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Re: solar on the car roof

Tue Jul 24, 2012 5:13 pm

Hi, I think the solar on top has great merit, I have priced up the ultra thin panels for the roof and decided for fun to add them to the door sides as well, more for advertising solar than for practicality though.

May also help in a crash as it doubles the door skin, grin.

But seriously, the biggest hassle in recharging at least in NZ, is getting permission to instal charger points on land not owned by yourself, the fees one needs to usually pay, while only a $ 5 per day are at $ 35 per week each station, plus the power and the charger itself, nearly equivalent to the cost of giveing away free petrol ! :)
It only works out if there is a lot of other cars using the points and they pay something towards it and at the moment, I think there are only 30 electric cars in the whole of NZ, and only dealer cars here where I live, no recharging points yet, bar of course asking a firm to lend their 240 Volt supplies, which it the most common home socket here in NZ.

So having a way of independently recharging via solar or a gas or diesel generator in the boot for long trips is pretty good as an idea.

Practical, I think so, expensive, ?, yes definitely and say overall a Toyota Prius would work out more economically.

But for those of us who really really want to own and run completely on solar, then costs seem to matter a wee bit less, still important but not so important as being clean and green . :)

So cost aside for a bit, and with the light weight of the panels not being too much of an issue, the thin film solar is a good idea, the batteries if using these type ... eries.html note NZ $, means the weight of batteries for a 500 amp hour set up is not bad at around 55 Kg.

So for minimal extra weight, one could recharge, based on a say a steady 200 watts on a 380 watt set of panels over a working 8 hour day, another 1.6 Kw which added to the 13.7 volts x 500 amps, would give about 8 Kw allowing for some inefficiencies in total to about half charge the car.

That means on say a trip of 100 km, where the trip to work was 50 km, leaving the battery half flat, the solar and battery capacity combined could mean after work, one could easily get home and have half charge left which would allow for a side trip or reduce anxiety on the way home if 100km was the max normal range.

True, one could also do the same by having say 7 x 100 amp hour batteries and no solar, for a weight of only I think of 70 Kg, which is less than a passenger, and this would, with an inverter, give the required 8 Kw or recharge for the day also.

Almost every person we showed the imiev to while we had it on testing days, all said but what if on our trip we forget something or have to deviate on the trip to work. The people we asked had work ranges of 55 km each way to work, and 40 km each way to work and all felt if it had 120 Km range it would be ideal as a work car. This system would give a 155 km range, without needing a plug point except on return to home.

This extra capacity would allow them to use up the full 16 Kw if needed,and yet after a day's work recharging, not needing parking near a power point, simply a normal carpark, be all ready for the 55 km trip home.

If they never had more than one passenger, they could add even more batteries to be able to recharge a full 16 Kw and only add another 130 odd Kg. less than two passengers weight. Using a 20 Kw pack. This would then give a 200 Km range. :)

Fold down the back seats and one could balance the weight better. Of course if one kitted it right, one could also remove the packs for days where the trips were shorter.

Question is, would we do it, the Imev is great as it is for around town, but our driving needs a longer range, and based on the payback period, if we don't do at least 100 km per day, every day, then at a 240, 000 to 320, 000 km needed to be travelled, it will take about 7 years to repay on fuel savings alone.

Simply put, the imiev at current pricing in NZ simply won't pay for itself in our required shorter 5 years we base most work purchases on, unless we do about 130 Km per day.

That means we need to be able to fast charge or at least recharge anywhere independently while at work.

Yes the battery pack will add to the cost of the car substantially, but also increase the resale value when we sell the car after 5 years, and perhaps get us home when no other way will easily work.

If only they put in 28 Kw from factory, it would be great. I would be happy to lose having a back seat if they say left cargo space on top of the higher floor level.

Almost every person I spoke to said yes this 16 Kw imiev would work with work travel, but they / we would only buy it if it had more range. I think if they added a optional battery pack, to say 28 Kw, and no back seats, it would sell way better.

Range is pretty much everything that stops sales here.

Currently only 4 imievs sold in NZ, been on sale I think for one year. If I was selling them, I would invest in infrastructure to support them for tourist used main routes. In fact, we are negotiating now with Japan, on getting a 20 Kw fast charger for testing and if it goes ok, we will use them on the route from Christchurch to Picton and from Christchurch to Akaroa.

