The Autonomous Electric Motorhome

These are some proposals I'm drafting for a friend inspired by LG's new Bifacial Solar panels claiming a 25% gain under optimised conditions (like fresh snow) by harvesting the reflections from the rearside.

If this turns into a build I'll continue the thread but I have a feeling somebody might assess the budget south.

What else is as good as snow? Why a white van roof of course!

Lets get a big yellow one!



You can fit 5 modules on that roof.



What can we do with 5 modules?

I reckon with a little bitta synergy from dual alternators, a wind turbine, anna 6kVA backup GenSet it can power;

• 3 Induction Hobs.
• 1 Halogen Grill/Oven.
• A Microwave.
• A compressor fridge.
• Usual Motorhome loads.
• A toaster.
• An electric 500W kettle.
• A hot fill Washing Machine.
• A 5 HP Winch
• A small workshop.
• A small cabin.
• A site office.

32A Single Phase Inlet.
16A Single Phase Inlet.
32A Single Phase Throughlet.
16A Single Phase Outlet.


1.5kWp PV.
1.75kWp with 15% bi-facial gain over white reflector.
1.87kWp temp comp @ 10°C.
Tristar60 MPPT.

3kVA Low frequency true sine inverter with 60A charger and genset autostart.
300VA TS Inverter (backup if preferred).

7kVA Diesel Genset with Electronic Ignition.

700Ah C20 @ 24v Battery (16.8kWh, 8.4kWh to 50% DOD): 12 x 2V forklift cells / OPzS.


~5.37kWh Day average minimum PV gain (Spring to Autumn).
Peak Solar Gain: 12kWh.

Expected Average Daily Loads:

• 40Ah p/d compressor fridge
• 15Ah p/d inverter
• 40Ah p/d electronics, lights
• 150Ah p/d electric kitchen: induction hobs, halogen grill/oven 3.75kWh
• -100Ah per day gain using gas hobs to allow battery to recuperate.

Total Load: 245Ah p/d

Generation Ability

• 223Ah p/d average min. solar gain.
• 37.5Ah p/d alternator gain; 30 min. drive.
• 125Ah p/d Wind Harvest in average 5 m/s.

Design load: 6kW per day.

Designed with inherent redundancy and minimum parasitic loads.

This also works for micro hydro. Just substitute the wind turnip for a hydro turnip.

Speedwell

That's beautiful. :cool:

How much of the room in the van would the setup require?

A lot of this is information repeated from other schematics but I've included it as a whole in an Electrical Distribution Cabinet format.

Speedwell

Speedwell wrote: »

That's beautiful. :cool:

How much of the room in the van would the setup require?

Ahem..truck!

Guesstimating:
5m x 1.6m of roof for the PV
Wind turbine is on a free standing mast..just tail in.
Battery roughly 350kg
Genset would be aboot 1m x .5m x .5m.
Electrics should fit in [scratches ear with a pencil closing one eye] 1m x 1m x 1m.


She's a rig for a ≥7.5tonner I'm afraid.

System will just as easily support a standard domestic fridge. Less efficient but a fraction of the cost. Just connect mains input to Inverter Output instead, ignore the DC power and connect fridge fans to a spare fuse.

[Edit: I should probably mention all the AC MCBs need to be double pole to comply with European regs. some of use just check the polarity before we plug in though]

crabbypaddy

Are the panel going to be cranked up when stationary, I can't forsee 15% from the reflected light otherwise.



I wonder is there a polyurethane equivalent of the light and space paints.

International brightsides boat paint would give a very shiny white finish until the algae sets in.

I suppose you'd want a paint with bronopol or similar in it to keep the cleaning to a minimum.

Fair point P. I can't say to be sure because I haven't experimented with any. I have to take LG at the word of their datasheet.

I think you'll find on close inspection my gen. figures are quite conservative and my load figures are quite generous. 1kW p/d fridge?

The bifacials tout a max gain of 25% over snow. They are glass on glass so some light gets through proportional to the cracks between the cells.
I know what you are getting at and no I'm not putting bloomin' linear actuators on the roof. :P

The gain in theory counteracts the loss associated with flat mounting a panel with the benefit of day-long-day generation and increased production in overcast skies (kinda crap in Winter though, sun's too low).

The agenda of the rig is to maximise the potential of the limited space but you could roof mount 1.1kW traditional 60 cells modules and ground mount 675W on a PWM controller and save ~€350.

crabbypaddy

crabbypaddy wrote: »

Are the panel going to be cranked up when stationary

The more rigging you put back there the more rear-side shading issues you're creating.

http://parkerrver.blogspot.ie/2011/11/solar-panel-upate.html

Nice design, but 60° is required for our latitude in Winter and the actuator will have to live under the panel not beside it.

crabbypaddy

Sir Liamalot wrote: »

The bifacials tout a max gain of 25% over snow. They are glass on glass so some light gets through proportional to the cracks between the cells.
I know what you are getting at and no I'm not putting bloomin' linear actuators on the roof. :P

Go on you know you want to :-p

Wasn't the 25% 1m over fresh snow and you can be sure they tuned the angles I wouldn't be surprised if they generated the snow too for that extra icing sugar effect.

The closer the panels get to the roof the less diffuse light underneath there'll be shadows from the cells, shadows from the frames and shadows from the clamps / mounting rails. I'm guessing you'd need to be well off the roof to get 15%.

crabbypaddy

crabbypaddy wrote: »

Go on you know you want to

Want to? No! I'd have to eat my words...

Sir Liamalot wrote: »

The agenda of the rig is to maximise the potential of the limited space...

...if I pass up on 30% gain in summer and 800% in Winter (if it's actually sunny).

Okay gimme an aluminium frame with decent cross-members, and two of these yolks or similar.



...presto!

crabbypaddy wrote: »

Wasn't the 25% 1m over fresh snow and you can be sure they tuned the angles I wouldn't be surprised if they generated the snow too for that extra icing sugar effect.

Standard Test Conditions: 25°C :pac:
Their little array comparison animation sez +25% with grass indicated. :rolleyes:
Hard find an honest salesman...

So tilt orientation I think is best to face the opposite side of the fridge vents and I prefer light coming in the sliding door.