Driving your hybrid on sunshine - Solar Powered Hybrids

No Longer a pipe dream!
I wonder how many people have fantasised about driving their vehicle on nothing but solar energy. The Battery Clinic have come up with a solution that may start a revolution in realising this dream.

Up to now solar power have only been used to power the lights and air conditioning of a vehicle. In this configuration called Solar Assist, the sun's energy is directly contributing to the propulsion of the vehicle.

200 watts of solar panels are mounted on the roof of  a 2001 Estima hybrid, which could theoretically collect 2 Kilowatts of power on a good summer's day. In reality this would be not more than 1 Kilowatt on a good sunshine day and much less in winter.

Power gathered from the panels are stored in the 12 volt battery system unless the batteries are fully charged, in which case it will be shunted to the heat sinks. On first look it does not seem that such a small amount of power can make any impact on the fuel economy of the vehicle, but the reality is very different.

Solar Assist

With Solar Assist, solar energy directly powers the electric motors through the Power Jockeys. This extra power also helps to hold up the voltage of the 12 volt battery system maximising the electric drive mode of the hybrid vehicle.

In stop and start situations where the weight of the vehicle have to overcome inertia the fuel economising effect of solar assist is not apparent. Solar energy previously stored in the 12 volt batteries would have some contribution but this would not be much.

When the vehicle is in motion it takes less energy to keep the vehicle in motion and this is where Solar Assist comes into it's own. It was possible to keep the Estima Hybrid at 100 KPH running at 20 Kms/Litre fuel economy. On the slight downhill slope the economy was much better. As a result the first test with the vehicle on combined street and motorway driving was 15.2 Kms/Litre. This is much better than can be achieved by the vehicle without Solar Assist.

Potential and Implications
Free energy from the sun to drive our vehicles is certainly a seductive proposition. It does not seem possible that two hundred watts on a vehicle roof can make any difference to the fuel economy.

Fortunately the reality is that it made it possible to maintain driving speeds of 90 - 100 KPH at 20 Kms/Litre or better in the Estima Hybrid which weighs 1.7 tonnes. Although the fuel economy in city driving is not improved by much it can be made better with higher capacity HV batteries and possibly more Power Jockeys. We can also increase the wattage of solar panels.

I do not see electric vehicles taking over our motor vehicle industry any time soon. I do however believe that hybrids are the way of the future at least for now until we find a better alternative. Increasing the fuel economy of hybrids can make them competitive in fuel economy even against pure electrics. Changing the fuel source to ethanol and bio diesels will make these vehicles totally sustainable in terms of carbon emissions.

Hybrids are durable, economical and fun to drive. The future is with us now. We should embrace it.

Should you buy a full electric vehicle

Price and data listed here are average and used for comparative purposes only

Maker	Model	Price	Battery	Weight	Range	Economy
	Mitsubishi I-Miev	38,000 usd	16 kWh ($8000)	1080 kg	112 kms	30 kW-hrs /160 kms
	Nissan Leaf	40,000 usd	24 kWh ($12,000)	1521 kg	117 kms	34 kW-hrs /160 kms
	Ford Focus	40,000 usd	23 kWh ($12,000)	1674 kg	122 kms	32 kW-hrs /160 kms
	Chevrolet Volt	30,000 usd	16 kWh ($8000)	1715 kg	56 kms	36 kW-hrs /160 kms
	Tesla Roadster	140,000  usd	53 kWh ($28000)	1235 kg	400 kms	36 kW-hrs /160 kms

Purpose : We will assume that you purchase a vehicle to get you from A to B within your budget and circumstance. For a family saloon the choice would be the Nissan Leaf, Ford Focus and the Chevrolet Volt. The Mitsubishi I-MiEV would be for the short range city commuter while the Tesla will be for those with deep pockets.

Price : Full EV's are priced around US$40,000. This price is about twice the price of a standard vehicle. If you deduct the cost of the battery the price would be comparable to that of a standard vehicle.

Range : For the full EV range per charge is around 120 kms. This is a function of the battery size and weight of the vehicle. This makes the EV suitable only for the short commutes. The Chevy Volt also has a gasoline engine making it suitable for use as a standard family car. The Tesla has a range of 400 kms but the price makes it suitable for those who needs a vehicle as a personality statement.

