Renology 175 w solar enough ?

[Spanners70]

After some help. My van has a factory fitted 2nd battery system. My biggest load is the fridge, a vitrifrigo c51aocn. I’m looking to add solar enough to make the van self sufficient, the fridge label is 12v 3.6 amp, with 42 watt power, looking on the renogy site at a flexible 1752 panel, would this be enough to make the van self sufficient for a few days ? Any one with better electric knowledge able to help ?

 

[drinfinity]

The panel would be sufficient I reckon, the issue is the factory fit second battery. It will have a simple split charge which overall will give you less Ah than you expect. Many threads on here on the better options for leisure battery setup. Easy enough to fix, especially as you will have the cables already in place.

 

[Spanners70]

Thanks drinfinity, have to say I’m a bit lost on the install and being a third party conversion before I got it im not really sure. All I know is it’s factory second battery, I have a cbe DS300 box mounted at the back of the van with a DS120S box next to it (seems to be the mains hook up side). As to how I wire in a panel etc the more I real the more baffled I’m becoming. Quite happy installing wires etc, I just carnt get to the bottom of what is needed. I think it’s just panel, controller and wire that to the leisure battery terminal on the ds300

 

[t0mb0]

This may be stating the obvious, but whether that (or any realistic) solar panel is enough to make the van self-sufficient for a few days depends entirely on the the weather/season. During decent summer weather, it's almost certainly enough for that fridge, during typical UK winter weather, it's almost certainly not and for spring/autumn then it's somewhere in-between depending on the weather...

 

[oleg.shumihin]

if we assume the fridge is always working (which I think is'n correct), then it will use 43W*24h=1032W*h energy. you will need 1032W*h/175W=6h full blast sun to deliver that amount of energy. This is assuming the battery has enough capacity to support the fridge overnight and not considering the efficiency of the solar inverter and the battery - that will require maybe 1.2*6=7h direct sun.

The fridge won't run 43W all the time I believe - the thermostat would turn it on to bring the temperature down when it exceeds the set point. This is a matter of what's the setpoint is, what's the ambient temperature and often you open the door. Assuming the duty 0.5 (30mins run per hour) the above calculation would end up in approx 3.5h direct sunshine on your panel (good luck with in in the UK)

 

[Spanners70]

Thanks Oleg. As it is in last years hottest days if I drove the van so fully charged battery and parked up with the fridge at mid point I’d get about 24 hrs before the battery cut out, as you say that would be worst case fridge running maybe 75% of the time. Off a hook up I then had the problem of recharging with the engine running which I want to avoid, it I could get solar to top up the battery and maybe get to 3 days before it died/required a good drive would be fantastic, maybe I should look towards a 200w panel. Just need to figure out wiring it up,
It’s my first venture into camper vans, bought pre converted. My next one I will order from new, I guess a t7 by then, but I will spec 2 x 100 amp battery’s or even more amps, and have a big panel or two fitted at conversion. Just want to be able to park up and not have to worry about flat leisure battery or defrosting fridge and then a long drive or ages idling to recharge it. Thanks again.

 

[t0mb0]

Those fridges work by cycling on and off to maintain temperature so, thankfully, that worst case scenario of running full blast continuously is extremely conservative. Looking at the Waeco specs, for instance, they quote an active running time of 23% to maintain an internal temperature of 5deg in an external temperature of 25deg, which increases to 35% at 32deg, so you can pretty much divide those energy numbers by 4 in many scenarios.

This lines up with my own experience, where I have a similar fridge, albeit a 250w panel (i.e. a bit bigger), and in the summer you can basically leave the fridge on all summer with the van parked on our north-facing drive and not worry about it.

EDIT: Relevant to my driveway comment is the fact that we live in Kent, i.e one of the sunniest parts of the UK on average.

 

[Farnorthsurfer]

Your issue doesn’t sound like the size of the solar panel but rather the leisure battery type and capacity and also how it is getting charged. As in a previous post you may have a simple split relay charging system which isn’t going to help.
My 160w Solar is controlled by a Renogy DC-DC 50 amp unit with built in solar controller to a 100AH Lithium battery TN100 and it does what you want. I get maybe five days off grid and that’s in Scotland.

 

[Baldrick]

As Farnorthsurfer said, a few days in Scotland even during the worst days of weather is what I got with a California Ocean (with two leisure batteries) during the winter. Heater, lights and gadget charging as needed. That was in the pouring rain and ours only has a 120w panel. Amazing really.
The main factors for this are;

Parking up southward
No tree or other cover
Pop top up

Keep an eye on your voltage and don't let it go below 10.6v under this and life shortening damage will occur to the batteries. Things may turn themselves off before then hopefully.
Taking everything out of your own fridge pre chilled straight into the Van's and also loading with ice blocks also help.

 

[1mperialSoldier]

Your issue doesn’t sound like the size of the solar panel but rather the leisure battery type and capacity and also how it is getting charged. As in a previous post you may have a simple split relay charging system which isn’t going to help.
My 160w Solar is controlled by a Renogy DC-DC 50 amp unit with built in solar controller to a 100AH Lithium battery TN100 and it does what you want. I get maybe five days off grid and that’s in Scotland.

5 days in scotland? How much driving did you do to charge the battery? and what appliances did you use to drain? I'm looking to upgrade my leisure set up with lithium and struggling to see if I want 1 or 2 110ah batteries. I'm thinking 200watt solar panel also. Currently have XV35MF Numax Sealed Leisure/Marine Battery 12V 120Ah but think its given up. Think I need someone to talk me out of the 200ah set up.

