Solar and 12V system plan

[Rids]

So I'm planning my solar & 12V system & having read through a couple of other threads I would appreciate comments & suggestions on my plan...

I've done a demand calculation and it comes to 56Ah (672Wh) per day, this is dominated by the inverter/mini kettle giving a couple of brews first thing, followed by the fridge keeping those beers cool.
I plan to camp in the van for at 3 seasons, so early spring to late autumn; well once it's fully insulated & has acquired a diesel heater too.

Solar Panels;
I reckon on needing at least 250W to match that that demand once the days get shorter & then maybe I'll have to do with only one cuppa in bed before firing up a gas stove for the second in winter.
I like the idea of two panels in parallel as that will cope much better with being shaded than a single would, provided the shade in on one. so for that reason I plan to use longer/ narrower panels lengthways side by side on the roof, probably toward the front. I don't have any plans for a pop top so these will be onto the tin roof.

Really like the Photonics Universe with the round rear cable outlet and single 2 core cable, such a tidy look on the roof and better to wire up.
I am aiming for some stealthiness for free camping so minimal evidence on the roof is a plus.
This would be two 2x160W coming out at £620 or £1.94/W... ouch, but the reports from others do sound great!
438-160W-Black-Reinforced-semi-flexible-solar-panel-with-round-rear-junction-box-and-3m-cable-with-durable-ETFE-coating.html

Also like the Lensun LS-150FX2 again 2x 150W coming out at £380... only £1.24/W.
Black-flexible-solar-panel


Charge Controller;
I need to get rid of the VW split charge relay anyway so a DC to DC with solar input makes sense to me.
Also one which will trickle charge the starter battery also cuts down on extra bits & wires.
I have two single seats and the drivers will have a Sub in it someday so space will be at a premium.

I like the Renogy DCC50S, it has the voltage input headroom and power capacity in hand for those panel options.
dcc50s-12v-50a-dc-dc-on-board-battery-charger-with-mppt-new-version

I plan to look at the Ctek as well.

Battery;
Ordered the van with a 2nd battery so it currently has a Varta 75Ah AGM under the passengers seat.
I plan the "wear" this out (see below) before upgrading to a LipO of more like 150Ah.
I've had a quick look for slim units (2 x75Ah in parallel) which will fit just inside the front section of my Ovano XL bed/drawer which has a bit of a battery/electrics sized dead space.

Inverter;
I'll need at least 650W pure sine, for that mini kettle.
I've been through the energy & high discharge calcs for that and reckon I can get maybe 20mins from a fully charged battery (the one above) down to 11V; phew the mini kettle boils 500ml for a decent mug of tea in under 5mins...
I'm thinking of sticking with Renology as I can give it ac when on EHU and it'll switch over to that, only reverting when someone trims the EHU...
1000w-12v-to-230v-pure-sine-wave-inverter-with-ups-function

I would appreciate some steers on what to look out for on these...

EHU system;
I'll do this someday, so advice on ac to dc changing would be helpful...
I again had a quick look & did quite like the Victon blue smart fully sealed version so I can stick it under the van somewhere...

Thanks for reading this far and in advance for your thoughts....
Ian

 

[Dellmassive]

got a few pics for us @Rids

 

[Rids]

I'm still at the planning stage; so not much to see yet...
I will add some pics of what I have now when I get the van back later today... (and I can join team air. )

 

[t0mb0]

Looks like you've done your research.

I'm still a bit concerned about boiling a kettle from a 75Ah AGM though! How did you do the high discharge calculation for that battery? I can't find find any specs for that kind of discharge rate and obviously the C20 Ah rating is pretty meaningless at that discharge rate.

 

[Dellmassive]

I think a low wattage mini kettle was mentioned....

And Lithium battery upgrade may be in the future....

I think it was also mentioned that the engine might need to be run for a min or two while the kettle was running..... to use the dc-dc to offset the load drawn from the battery.

 

[Rids]

Looks like you've done your research.

I'm still a bit concerned about boiling a kettle from a 75Ah AGM though! How did you do the high discharge calculation for that battery? I can't find find any specs for that kind of discharge rate and obviously the C20 Ah rating is pretty meaningless at that discharge rate.

I calculated then checked the time taken to boil a full kettle & was pleased to be within a few seconds.
Then assumed an inverter efficiency of 90% and a voltage sag to 11V to give a current draw of 61A.
So yeah this is a high rate of 10.81CA for that 75Ah battery.
Then I found a generic discharge chart for lead acid on the inter web...

how-bad-is-it-to-undervoltage-a-12-volt-lead-acid-battery

A bit of interpolation and re-graphing (I seem to like excel) and I got my time estimate 23 mins down to 11V

 

[Rids]

I think a low wattage mini kettle was mentioned....

And Lithium battery upgrade may be in the future....

