Using Solar Panels On Electric Cars – Dumb Idea
From time to time, I get an inquiry on this blog about the possible benefit of putting solar panels on an electric car to recharge the batteries while it is not being driven. Let’s face it, your typical vehicle, electric or not, spends most of its time turned off, sitting in the open. And, I tell my inquirers that the short answer to their question is “No” and in most cases, it just is not worth it.
If they want the long answer, I explain that solar panels, at their present stage of development, are simply are not as efficient as internal combustion engines, and electric cars do use a substantial amount of electrical energy to move themselves about.
Doing The Math
Let me illustrate: the average home-converted electric automobile consumes approximately 300 Wh (watt-hours) in the process of going one mile. A watt-hour is a measure of the electricity used in a specific amount of time, in this case, one hour. This enables one to think of electricity in terms of a discrete unit.
One might think of a watt-hour as like a cupful of electricity. If it takes 300 watt-hours to travel a single mile, then let’s calculate how much a good-sized solar panel could contribute to replenishment of that energy.
Let’s say we installed one of those 4-foot (1.2 meter) behemoths on the roof of our car. A really efficient one on a brilliantly sunlit day could push out close to 150 watts. That translates, over the space of an hour, to 150 Wh (150 watts/hour). Am I making sense so far?
Okay, in order to move your car one mile, you need to provide it with 300 Wh, and for the solar panel to charge your batteries with 300 Wh, it has to be exposed to sunshine for an uninterrupted period of two hours, at least.
Here’s the math: 150 Wh x 2 hours = 300 Wh. Or, using our analogy, 1 hour in sunlight = 150 cups of generated electricity, and 2 hours in sunlight = 300 cups of generated electricity, and your car needs 300 cups for each mile it goes. Thus, if you want to drive your electric car five miles, your single 150-watt-ouptut solar panel would need to sit in the sun for ten hours total (you need a total of 1500 Wh, or 10 x 150 Wh).
You might get the sort of weather you need to do this in Australia or California, but there are plenty of areas where it would be unusual to see ten hours of sunlight in a month. That is why the solar-powered cars you’ve seen on television scurrying around the Australian Outback are all built very light, very low-profile, and literally blanketed in costly solar panels.
Despite the heroic “coverage,” and the intense Aussie sunshine, they are only able to manage about 62 mph (100 km/h) intermittently. Car companies are still interested in the use of solar panels to augment the power supply for their electric models, particularly in their sunnier markets, to offset the drain from AC, stereos, and other accessories.
However, panels are still not efficient enough to recharge an electric car’s 16,000 Wh battery pack – unless, of course, you can afford to let your car sit in the sun for a month between uses!
I sincerely hope that this adequately explicates the limitations of what a typical solar panel can generate for its dimensions, and why shops that convert standard cars to electric are adverse to advising their customers to shell out a lot of money for such a small return.
Might as well foot the $800 bill for household electricity, instead- after all, that expenditure, at today’s price of electricity, will allow you to operate most electric cars for two years, at the very least!
DIY Electric Car Conversion Guide
Are you planning to convert a conventional automobile into a pure electric car in your home garage? If you are, it is best you read up on the science of EV conversion.
Before you begin your conversion project, check out the Convert2EV ebook by Les and Jane Oke. The Okes live a green lifestyle in Canada and one way of keeping their carbon footprint small is by using pure electric car. The Convert2EV manual was written based on their experience of retrofitting old gas guzzler into electric vehicle.
==> Click here to visit Convert2EV now!
Introduction to Home Solar Battery Systems
Many homeowners choose to pair a photovoltaic solar panel and a deep cycle battery as their initial introduction to the technology. Smaller systems with this configuration are excellent sources of remote or limited application alternative energy. The concept easily scales upward to larger solar battery systems in homes that operate off grid (completely disconnected from the local power utility.)
The two primary equipment decisions are the size of the solar panel or panels to be used and the capacity of the battery or battery bank.
Let’s consider an “off the shelf” commercial package as an example of energy potential and uses.
Xantrex markets a portable power pack, the XPower 1500 for $400 – $450. It’s essentially a 12v battery paired to an inverter with two standard AC outlets and one 12v DC socket. (Solar panels produce DC power, which must be converted to AC for use by appliances and devices.)
