Electric cars

Martyn1981

AnotherJoe wrote: »

With refeence to, on a car, that's fairly obvious I'd have thought. Even best case, some panels are always in the shade, and the whole car may be and no panels will be at optimum angle.

Flat mounted at 85% of optimum is actually better than my E/W arrangement at 80%. But E/W allows twice as much PV to be installed, and at less than twice the cost, and that's the roofing I had to work with - Perfect is the enemy of the good - if (and I accept what you are saying, hence if) the install makes economic sense, then you would do it too, you wouldn't not do it because something else you've done is better.

Take that to the extreme and there would only be one PV farm, and one wind farm in the whole world as all the others would be less economic. The decider is the economics of the individual project, not how it compares to other non-competing projects.

Do many (any) of us get better value from our cars than say a taxi driver would? If not, are our cars valueable, worth having in comparison, or should we just look at their value to us when making a decision yes or no.

AnotherJoe wrote: »

My comment is in respect of, if I had (say)£2k should I spend them on solar on a car, solar on a roof, or just buying electricity. I think that on a car is nearly always the worst option.

I think this is an example of a false dichotomy. Would you really cross-shop across these options, and even then, are they truly mutually exclusive in that you wouldn't opt for a more economical car option, if a different option existed elsewhere. I accept the argument within your statement, but don't believe that the situation is a reasonable one.

Herzlos

AnotherJoe wrote: »

Note, all my comments were / are in respect of panels on cars not trailer roofs.

My comment is in respect of, if I had (say)£2k should I spend them on solar on a car, solar on a roof, or just buying electricity. I think that on a car is nearly always the worst option.

I agree with this - if you've got a smallish vehicle which doesn't often go near it's range limit and spends a lot of time where it can be charged, then it'd make much more economic sense to put the PV panels on the house roof and feed back to grid / battery and use that to charge the car.


I'm not sure it makes much sense to have a small PV on many domestic vehicles beyond keeping the 12V starter or leisure battery topped up. There's unlikely to be enough roof-to-vehicle ratio to justify a panel to boost the range. I also reckon a car will spend more time in shade than a commercial trailer (closer to buildings, in garages, multi-story car parks etc.


It may make sense on things that are designed to run away from the grid, where the range extension would be useful - vans, utility vehicles and so on, but not for any random domestic vehicle.

I wouldn't pay extra to get one fitted.

NBLondon

Herzlos wrote: »

I'm not sure it makes much sense to have a small PV on many domestic vehicles beyond keeping the 12V starter or leisure battery topped up.

If anybody builds an electric motor home (EV RV!) then it would make sense to use that rather than impact on the range of the drive battery. And if the campsites offer charging points by adding an extra cable and adaptor to the existing power ones - great option for the retired cruiser.

AdrianC

NBLondon wrote: »

If anybody builds an electric motor home (EV RV!)

You mean like the one Nissan Spain were waving around this summer, based on the e-NV200?

https://www.youtube.com/watch?v=q1MtYU1ELg4
(The story was that it is/was orderable through dealers, but there's nothing on nissan.es)


Or the ones that various converters have been building on the same base for three years or so?
https://www.hillsideleisure.co.uk/blog/the-dalbury-e-electric-campervan-review/

Herzlos

NBLondon wrote: »

If anybody builds an electric motor home (EV RV!) then it would make sense to use that rather than impact on the range of the drive battery. And if the campsites offer charging points by adding an extra cable and adaptor to the existing power ones - great option for the retired cruiser.

Wouldn't it make more sense to just run the leisure off the drive battery? It'd vastly increase either the power output or the battery duration, and simplifies things a bit. It does mean that potentially if you're running stuff in it for too long without being plugged in you'll hurt the range, but presumably the same happens when you're charging the leisure batteries from the combustion engine.


An EV RV would be great, so would an EV + E-Caravan actually. Slap a ton* of battery under the caravan floor and you've just boosted the range of the tow car dramatically as well as boosted the power usage of the van.


* Doesn't need to be literally 1000kg, but even then you'd be pushing a 1400kg up to 2400kg so you'd need to pull it with something bigger.
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AdrianC

Herzlos wrote: »

Wouldn't it make more sense to just run the leisure off the drive battery? It'd vastly increase either the power output or the battery duration, and simplifies things a bit. It does mean that potentially if you're running stuff in it for too long without being plugged in you'll hurt the range, but presumably the same happens when you're charging the leisure batteries from the combustion engine.

The reason there's a leisure battery in a camper is so that you can still start the camper in the morning after you've been "off-grid" for a night, with lights/music/heater/whatever using electricity.

Then, once you start the camper, the alternator charges the leisure battery.
If you're plugged in at the campsite, a charger charges it from the mains.


So while using the "leisure" appliances from the traction battery could well leave you in the doo-doo, if you're off-grid, it's probably more akin to having an eberspacher heater consuming fuel from the main tank. Except more so - the petrol heater in my VW camper uses about a third of a litre per hour, flat out, and we're back to charge-vs-fuel dwell times.

As for plugging in at campsites - many sites restrict hook-ups to 6A anyway.

Anyway, I rather suspect the biggest issue with a camper conversion of an e-NV200 is payload - many campers run close to GVW anyway, and it's often very easy to overload them. Payload in an e-NV200 panel van is just under 660kg, while the ULW of a VW California is about 500kg more than that of the equivalent panel van.

silverwhistle

NBLondon wrote: »

If anybody builds an electric motor home (EV RV!) then it would make sense to use that rather than impact on the range of the drive battery. And if the campsites offer charging points by adding an extra cable and adaptor to the existing power ones - great option for the retired cruiser.

Many such vehicles have awnings which they unroll from the roof, and with the new materials arriving you could have (say) 6-9 m2 of awning generating power. Not sure what that would provide but a few days in some remote campsite might provide a useful boost.

Herzlos

Presumably you could configure it such that the leisure battery can't drain below x miles or percent of charge, to avoid running it to empty. It just doesn't make sense to physically split the batteries, as the leisure battery could hold a few extra miles of range, or the drive battery could provide a few hours* extra leisure.


*I've honestly no idea how much extra leisure. Standard leisure batteries are essentially 2x 12V car batteries?

AdrianC

Herzlos wrote: »

*I've honestly no idea how much extra leisure. Standard leisure batteries are essentially 2x 12V car batteries?

They should be deep-discharge batteries, like golf buggies and the like. Normal lead-acid really don't like being run low, and deep-discharge don't like producing big currents. But a lot of people use cheaper standard batteries, and just have a much bigger capacity so they don't run 'em too low.

Martyn1981

silverwhistle wrote: »

Many such vehicles have awnings which they unroll from the roof, and with the new materials arriving you could have (say) 6-9 m2 of awning generating power. Not sure what that would provide but a few days in some remote campsite might provide a useful boost.

Assuming around 20% efficiency, then 6M2, south facing and pitched (I assume the awning would be directed towards the sun anyway), then around 6-8kWh per day on a nice day (around 5-7kWh's/kWp). [Edit - our whole household consumption in the sunnier 6 months is about 7.5kWhs per day (about 9kWh's in the winter). M.]

It's hard to find a real problem with that idea, so long as the extra cost is economical.