Battery : This is the bane of all electric vehicle. The lithium ion battery is expected to last 7000 cycles and at 100 kms per cycle the standard EV should do 700,000 kms over it's useful life. I am very sceptical that this figure can be achieved. Even half the distance in my reckoning would be a stretch.

When the time comes for battery replacement the cost of replacement will most probably be more than the vehicle is worth. The argument that with economies of scale the cost of batteries will come down. This is a fallacy. Both Lithium and Yttrium the rare earth metal used in it's production are exotic metals.  If demand increases price will increase due to supply constraints. Economies of scale does not apply.

Putting a life span of 8 years or even 10 years for a vehicle is a turn off for vehicle owners. A typical vehicle goes through several class of owners. First are those who purchase the vehicle new and would use it foe 2 to 3 years selling it then for half it's value. Then comes those who would purchase a near new vehicle also keeping it for 3 to 5 years. Finally those who would purchase a cheap used vehicle expecting to spend a little more for maintenance and fuel economy.

The problem here is that with the cost of battery replacement the people in the second group ie those that would purchase a near new vehicle will find that their vehicle has no resale or even trade in value.

People in the third group will not have the money for a new battery. Those in the first and second group can afford a new battery but they would not settle for a 5 to 6 year old vehicle. It is for this reason that EV's will have great difficulty in finding a mass market.

Hybrids : Hybrid vehicles have taken off and will soon displace the standard petrol vehicles. For one the batteries used are Nimh to facilitate the fast charge and discharge and cost only around $2000 to replace. Many early hybrids (Prius NHW10) are still running 16 years later thanks to HV battery reconditioning technology coupled with HV battery augmentation with the Power Jockey allowing weaker HV batteries to work comfortably with the vehicle systems.

Already we see Renault and Mitsubishi giving up on EV's after spending more than $4 billion in development. Are electric cars dead? I believe not. We cannot keep burning fossil fuels as we are basically fowling our own nest.

"How many times must you be socked in the face before you admit that global warming is causing the wild fluctuations in our weather and 1 billion cars is the main cause ?" When we deem that the cost to us in infrastructure destruction and rebuild is too high we will place a premium on burning fossil fuels. It is when we decide to do this that I see a come back of the EV's with better battery technology and clean energy to drive it.

Car makers turn to petrol 
Electric cars will flop despite subsidies

Fuel octane rating and vehicle performance

About a couple of years ago I had an argument with a motor diagnostic specialist about the use of hi octane fuels. I have always used 91 octane in all our hybrids. His opinion was that we will get 5% improvement in fuel economy if we changed to 95 or 98. I have always resisted this change as the Prius is not a particularly high compression engine and therefore I see no added advantage. In any case the extra cost would cancel out any improve performance.

Chris Read has this to add which to me settles the matter.

Nearly all modern cars (certainly Japanese cars) learn various characteristics, a key one of which is octane rating, any car that has learnt a particular grade will probably react very badly when a fuel at the other end of the scale is used.

If I had a pound for every time somebody had told me they only buy a particular brand or grade of fuel 'because the car suddenly performs badly if another type of fuel is used' then I would be a rich man.  They have all been right in the short term and wrong in the long term.  Every scientific test I have ever seen (last one was performed by the Consumer Association in the UK for the Which? magazine, you can't get any more independent than that) concludes that standard unleaded (91 RON in the UK) gives the best value for money and there is no discernible difference between fuel brands (Shell, BP, etc.).

I choose a RON rating that is within the suitable range for the vehicle and stick to it, avoid premium or performance fuels as the extra costs in producing and marketing such fuel make it uneconomic to use (once the car has learnt to use 'basic' fuel).  If you want to change fuels then disconnect the 12v battery for a few minutes just before changing fuels to force the car to re-learn quickly, this will stop the warning lights.


(If you can, watch the long and short term fuel trim on a scanner (most will do OBD2 or E-OBD), for a few minutes after the 12v is re-connected and the car started.  The long and short fuel trims learn at the same pace for a while, then the long term gets heavily weighted by previous data and changes very very slowly.  It's this slow change that makes the car run so badly for a while after fuel is changed and sometimes puts an error light on.  Without a 12v disconnect, after a few days of learning the long term fuel trim adjusts enough to put the error light off and the cars running improves as it matches the fuelling better, happens much quicker with a 12v disconnect.)

Regards,

Chris.