Electrical Supplementary solar

[Dobbie]

Hi..been a lurker and read loads of great stuff. Thanks!

My dilemma....have ordered new Expanda with solar on roof. Sorts out a problem we've had for years and have been mucking around with portable solar for ages so reasonably conversant with all that.

We also want to be able to use 120w portable panels to supplement installed roof panels (via anderson plug direct to battery and with separate solar mppt controller) to maximise solar gain if camped in shade. Have had conflicting advice as to best way to do this.

Has anyone done this? If so, what was the effect on battery charge? Did battery try to equalise solar input from two separate solar sources. Not parallel but totally separate.

One auto electrician is iffy and another is sure it will work. We like to br self sufficient for as long as possible, given usual water supply restriction and can and have managed to be off grid for up to a month .... but not while totally dependent on roof panels only.

Any thoughts / experiences appreciated.

 

[jandl]

Hi Dobbie, welcome to the forum.
I have a fixed panel on the roof and a fold up portable panel that is connected by an Anderson plug to my controller and they work well together. I do have a Ctek 250S Dual controller which has the three inputs, two solar and one from the tug's alternator. When using the solar only, the two panels charge together. I do not have a separate solar panel reg, there is a bit more info in the My Jayco section under My 16.49.1 Mods Have Started. Hope this helps.

 

[Bmhdg76]

Have heard that two controllers do work against each other so as one is charging the other sees this and does nothing. In saying that have never tried it myself.

If you can add an Anderson to the solar panel feed into the regulator that you can plug your folding panel into would be the way to go. This way they both go through the one controller and no issues. This is what have done when setting mine up. Just waiting to get a panel to put onto the roof.

BJ.

 

[Racer]

I am setting up the same thing with our new expanda, installing an additional 100ah batt too. One thing you must be mindful of is having one panel in the shade and one in the sun. I learnt this by leaning on a panel that was in the shad and the other in the sun. Felt extremely hot.

The panel in the shade will absorb some of the power the panel in the sun is producing. To eliminate this I have purchased a Narva 3 way switch 61080BL.

Panel 1 and Panel 2 into switch ------> switch to regulator. This switch allows you to operate individually or together or isolate.

Two solar controllers will not work together on the same battery regardless of MPPT/PWM. One is charging and the other is thinking the battery is at full charge and will go into float. Ensure you bypass your folding panel regulator.

The standard solar controller is a PWM, I had intentions of replacing it with an MPPT however with my set up (120w+190w) a best case scenario calculation I came up with 0.6amp gain, that is full direct sun on both panels. General rule is 600w plus of solar is a real benefit when using an MPPT controller. Price of a reputable MPPT v the actual need for us to rely on that extra is near impossible so I won't be doing it and sticking with the standard supplied controller.

Also, I am using red Anderson plugs so that at no time someone can accidentally plug the unregulated panel direct to a battery.

Different coloured Anderson plugs are compatible with the same colour only. Like BJ said, you could join in between your controller and junction boxes on the folding panel.

 

[Flanders]

G'day Dobbie, have you thought about an extra battery? I spoke with some solar "experts" when I got my Expanda. They said that because I have 2 x 100amp batteries and 100W solar they would be surprised if there was ever an issue. I have all LED in the van / LED TV, engel plugged in, etc. I've never had an issue, even when parked in shade for a number of days.

 

[Dobbie]

Thanks for comments.

We already have panels, power tech mppt regulator and heavy portable cabling from our previous setup which worked brilliantly. All portable and setup with controller cabling and panel connected via anderson plugs which, in new set up, would allow for option of connecting direct or with controller.

New van comes with roof solar and regulator already installed and we want to avoid making changes to that but there will be times when we may need to get better solar input than from shaded panels on roof.

Also want to avoid installing extra battery because of weight.

So it looks like we see how we go with standard setup as per mr jayco factory and use portable solar to charge extra battery in vehicle if needed. No dual battery as never needed it. That way we can charge toys (iPads etc) without compromising van battery.

Unless there's a simple easy solution!!!! Such as wiring external anderson plug to supplied controller with narva 3 way switch.

Will investigate further.

