Wobble Box Solar system

[martinW]

Hello,

I am going to put solar on the wobble box (touring caravan). I am thinking of using a Victron 175watt solar panel and a Victron smart solar controller. The intension being to drop the mains hook up requirement when touring.

So my main question is do I go for more panels? I can fit 2 x 115watt panels on the van, or possibly 2 x 175 watt panels (or 2x 140 watt as all these panels are only 668mm wide).

1 x 175 watt panel cost £150
2 x 115 watt panels cost £200 for 230w
2 x 140 watt panels cost £260 for 280w.
2 x 175 watt panels cost £300 for 350w.

I have yet to measure the DC loads to see how much power we are likely to consume on a daily basis with water pump usage for showers and blown air heater (fan only as on gas). I will probably do get this done in the next few days.

I intend doing the install only once so its now or never for 2x panels, the larger 305 watt panel (£260 and 1000mm wide) will probably not fit. I might also install a 240v inverter for occasional microwave use (maybe once every day for 6-8 minutes so around 100-150watt hours of consumption). Also if I have plenty of power to spare I might use our 600w electric kettle instead of gas....

Would 230 to 350 watts of solar be overkill? Obviously even in July (in the UK) I would only generate around around 1700 watt hours of power with a 350 watt panel system. My gut feeling is go for the 2x panels that I can reasonably fit as you can never have too much solar, but what do you all think?

thanks

Martin W

[Joeboy]

Hello,

I am going to put solar on the wobble box (touring caravan). I am thinking of using a Victron 175watt solar panel and a Victron smart solar controller. The intension being to drop the mains hook up requirement when touring.

So my main question is do I go for more panels? I can fit 2 x 115watt panels on the van, or possibly 2 x 175 watt panels (or 2x 140 watt as all these panels are only 668mm wide).

1 x 175 watt panel cost £150
2 x 115 watt panels cost £200 for 230w
2 x 140 watt panels cost £260 for 280w.
2 x 175 watt panels cost £300 for 350w.

I have yet to measure the DC loads to see how much power we are likely to consume on a daily basis with water pump usage for showers and blown air heater (fan only as on gas). I will probably do get this done in the next few days.

I intend doing the install only once so its now or never for 2x panels, the larger 305 watt panel (£260 and 1000mm wide) will probably not fit. I might also install a 240v inverter for occasional microwave use (maybe once every day for 6-8 minutes so around 100-150watt hours of consumption). Also if I have plenty of power to spare I might use our 600w electric kettle instead of gas....

Would 230 to 350 watts of solar be overkill? Obviously even in July (in the UK) I would only generate around around 1700 watt hours of power with a 350 watt panel system. My gut feeling is go for the 2x panels that I can reasonably fit as you can never have too much solar, but what do you all think?

thanks

Martin W

I run a 100W panel on my van powering the fridge and laptop for movies. It is enough (just) on good days but the 110Ah LB is on a downward trend.from day1 if parked up offgrid. I'd go with more if doing again. As with on homes, you can't have too many panels.

I see a peak of 16.9V coming in from the 100W panel.
The fridge pulls 45W.

This may be of use for a read?
https://www.camperlands.co.uk/camping-i ... batteries/

[Stinsy]

Be careful. 16.9V will be frying your leisure battery!

[Joeboy]

Be careful. 16.9V will be frying your leisure battery!

That's on the incoming side, it then goes through a charge controller to knock it down. I use a couple of cig lighter type 12V sockets with led adapters to keep an eye on power flows. Incoming and LB remaining.

[Stinsy]

Be careful. 16.9V will be frying your leisure battery!

That's on the incoming side, it then goes through a charge controller to knock it down. I use a couple of cig lighter type 12V sockets with led adapters to keep an eye on power flows. Incoming and LB remaining.

Great!

[martinW]

to DC isolate or not to DC isolate.... that is the question?

Hmmm.... Do I bother sticking a Solar PV DC isolator in the caravan before the Victron Smart Solar 100/20 Controller? Its going to be 48V 9 amps (assuming I go for 2x panels). I will be putting a battery disconnect before the controller inside the van, but I am not sure I have room for the Solar DC unless I can find one with a small enclosure.

As I intend connecting the caravan loads to the smart solar controller output I believe that I will NEED a Solar PV DC isolator as the smart controller can still power the loads with the battery disconnected. Maybe I just stick a DC isolator on the Smart controller loads output?

In either way I will have to label up the Battery compartment to ensure anyone working on the 12v system know that they must isolate the Solar system inside the caravan as well as the 12v battery...

Battery Isolator

[martinW]

Oh I have also realised that I will have to limit the charge output of the Solar controller as it seems that you should only bulk charge the 12v leisure battery at around 20% max amps of the total capacity.

Unfortunately due to the leisure battery failing when away on a Sunday 2 years ago I had to buy a 75 Amp Hour one. grrrr

So limited to around 15 amps max charge for now until I need a bigger battery. It's blooming good thing you can do this in the Victron kit.

Thought I'd put that information out there...

I wonder if the Smart 100/20 controller can simultaneously charge the battery at 15 amps (when charge rate reduced in settings) and still supply 5 amps to the loads (if the need it)? I'll have to try this once set up

[AlBargey]

I wonder if the Smart 100/20 controller can simultaneously charge the battery at 15 amps (when charge rate reduced in settings) and still supply 5 amps to the loads (if the need it)? I'll have to try this once set up

Yes, if there is sun and batteries are not asking for more then it will also power the loads up to its limit