I think it was also mentioned that the engine might need to be run for a min or two while the kettle was running..... to use the dc-dc to offset the load drawn from the battery.

Indeed all these were discussed at Siibertoft & may be reviewed there again shortly...

 

[t0mb0]

I think a low wattage mini kettle was mentioned....

True, but I was just going off the 650W number rather than any description of the kettle, which is pulling around 55A for an estimated 5 minutes. I'd say that's a fairly brutal load for a 75Ah AGM battery, which is why I asked about the high discharge calcs given I can't find the required specs anywhere online - you'd need a C1 rate or similar to get close.

And Lithium battery upgrade may be in the future....

Yes, I think this could be fairly near term future if the estimate of daily 56Ah draw from a 75Ah battery is accurate!

I think it was also mentioned that the engine might need to be run for a min or two while the kettle was running..... to use the dc-dc to offset the load drawn from the battery.

I didn't see the mention of running the engine with the kettle in the OP? I don't see any reason why it wouldn't work in theory though, if your wiring was up to it.

As a semi-related comment though, gas is really efficient at boiling water!

 

[Rids]

That should read 0.81CA not 10.81 CA; now that would wear it out quickly!

 

[Rids]

True, but I was just going off the 650W number rather than any description of the kettle, which is pulling around 55A for an estimated 5 minutes. I'd say that's a fairly brutal load for a 75Ah AGM battery, which is why I asked about the high discharge calcs given I can't find the required specs anywhere online - you'd need a C1 rate or similar to get close.

Yes, I think this could be fairly near term future if the estimate of daily 56Ah draw from a 75Ah battery is accurate!

I didn't see the mention of running the engine with the kettle in the OP? I don't see any reason why it wouldn't work in theory though, if your wiring was up to it.

As a semi-related comment though, gas is really efficient at boiling water!

Yeah gas really is good at boiling, it really is; but this a work van that I can camp in, not a camper van, so gas boiling requires getting out of bed... which is much easier after that first mug of tea..

 

[t0mb0]

I calculated then checked the time taken to boil a full kettle & was pleased to be within a few seconds.
Then assumed an inverter efficiency of 90% and a voltage sag to 11V to give a current draw of 61A.
So yeah this is a high rate of 10.81CA for that 75Ah battery.
Then I found a generic discharge chart for lead acid on the inter web...

how-bad-is-it-to-undervoltage-a-12-volt-lead-acid-battery

A bit of interpolation and re-graphing (I seem to like excel) and I got my time estimate 23 mins down to 11V

Ah, good find on those charts, makes sense to me. That might be marginally pessimistic too if that's for a standard SLA battery, an AGM might hold up slightly better? Not the kind of thing you really want to test in practice though, unless you've got a battery you've really taken against...

 

[t0mb0]

Yeah gas really is good at boiling, it really is; but this a work van that I can camp in, not a camper van, so gas boiling requires getting out of bed... which is much easier after that first mug of tea..

I admire your dedication to staying in bed...

 

[Rids]

I admire your dedication to staying in bed...

Oh that just comes with age & practice and a bit of rain can help...

 

[russ_e]

Probably cheaper to order a tea via JustEat every morning

 

[Rids]

Probably cheaper to order a tea via JustEat every morning

Worth a try but at 06:00 in the middle of nowhere.... might not get many delivery cyclists to take it on


Anyway enough of my need for early morning Tea...

What do folk think of the PV size and options, the DC to DC etc etc?

 

[Howzat]

Sounds like we have something in common here. Work van come occasional sleeper with kettle 'n fridge here too.
Currently using a sterling DC 30amp charger and sterling 80ah lithium which I think allows at least a 100a draw. Fridge uses about 10% per day and is recharged every morning in about 30 minutes while driving for work. It was using a lot more (more like 20%) when the weather was 28C.
People laugh when they see a fridge in my van but I wouldn't be without it now during the summer!
I have a 800w Duracell inverter (not pure, kettle and ipad charger work fine) and a 600w 500ml swan kettle. That uses up to 8% per boil. The lithium can safely go down to 10% charge so I can easily manage 6 brews and the fridge per day taking the battery down to about 40% leaving some left over for iPad and phone charging and some lighting.
Recharging takes about 3 hours if the battery goes down to 10% using the DC.
Not got solar yet as I'm only doing the odd overnighter but for longer periods away it's gonna be required to avoid running the engine everyday to recharge via the DC. I think 300w would be my minimum too so I can average out 150w with 6 hours strong sunlight which would nearly top up the 80ah battery without loads. More solar wattage (or sun!) would be ideal but gotta weigh up the costs and the practicality of a British summer v's my actual nights away. At 300w and the odd trip out in the van I'd hope that the current battery could sustain me for 3-4 days easily going wild during April to September.
Finally I plan to get a separate solar controller so I've got some redundancy if either the controller or DC fails.
That's my take on it so will be interested to see how you go on.