Getting permission for the siting on land owned by others is expensive, so we are looking for council sites where we can and buying a multi use property, for the areas not covered by a council site.

It is a lot of investment and for the number of cars here at present not really viable, but we think the number of cars that will like having a recharge point if not expensive as petrol to refuel.

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Re: solar on the car roof

Tue Jul 24, 2012 6:08 pm

I agree with you, Jenn. The city blocks where I'm working are the size of a football stadium, appropriate because I'm working in the stadium right now. The buildings have no exterior outlets, the only charging station within a reasonable distance (and only reasonable because there is light rail closeby the station and work in a free ride zone) is closed off except for demo use at the college. I couldn't build a carport because you need a permit to put up a lemonade stand :roll: , plus the issue of solar is the only way of charging the battery, whereas in the car, I can charge the pack externally at home while the car is plugged in. If the topic was just off-grid charging away from home and didn't involve solar, you could just leave off the solar panel and have only the batteries, but having the solar on the car is the topic at hand.

IMIEVN27, that situation is what is making me think this solar on the car idea is great. Like I said, a round trip is 80 miles, pushing even the LEAF's battery. The i wouldn't make it without destination charging. I doubt the LEAF would, either. The car sits for 10 hours in the sun, no avoiding it, so taking advantage of it would benefit. If I'm adding 26 miles to my drive home range, I can give up a few miles on the way there. The whole system is about the same weight as a passenger, and a passenger won't add 8 kWh of accessible electricity. Also, it was said that cargo space would be sacrificed. Maybe it would, but adding cargo reduces range as well. I probably would take out the back seats if I bought an i and did this, I rarely drive with more than one passenger, or any passengers for that matter. I would agree, range is the issue to widespread adoption, partly by how people think about it. My local dealer has sold 3 so far, one of which I test drove.
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Re: solar on the car roof

Thu Jul 26, 2012 6:41 am

PV1, seems to me the other alternative you might consider is a small trailer with solar panels (which could be unfolded), regulator, batteries, BMS, and inverter, all nicely self-contained. Stick a trailer hitch on the iMiEV (see jray3's post), and you're all set with your stand-alone power plant.
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Re: solar on the car roof

Thu Jul 26, 2012 10:08 am

That could work, and have room for much more solar. I know that there are hitches available, but any in 2"? We have a bike rack that fits into one, also.
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Re: solar on the car roof

Thu Jul 26, 2012 10:50 am

Yep, the ECOhitch receiver from comes in 2", and the added weight is minimal, as it's the same frame as the 1 1/4" version...

"Free" shipping in the US, dunno what it would cost to send 42 lbs of steel to NZ!!
Last edited by jray3 on Thu Jul 26, 2012 11:15 pm, edited 1 time in total.
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Re: solar on the car roof

Thu Jul 26, 2012 1:28 pm

Have you heard of the Solar Taxi? It is a car with a solar trailer, and all in all, the panels still only provided 1/3 of the power needed for the car.


Also, if you are considering this, here is a must read article:
Sincerely, Neil

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Re: solar on the car roof

Thu Jul 26, 2012 1:43 pm

Riffing on JoeS' suggestion above for a trailer: why not trailer mount a gasoline or diesel generator outputting DC, hack the CHAdeMO port, and run it as a "hybrid"? With a big enough generator, you could run all day long. Range problem solved.

Or you could just buy a Volt.
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Re: solar on the car roof

Thu Jul 26, 2012 2:08 pm

TaosEV wrote:Or you could just buy a Volt.
If I was in his position, with mandatory freeway commute, the extended range he needs and the inability to recharge at his place of employment, that's exactly what I would do - That's the scenario the engineers at GM designed the Volt to meet

Our Mitsu was never aimed at people who needed a 100 mile range, nor those who needed to keep up with freeway traffic which is why it was possible to make it as light, nimble, compact and inexpensive as it is - It's an urban econobox, plan and simple . . . . some of us may drive it in the coutry most of the time, but it was still designed primarily for urban use. Trying to re-engineer it to be something else will be a difficult and less than satisfactory proposition I think, not to mention that in the end, you'll likely have enough $$$ in your jury-rigged Mitsu to have bought something which was designed from the gound up to meet your needs

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Re: solar on the car roof

Thu Jul 26, 2012 9:23 pm

If one didn't need to allow for shadows, or night time, say a desert roadway, at a constant 100 Km / Hr , no aircon or Heater, the ImiEv uses approx 16 Kw per Hour.

