We picked up our Sunliner Twist last Saturday, and spent the last 2 days at Henry Angel Reserve near Tumbarumba. Great weather, but got me thinking about battery charging alternatives. The fixed solar panel on the roof seemed to work ok, but, being fixed, doesn't operate at it's peak for most of the day. We don't want to go the generator route, too noisy, even the "silent" ones. So, the questions are, how do I connect a portable solar panel, do I plug it into the regulator inside the motorhome, or use alligator clamps to attach directly to the batteries? Do I need to buy a solar panel with a regulator if it's going to be wired into the existing regulator?
A solar panel mounted flat on the top of a van is not really that much behind a portable one. Before and after the peak sun angles a flat mounting is actually better than one stood up. The disadvantage of portable panels is they are not always out there working as they would be if mounted up top. I would be inclined to put your extra panel/s on top and parallel them with your existing one.
In saying the above, if you are adding portable panels to your rig, just parallel them up with the existing ones. This is the same way you would have connected them if up top. Just extend your wiring to the controller and run it to where you can mount a convenient connector to except the portable ones.
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PeterD Nissan Navara D23 diesel auto, Spaceland pop-top Retired radio and electronics technician. NSW Central Coast.
I think that having portable panels as we'll gives you the best of both worlds. If the van is shaded you use the portable and if not you use the those on the van. To connect, disconnect the regulator on the portable panels and connect the two wires directly to the + and - on the van regulator. I use anderson plugs to connect my portables. It is my understanding that if both panels are connected the regulator will will handle the two differing voltages always charging the battery with the highest. The negative of portable panels is that to get the max you have to move them occasionally and this you would only do if your battery was very low And you were after the max input.
I use portables if I am stopped in one spot for a while.
I find that the portables get more power for the same time IF you are prepared to adjust every couple of hours. I do this as it gives me something to do (get out of the chair LOL) and also a good conversation starter as people walk past. I have done tests with a clamp meter with two identical panels, one laying flat and one chasing the sun and there was a fair bit of an advantage. If you are parked under shade then any charge is worth it just lay them flat if you cant be bothered moving them.
If you are going to connect to the existing regulator then ensure it can handle the extra current. You will have to bypass the regulator on the back o=f the panels and I have used larger cables(as large as you are prepared to get as this is where your loss will be.
You could get a dedicated Anderson plug installed to connect to your existing panel wiring before the regulator.
With portables you can put them in the sun even though your RV has shade at some time during the day.
I like lots of power as I can utilise it to enhance my life so I take as much free power as I can get.
Regards
Brian
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11 Mtr house Boat based at Mannum hoping to travel up the Murray as far as I can get then drift back again
It is my understanding that if both panels are connected the regulator will will handle the two differing voltages always charging the battery with the highest.
good vanning.
wassa
That is not correct.
When connecting solar panels in parallel, they must be the same working voltage, however the maximum current of the panel can be different.
If you connect a 24v panel in parallel with a 12v panel, the 12v panel will actually dissipate power rather than produce it, this power dissipation will be in the form of heat which can destroy the 12v panel. Actual output from the pair would be lower than would have been obtained from one of those panels alone.
If you connect a panel with a Vmp of greater than 18v to a 12v battery via a series (PWM) type controller, then you will lose some capacity from the panel.
For instance:
A 200w 12v panel (Vmp of 18v) connected to a 12v battery via a PWM controller will produce around 11 amps max current to the battery, that's about 140 watts of useful power.
A 200w 24v panel (Vmp of 36v) connected to a 12v battery via a PWM controller will produce around 5.5 amps max current to the battery, that's about 70 watts of useful power.
If using a panel of voltage higher than 18Vmp to charge a 12v battery, you would be better to use an MPPT controller.
It is my understanding that if both panels are connected the regulator will will handle the two differing voltages always charging the battery with the highest.
good vanning.
wassa
That is not correct.
When connecting solar panels in parallel, they must be the same working voltage, however the maximum current of the panel can be different.
If you connect a 24v panel in parallel with a 12v panel, the 12v panel will actually dissipate power rather than produce it, this power dissipation will be in the form of heat which can destroy the 12v panel. Actual output from the pair would be lower than would have been obtained from one of those panels alone.
If you connect a panel with a Vmp of greater than 18v to a 12v battery via a series (PWM) type controller, then you will lose some capacity from the panel.
For instance:
A 200w 12v panel (Vmp of 18v) connected to a 12v battery via a PWM controller will produce around 11 amps max current to the battery, that's about 140 watts of useful power.
A 200w 24v panel (Vmp of 36v) connected to a 12v battery via a PWM controller will produce around 5.5 amps max current to the battery, that's about 70 watts of useful power.
If using a panel of voltage higher than 18Vmp to charge a 12v battery, you would be better to use an MPPT controller.
HI
Ditto
PeterQ
-- Edited by oldtrack123 on Monday 28th of October 2013 12:06:46 PM