The battery can store 60 amp hours. Match this power pack with a typical 40-watt solar panel and the total system cost will be about $800. Given the battery’s capacity, the user would gain enough energy to run the following devices:
- 150-watt, 18-cubic foot refrigerator for four hours
- compact fluorescent light bulb (8 watts) for 75 hours
- 30-watt portable cooler for 14 hours
- 200-watt computer for 2 hours
Both solar panels and batteries are wired in series to increase the total voltage and amp hour capacity of the system.
The size of any battery bank is determined by:
- The storage capacity required according to intended use.
- The maximum discharge rate of the batteries.
- The maximum charge rate.
- The minimum temperature at which the batteries will be used.
The most common batteries matched with photovoltaic panels are lead acid units with the “deep cycle” designation. This means they can be drained down to 20% of their full charge over and over again.
Any battery or battery bank paired with a solar system should have a sufficient number of amp hours to provide power during the longest period in which the location will have no sun or when cloudy conditions will prevail.
Generally high energy applications are completed during periods of peak sun or with the use of a back-up generator while battery banks are used for minimal draw tasks at night.
This is why it’s important to know exactly what you hope to accomplish with your solar panels and deep cycle batteries so your system can be sized appropriately.
The configuration of the system is simple:
1) Photovoltaic solar panel connected to a charge controller – The charge controller is designed to keep the batteries charged at full capacity without over-charging and will contain a blocking diode to prevent a reverse current from draining the batteries at night.
The charge controller may also include a meter to help track the degree of power being generated.
2) Charge controller connected to deep cycle battery or batteries
3) Batteries connected to an inverter where DC power is converted to AC
Beginners should be aware that there’s never any perfect math in these configurations. Output ratings for panels and batteries rarely equate to actual power generated.
The combination and “tweaks” are endless. This is why starting with a simple solar panel paired to a deep cycle battery with limited intended applications is an excellent introduction to the basics of residential solar energy. You will gain both a functioning alternative energy system and a foundation to attempt more complicated and powerful installations in the future.
Energy Conservation Tips – Easy to implement techniques to reduce your power consumption and lower your electric bill.
Convert Your Own Electric Car
Want to know how to convert a conventional automobile into a plug in electric car? If you do, download the 20 DIY Electric Car Conversion Videos e-book.
The e-book will show you videos of homemade electric cars and the different components needed for the conversion project. Click on the link below to download the free e-book now!
==> Click here to download free e-book!
Charging An Electric Car Batteries With Solar Cells
Is it possible to charge the batteries of a Do It Yourself (DIY) electric car with solar cells?
As it turns out, you can.
However, you can’t mouth the solar cells on the car because there is simply not enough surface area. Well, unless you want to cover the entire car with Photovoltaic (PV) cells, that will be cool though, but still not enough.
The only way to utilize solar power on an EV is through a stationary solar array…preferably at your home.
If you are planning to charge to batteries with solar energy, look at your battery charger first.
How much current does it need?
A typical solar panel with 36 pieces of 3” x 6” solar cells is capable of generating 18 volts at approximately 75 watts of electricity. Is it compatible with the battery charger?
The solar array can easily be scaled up meaning you can add more solar panel to increase the current output from the solar cells.
There is a clear benefit of using solar energy to power a pure electric car…you have literally zero cost for driving the EV.
When you are using an EV, you’ve already saved a ton of money on gasoline. Your vehicle running cost is the electricity needed to charge the deep cycle batteries. And when you are using free energy from the sun, your electric car is literally off the power grid. A pure green vehicle!
Would it be difficult to build a DIY solar power system at home?
If a person can convert a gas guzzler to run on purely electricity, building a residential solar energy system is a piece of cake. The system is much simpler compared to an electric car conversion project. You have less components to worry about also.
How much does a home solar power system cost? I did some reading on this subject. The actual cost of the entire system is not very expensive.
A DIY solar panel can be built with a budget of less than $200. You can save a lot of money by sourcing for cheap or recycled solar cells. All you need to know is where to find them.
Convert Your Own Electric Car
Want to know how to convert a conventional automobile into a plug in electric car? If you do, download the 20 DIY Electric Car Conversion Videos e-book.
The e-book will show you videos of homemade electric cars and the different components needed for the conversion project. Click on the link below to download the free e-book now!
