason you should not be able to run your second panel in parallel to the first as I do. It will double your current. Only provision is that the panels should be the same. If you have different spec panels this might not be ideal and you would be better off with a second charge controller for the second panel.

[ricster]

I am no guru when it comes to electrickery, but can one not have an isolator switch that will then be set to draw from the panel on the roof, or switch over to the panel under the roof rack if need be. But I think they need to be the same spec panel to function in parallel at the same time. But may be mistaken on that.

[Peter Connan]

Phone Ant. He will be able to tell you what you need.

But I want to ask if it's really worth sticking solar panels permanently to the top of the tent.
The solar will not work while you are driving, as the alternator will be providing more power.
So for them to add anything, you have to park up in the sun all the time.

I r3ally think it's better to have loose panels and a long extention lead...

[Kagiso II]

Panels can of different output but just correctly connected [in serie] I have a 120 W and an 80 W on my Bundutop. I use the ROYAL Regulator, and while the car engine is running, charges to battery [105 Ah Willard Deep Cycle] and 22 months like that now .. No hassles
The battery from alternator charge is controlled by National Luna dinges .. switches out when ignition is off and only sends through 5 minuites after engine gets started.
My fridge is always set to -10 or higher for the summer outreaches

[Anthony Forgey]

You can connect 2 panels.
but...
the total voltage must not exceed 23 volts, so you probably can't connect them in series unless they are very small panels
so, connect them in parallel.

I agree with PC. Don't mount to the vehicle because you invariably camp in the shade. Loose panels can be positioned for best sunlight.

[ricster]

A C-TEK 250S can ONLY handle 20 volts (might be 22 or somewhere around there - don't have the booklet with me at the moment). Series connection on 2 x 18v panels makes it up to a max of 36v.... you will blow the C-TEK good and solid. I have one to, and did something similar many years back and luckily C-TEK replaced the whole unit for me free of charge. Great customer service, even though it was my fault.

[offroadbiker]

Thanks for the input, much appreciated.

For me it is more of a storage issue as there is not place for a second pannel under the roofrack.

The best might be then to have the second panel on the tent, but not have it there as permanent...

So I then would want to take the 2 pannels from the 2 different "storage" places, connect them parralel and then run a long lead to the C-teck?

[NoPressure]

I am no expert, but the 1+1 panel is a relatively easy fix.

Put 2 x BH plugs on top of one another. Wire them in parallel with one another - and with one pos. and neg. wire going to your ctek.
Thus, use one plug permanently with rtt solar panel and then when the portable one is setup - plug it into the open BH plug.

I can try and make a drawing of this mental picture of mine?