Can be Slightly less but based on 16 Kw hour, and a full sun onto the panels producing rated capacity, allowing 1 Kw for charger inefficency, you would need a 17 Kw panel. To put that into perspective, That is Four 120 Watt Panels abreast , about the width of the iMiEV, on a trailer that is 35.5 Metre long.

That is about 7 iMiEV's long. That is going to be difficult to park, but would look cool, and you could drive all day.

Thinking about it slightly differently though, if one had 7 hours to recharge the imiev, the the same trailer could be only 5 metres long or about the same as a Hilux or a bit more than another iMiEV on a towbar.

So, Say you only drove at night before Sunrise, 100 Kms to work, worked in the building but parking the imiev in a non shaded carpark with the trailer charging the iMiEV, come out 8 hours later and all charged up again. Drive home the 100 Kms. Might Then need to recharge on house mains overnight though.

Cost of Trailer, $ 1, 000, Cost of Panels @ 2, 000 Watts, $ 4 , 000. Inverter $ 2, 000 = About $ 7, 000 US for free fuel for 100 Km per Day. For the Night Recharging maybe Solar at Home or another trailer at home feeding a Set of LiFePO batteries at say $ 10, 000 US for the batteries.

I appreciate this all sounds a lot, but each year we spend over $ 5, 000 NZ on fuel for our cars. To put it another way, if we invested in Solar and batteries and inverter, an imiev too, it would cost us about $ 14, 000 plus $ 48, 000 = $ 62, 000 NZ

In the last 7 - 8 years we have spent around $ 64, 000 in fuel alone. or about $ 32, 000 each car in fuel.

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Re: solar on the car roof (now about trailers)

Fri Jul 27, 2012 9:37 am

Since this thread has Swung Way Off Topic, so shall I, now known only by a thinly-veiled moniker in order to obfuscate my MiEV's increasingly warranty-challenged status... 8-)

Experiments in range extension are now underway, the first being the effect of extra mass on a downhill run. An extra 510 lbs of ballast, in the form of dead lead batteries en route to the recycler enabled a 20 mile run with a net elevation decrease of 490 feet on surface streets with many stops and ZERO net change in estimated range remaining (61 miles), though approx 2 kwh of net energy was expended. Handling was still excellent and the car did now wallow under the weight, (though acceleration was decidedly dimished)...

Anyway, IMHO, the preferred form of range extension for highway travel will be an engine-powered pusher trailer! :o
Most parts have been procured for said device, and road testing should commence by September. A pusher trailer in it's simplest form would be an engine with manual tranny locked into highway gear, plus a hand-controlled remote-operated clutch and throttle. Tow the trailer around town silently with the clutch disengaged, and once one's on the highway, turn on the ignition and pop the clutch! The engine could even be run for optimal power/efficiency, leaving minor speed adjustments to be handled via varying regen. This gives several different operating modes; Dead Weight, which would give a net loss on all trips that don't include a net downslope, Highway Pusher; which should allow ICE-esque 'unlimited' range, and further down the road, stationary genset operation for recharging at remote sites... Another small benefit should be that since my preferred pusher's alternator is integral to the engine, supplemental 12V input can be provided to the iMiEV with no hacking required, which would take load off of the dc-dc converter, and thereby stretch out a teensy bit more range...

Stress to the battery, you ask? I expect to be able to 'float' the traction pack at a comfy SOC during long, level highway runs, while adding a couple of bars on long downhills and spending them again on the way uphill, while pulling fewer amps than normal. This should be less stressful than a regular drive, even though the car would be in operation for far longer than a 'design' 30-60 minute trip.

MPG? It will certainly vary, but these pioneers got Volt-ish mpg on their pushers with cars not capable of regen... (note that this guy is now the chief engineer at Tesla Motors!) :ugeek:

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