What's the go with running multiple solar panels?

[Slappy]

I'm pricing up and picking gear for a solar setup to into my D22 but I'm not entirely sure when it comes to solar input. I intend to install a panel on the roof permanently and carry a roll out/fold out for when I could use some extra juice.

I'm looking at some of the Kings gear, primarily their 12v Control box & 25Amp DC-DC Charger that has a solar regulator in it. The control box is designed to mate with this charger so has easy connection for the 1 solar panel - if I was to run a second panel would I just need to get a second solar regulator to support it then wire it in along side? I think the control box has 2 Anderson plugs there ready to use so wouldn't be too hard?

 

[Old.Tony]

Solar panels can be hooked up just like batteries. Connect them in series to increase the voltage, or in parallel to increase the current.

A single 300 watt panel will produce 25 amps, so if you've got a 25A controller, a second panel of similar size is going to overload it. You don't want to run two controllers both trying to manage the one battery because they'll get confused over the voltage they're seeing at the battery terminals. A larger controller is needed if you want more panels.

Look at the needs though. Charging at 25A will, on a winter's day where there's only about 5 hours of usable sunlight, produce 125 amp-hours of power. A fridge (on the same winter's day) will draw about 28 amp-hours of power (let's say 30). The fridge is the largest (and most important, in my mind) power consumer in the car/van, most everything else is minor.

My current caravan (we free camp a bit) has a gas fridge, but in the previous caravan I'd changed the fridge to a compressor-based unit (Waeco CR140). I added an 80W solar panel to the 64W one on the roof and we never ran out of power (lights consumed about 2A, toilet about 2A when flushed, water pump about 2.5A). Add a couple of amps for USB devices (tablets, phones) and just 144W of solar was enough.

 

[OldManBeard]

Just to support what Old.Tony said, we have a 180w panel on our camper trailer to keep the 2 x 100 AH batteries charged. As an example, over a 10 day period on the Murray in the cooler part of summer, when we were in the shade from midday onwards, we had no trouble at all, with the batteries fully charged each day before midday. Power was consumed by the 65 litre fridge, water pump (which of course only runs for short periods at a time), lights in the evenings and charging our phones, tablet, lamps & torches, etc. The only thing we did have to do was get the dust, leaves, etc. off the panel every couple of days or so.

 

[Slappy]

Solar panels can be hooked up just like batteries. Connect them in series to increase the voltage, or in parallel to increase the current.

A single 300 watt panel will produce 25 amps, so if you've got a 25A controller, a second panel of similar size is going to overload it. You don't want to run two controllers both trying to manage the one battery because they'll get confused over the voltage they're seeing at the battery terminals. A larger controller is needed if you want more panels.

Look at the needs though. Charging at 25A will, on a winter's day where there's only about 5 hours of usable sunlight, produce 125 amp-hours of power. A fridge (on the same winter's day) will draw about 28 amp-hours of power (let's say 30). The fridge is the largest (and most important, in my mind) power consumer in the car/van, most everything else is minor.

My current caravan (we free camp a bit) has a gas fridge, but in the previous caravan I'd changed the fridge to a compressor-based unit (Waeco CR140). I added an 80W solar panel to the 64W one on the roof and we never ran out of power (lights consumed about 2A, toilet about 2A when flushed, water pump about 2.5A). Add a couple of amps for USB devices (tablets, phones) and just 144W of solar was enough.

Just to support what Old.Tony said, we have a 180w panel on our camper trailer to keep the 2 x 100 AH batteries charged. As an example, over a 10 day period on the Murray in the cooler part of summer, when we were in the shade from midday onwards, we had no trouble at all, with the batteries fully charged each day before midday. Power was consumed by the 65 litre fridge, water pump (which of course only runs for short periods at a time), lights in the evenings and charging our phones, tablet, lamps & torches, etc. The only thing we did have to do was get the dust, leaves, etc. off the panel every couple of days or so.

Rogey that guys thanks heaps for that. I was looking at a 170AH battery paired to a DC-DC with a 140w panel, mainly for a fridge right now but lights and stuff to come. Reassuring that it should be plenty for now! Thanks!