www.treehugger.com/files/2005/08/solar-powered_t.php
writes about a very cool p roject by Canadian engineer Steve Lapp who modified his 2001 Prius by in stalling solar panels on the roof. It is admitted that the car is still a rough prototype, but so far the fuel economy improvement are of 10%, a respectable figure;
Honda Civic engine for the 2006 model and achieved a 6% increase in fuel economy (the comparison is not quite fair, but I just want to point out that it can take lots of engineering efforts to gain even a few percent s). "Lapps modelling predicts a 10%20% fuel efficiency improvement for the 270 watts of PV (to be bumped up to 360 watts with the additional o f a fourth panel)".
can run on electricity alone, w ith their gasoline engines off, offers the opportunity to provide them w ith more electricity and therefore drive further with the gasoline engin e off. Electricity can be provided from the electrical grid by charging an onboa rd battery, and depending on where that electricity comes from, it will have various emissions associated with it.
Howeve r if it is provided from renewable energy sources, such as photovoltaic panels, then it is "green". This begs the question of why not put the PV panels directly on a hybrid car and generate electricity onboard while the car is parked outside, or even while driving. The general reaction of people to this idea is that there could not be enough energy striking the roof of a car to provide enough electricity to drive any meaningful distance. This is where the incredible efficiency of the hybrid car must be taken i nto account. To drive a hybrid car about 1 km, takes about the same elec tricity as to light a 150 watt bulb for one hour! The point is not to dr ive the car using only solar power, but to effectively use solar power t o improve gasoline fuel efficiency. How much gasoline can this photovoltaic hybrid car save? Well lets look at the energy available from the sun on the roof of the car. For June an d July in Kingston Ontario, about 6 kWh of energy from the sun strikes e ach square meter of horizontal surface. If we install 2 square meters of photovoltaic panels on the car and we collect 10% of the energy from th e sun as electricity (well within present PV efficiency), we can theoret ically go about 8 km each day on just the suns energy. If we drive 24 k m on a sunny day, that is enough to reduce our gasoline consumption by 3 3%.
And a quote from the Green Car Congress article: The 300 VDC output of the solar subsystem is attached to the switched sid e of the original Prius battery, so the PV battery cannot recharge the N iMH while the ignition is off. The PV system can inject a maximum of up to 2 amps continuously into the battery while the ignition is on.
The decision not to charge the hybrid when the car is off was a pragmatic choice, given the financial and time constraints of his project. Among other issues, there would need to be a thorough analysis to determined t he optimal PV-NiMH energy flow/charge relationship.
Read next post :: Comments It can't recharge unless the ignition is on? I can only assume a 1st generation Prius (the car modded in this experiment) is at most this efficient, and probably less so. So, say you're going urban speeds of around 35 km/h, that means the sun w ould power about 4% of your trip. So instead of getting 490L/100km, you 'd get 473L/100km. To pay off just the solar panels, you'd have to drive about 800,000 km at current gas prices. Even if the system could charge batteries and get the maximum amount of e nergy from the panels on a daily basis, according to my calculations, if one drives 15,000 miles/yr (24,140 km/yr) and drives an equal distance each day of the year, this solar modification would be able to power 938 km in a year (given variations in insolation values from month to month ). This results in a 39% reduction in gasoline consumption. Keep in min d this is under optimal conditions (car outside getting a day's full sun light every day). And once again, the payback for the panels alone should take about 800,00 0 km - or about 33 years, if the car and the panels were to actually las t that long. Then you'd still have to pay for the inverter, batteries, e tc, and given average battery lifespans, it would never pay for itself. There's a lot easier wa ys to get 4% efficiency gains - like, say, driving 4% less.
Joseph Willemssen at August 17, 2005 04:39 AM Post a comment But before you do - please note the following: a) Imagine you are raising your hand in a crowded room to ask a question or make a comment. If you want product info, plea se contact the company directly. If you have a link to som ething, please be sure to post it this way!
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