 

[Rids]

Sounds like we have something in common here. Work van come occasional sleeper with kettle 'n fridge here too.
Currently using a sterling DC 30amp charger and sterling 80ah lithium which I think allows at least a 100a draw. Fridge uses about 10% per day and is recharged every morning in about 30 minutes while driving for work. It was using a lot more (more like 20%) when the weather was 28C.
People laugh when they see a fridge in my van but I wouldn't be without it now during the summer!
I have a 800w Duracell inverter (not pure, kettle and ipad charger work fine) and a 600w 500ml swan kettle. That uses up to 8% per boil. The lithium can safely go down to 10% charge so I can easily manage 6 brews and the fridge per day taking the battery down to about 40% leaving some left over for iPad and phone charging and some lighting.
Recharging takes about 3 hours if the battery goes down to 10% using the DC.
Not got solar yet as I'm only doing the odd overnighter but for longer periods away it's gonna be required to avoid running the engine everyday to recharge via the DC. I think 300w would be my minimum too so I can average out 150w with 6 hours strong sunlight which would nearly top up the 80ah battery without loads. More solar wattage (or sun!) would be ideal but gotta weigh up the costs and the practicality of a British summer v's my actual nights away. At 300w and the odd trip out in the van I'd hope that the current battery could sustain me for 3-4 days easily going wild during April to September.
Finally I plan to get a separate solar controller so I've got some redundancy if either the controller or DC fails.
That's my take on it so will be interested to see how you go on.

Hi thanks for that & nice to hear from someone else who needs a cuppa. I’ll have proper read through tomorrow..
Cheers

 

[Rids]

Sounds like we have something in common here. Work van come occasional sleeper with kettle 'n fridge here too.
Currently using a sterling DC 30amp charger and sterling 80ah lithium which I think allows at least a 100a draw. Fridge uses about 10% per day and is recharged every morning in about 30 minutes while driving for work. It was using a lot more (more like 20%) when the weather was 28C.
People laugh when they see a fridge in my van but I wouldn't be without it now during the summer!
I have a 800w Duracell inverter (not pure, kettle and ipad charger work fine) and a 600w 500ml swan kettle. That uses up to 8% per boil. The lithium can safely go down to 10% charge so I can easily manage 6 brews and the fridge per day taking the battery down to about 40% leaving some left over for iPad and phone charging and some lighting.
Recharging takes about 3 hours if the battery goes down to 10% using the DC.
Not got solar yet as I'm only doing the odd overnighter but for longer periods away it's gonna be required to avoid running the engine everyday to recharge via the DC. I think 300w would be my minimum too so I can average out 150w with 6 hours strong sunlight which would nearly top up the 80ah battery without loads. More solar wattage (or sun!) would be ideal but gotta weigh up the costs and the practicality of a British summer v's my actual nights away. At 300w and the odd trip out in the van I'd hope that the current battery could sustain me for 3-4 days easily going wild during April to September.
Finally I plan to get a separate solar controller so I've got some redundancy if either the controller or DC fails.
That's my take on it so will be interested to see how you go on.

Hi
So, I finally got round to reading this properly... are you running the fridge from the inverter too, or is it a 12V?
Mine is a Dometic cool box style and uses only 0.5ah/h, so about 12Ah per day, I can see that kicking up in warm weather to maybe twice that.

So finally getting up a ladder to the van roof with a tape measure in hand is quite sobering, the ridges on the roof don't help...
I reckon to get two panels side by side lengthways they'll have to be between 400 to 490mm wide to sit onto the outer 3 ridges.

Narrowest I've found so far are 505mm wide & might work with the edge carefully filleted with adhesive... lots of masking needed here tape!
Photonics Universe (PU) do a 130W in this width with the circular rear junction box, which will keep the roof lines clean & drop nicely through the middle of the three ridges.
A pair of these gives 260W and comes out at £1.86/w

Going to a single panel is the next option.
PU do a 180W which is 665mm wide; this will site nicely on the middle 4 ridges, though the rear cable junction box will sit in the central trough, so will need some care to ensure a seal; I'm imagining a PU closed cell foam gasket around it, which I'd back fill with sealant from the inside; I'd appreciate comments.
Cutting this out of cardboard and laying it on the roof is pretty sobering too.
180W at £1.83/w

I'm currently leaning toward the twin panels; gets 44% more power and better shading resilience.

 

[Rids]

got a few pics for us @Rids

Couple of pics of the "dead" space in the Ovano where I'm thinking of putting an electrics panel, and maybe some slim LiPo batteries..

Its 145mm wide, 1160 Long and 310H
looking down into it...

looking in from behind the Kombi seat..

 

[Howzat]

My fridge is 12v.
Looks like you can get slimline batteries for that space but they seem more common in the US and Oz than over here.