 

[Farnorthsurfer]

5 days in scotland? How much driving did you do to charge the battery? and what appliances did you use to drain? I'm looking to upgrade my leisure set up with lithium and struggling to see if I want 1 or 2 110ah batteries. I'm thinking 200watt solar panel also. Currently have XV35MF Numax Sealed Leisure/Marine Battery 12V 120Ah but think its given up. Think I need someone to talk me out of the 200ah set up.

Don't really need to drive it at all. In the summer the heater is never on so the battery is running the lights (summer in Scotland, light most of the time) the fridge, I have a 30l chest fridge which is super efficient, all the cold air stays in it when you open it. And the sink pump and random phone charging.
Have never had to worry about the battery level. In the winter we stay away for shorter periods and use the heater but even so its not really an issue.
I leave the fridge on 24/7 with stuff in it on the drive and the van can sit for two weeks and still have plenty of charge.
Very happy with the set up.

 

[Farnorthsurfer]

5 days in scotland? How much driving did you do to charge the battery? and what appliances did you use to drain? I'm looking to upgrade my leisure set up with lithium and struggling to see if I want 1 or 2 110ah batteries. I'm thinking 200watt solar panel also. Currently have XV35MF Numax Sealed Leisure/Marine Battery 12V 120Ah but think its given up. Think I need someone to talk me out of the 200ah set up.

Currently camped in the wild of North Uist, it’s amazing as ever here, surfing and chilling totally off grid. Parked up on Monday and have not started the engine at all. Fridge, lights, charging multiple phones. Heater for maybe an hour in the evening. It’s now late on Wednesday and my leisure battery is still pretty much full. Parked facing east so the 165w solar panel is getting afternoon sun when it’s out. For sure I am going to need to empty the portaloo and get more water way before the fridge stops keeping the beer chilled. Oh and the Renogy DC-DC is also keeping the van battery topped up.
Just confirming what I said before

 

[Spanners70]

Thanks farnorthsurfer. Looks like it’s the way forward, just wether I go fro one big panel or two smaller panels to cover a panel failure, and a renogy charger. I’m assuming it’s a split realy charger as it’s a factory fit second battery, I’m not really sure what’s involved with that or what it should be replaced with ? I’m hop8ng I can fit the panel to the renogy controller then connect that to the leisure battery terminal of my cbe ds300 distribution box and then hey presto ? A bigger battery or type will have to wait for funds I think. Hoping the solar will get me enough charge to get least a couple of days off grid no engine running.

 

[t0mb0]

Currently camped in the wild of North Uist, it’s amazing as ever here, surfing and chilling totally off grid. Parked up on Monday and have not started the engine at all. Fridge, lights, charging multiple phones. Heater for maybe an hour in the evening. It’s now late on Wednesday and my leisure battery is still pretty much full. Parked facing east so the 165w solar panel is getting afternoon sun when it’s out. For sure I am going to need to empty the portaloo and get more water way before the fridge stops keeping the beer chilled. Oh and the Renogy DC-DC is also keeping the van battery topped up.
Just confirming what I said before

This basically mirrors my general experience, although sadly I've never made it to Uist itself - one day! People seem to obsess over their electrical setups but in reality, assuming you do something reasonably sensible, it's a non-issue when it comes to ability to stay off-grid, water and toilets are by far the most binding constraints.

 

[Spanners70]

I’m not obsessed but off grid my fridge (moan load) flattens the leisure battery in under 2 days so not much use hence me looking at a solar panel to extend the duration rather than idling the engine or driving to charge it

 

[t0mb0]

I’m not obsessed but off grid my fridge (moan load) flattens the leisure battery in under 2 days so not much use hence me looking at a solar panel to extend the duration rather than idling the engine or driving to charge it

Sorry, that wasn’t directed at you specifically - more a comment on the huge number of electrical threads on here generally versus threads on water etc. Solar panels definitely a good idea!

 

[Spanners70]

No probs t0mb0. Just need to get my head round 2 panels or one, can I just connect to the ds300 leisure battery terminal and job done. Or do I need to get my head round this relay charging thing and more in depth wiring….

 

[t0mb0]

No probs t0mb0. Just need to get my head round 2 panels or one, can I just connect to the ds300 leisure battery terminal and job done. Or do I need to get my head round this relay charging thing and more in depth wiring….

I wouldn't worry about the two vs one panel thing too much, just get whichever is most easy and cost effective. Assuming you have no battery monitor shunt attached to the leisure battery, just hook the solar MPPT controller straight up to the battery with appropriate fusing. On the split charge relay, you can either replace with a DC-DC charger at the same time as fitting the solar, or just leave it for another time and run with just solar for a while to see how you get on. The relay is a bit annoying in that your leisure battery won't charge past 80% or so from the alternator (and will lose 20% to the starter if the solar has got it to 100%) but it's not going to actually break anything.

Another option is use DC-DC with a solar input to kill two birds with one stone, but pay attention to the max voltage on the solar input - the combined models tend to be a bit limited in that regard.

 

[Spanners70]

T0mb0, many thanks for that reply really clears things up for me. Didn’t know I will only ever get 80%, won’t help my cause. I shall go down the solar panel and mppt controller linked direct to my ds300 box for now. And look at a dc-dc gadget at a later date. Really appreciate that simple worded explanation on the ins and outs of a vw fit.

 

[Spanners70]

Anyone out there with solar and reimo pop top able to describe or pics of how the wire is routed to allow slack for top going up but not trap the cables putting the lid down ? Thanks