 

[ShaneT]

How many watts are on you roof? How many amps is the regulator? Does your battery slowly get flatter and flatter over the weeks?
I think jayco put 30amp regs in everthing so if you only have 1 or 2 120w panels on you roof you can just add another 120w straight into the same reg.
If you start to loose power just on cloudy days you may just need another battery to get you through, then your solar will top them back up as soon as the suns back out. But with out knowing what you are running of your battries It all just guess work.

 

[Dobbie]

150 w on roof.

30 amp regulator.

No idea if battery will get flatter as we don't have van as yet but trying to avoid that problem before it happens.....and by using what we already have.

What we will run is guess work at moment but van has LEDs tv hws and usual expanda stuff. We're always very frugal with 12v power but find charging toys (phones, ereaders, iPads etc etc ) is a necessity not a luxury so want to be able to continue off 240 in the style to which we have become accustomed! Just not sure how much we will use pump, hws and so on but will find out when van is delivered.

Will talk to auto electrician about a two or three way switch, mounted next to regulator to allow for switching to either roof panels or external and use the one regulator. This should work, I hope. Extra portable panels will be used very infrequently so a switch would rarely be used ....but we'd have the option.

Will let you know if it works or if we abandon the idea.

O

 

[jandl]

What you want to do is definately possible just depends on the reg being fitted in the van. 30 amps is good, can it accept two inputs, I would think it so but I am no expert on solar panel regs/contollers.
On my portable panel I have bypassed the reg that is on the panel and it connects via an anderson plug(Red) to the van's anderson plug which is wired to the reg(Ctek 250S Dual) in the van. The panel on the roof connects to the same reg in the van. I have left the portable panel reg in place and use that when I want to connect to the car, different coloured anderson plug(Blue) so no confusion with regulated (12V) and unregulated solar(21V).

 

[Bmhdg76]

Don't really think you need to go to the extreme of switches... Just simply tap into the solar feed line with another Anderson, disable your regulator on the folding panel and plug in. Even if one is in shade the voltage lost would be minimal. Most panels these days are fitted with a blocking diode anyway to stop this from happening.

BJ.

 

[ShaneT]

Yep no need for anything. Just run another set of wires from the input of the regulator to any type of plug you want, and plug in up to 120w of extra solar, just make sure your panel voltages are close and do not use the reg that comes with panel kits.
I wouldnt go a anderson plug, would be way over kill as there 150amp at 12volt (your looking at 10amps at best) there are much nicer plugs out there.

 

[Racer]

I was of the belief the Anderson plugs were rated at 50amps.

How long have solar panels terminal boxes been running a diode to block any return current?

 

[mfexpanda]

I was of the belief the Anderson plugs were rated at 50amps.

How long have solar panels terminal boxes been running a diode to block any return current?

Anderson plugs come in different sizes . We use the smaller 50amp ones.
And the diodes have been around for a while now

 

[ShaneT]

yer the small ones are 50amps at 30volts.

 

[Racer]

Bypass diodes have been around for a while however blocking diodes are usually found on much larger systems ie house.

I was under the impression it was relied upon by the regulator/controller to eliminate loss when dark or loss of light ceasing a return.

 

[jandl]

A bypass and blocking diode can be the same item but it is how they are connected that determines the function. A blocking diode will do as it's name suggests, it will block current flow from the battery to the solar panel when there is a loss of light on the panel. A bypass circuit is for when say two solar panels are connected in series and one panel is shaded. This shaded panel basically acts a a large resistor and blocks current flow. The bypass diodes do exactly as there names states, allow the current flow to bypass the shaded panel and the panel in the light still charges the battery.
It does depend on which controller/regulator is used as to it's ability to control the possibility of reverse current flow. I have a good quality controller on my portable panel but as it is made up of two distinct panels it does have diodes in the junction box. I did not pay attention to how they were wired, I put a diode in series with the panel output which in effect is a blocking diode but that was to drop the open circuit voltage to below 22V for the Ctek. Just thought I would throw my two bobs worth in

 

[Racer]

Thanks @jandl

 

[Bmhdg76]

My portable is the same as @jandl's in that they have the blocking diodes so no need for me to worry. The in-laws put two panels onto their Motorhome (they purchased the panels and did it themselves) and they came with the blocking diodes on each panel so seem to be a pretty standard thing.

BJ.