ALL SOLAR ELECTRIC MOTOR HOME

NO EXTERNAL ELECTRIC POWER NEEDED – NO GAS OR DIESEL NEEDED

You can now get a 40 foot motor home (used in great condition) with a 300 HP electric motor and a battery bank and 30 full size solar panels with 9000 watts total peak power to charge the batteries. Below are drawings showing the detailed design. This entire design is my work as a solar expert and a motor expert and an inventor. 

Below is the design for solar panel wings that unfold for sun and fold for travel. Note they also tilt in two directions to most effectively capture the sun’s power. 

Here is an example of the 300 HP electric motor that is planned. These are readily available and are nearly the same HP as a gas engine used in the average RV. 

If you are as concerned as we are about survival when the grid goes down and gasoline and diesel are no longer available, you will want one of these totally autonomous solar powered electric motor homes.

Built without the need for external electric power, it uses solar panels to recharge the large battery bank inside. Yes, it has the ability to be plugged into power if power is there, but can operate without any electricity for as long as you need.

The tradeoff is time to recharge and and the range of travel on each charge. More batteries offer more range but need longer to recharge. To learn how to get your very own autonomous motor home, write to electricmotorhome@invisco.com

I published a paper  on 7/11/2018 titled “Solar Motor Home | Kurt Shafer is Your Solar Power Expert” Here is that paper. 

In 2016 I designed a solar powered motor home that offers:
A 300 HP electric motor so you can pass all the gas stations.
A bank of batteries that can be charged by an AC source or by solar panels
An array of solar panels mounted on the roof.

This invention uses some unique components:
1. Accelerator with electronics needed to send the speed signal to the motor drive.
2. Coupler to connect AC motor output shaft to the motor home drive shaft.
3. Bus bars rated at 500 amps to connect the battery o the motor drive.
4. Motor mounting brackets for the AC motor to use the engine motor mounts.
For more details email solar@invisco.com

Tesla and other electric vehicle sources are showing us how good the latest technology is in battery powered vehicles. As you will see later in this article, Tesla’s  P90 offers over 762 horsepower and a range of nearly 253 miles using a battery that is small enough to hide in their car.

DESIGN GOALS

1. Maximize range – this is determined by the battery pack. 
2. Minimize recharge time 

RANGE
The Tesla P90 has 762 HP and a range of 253 miles. So, in theory, if we just want 300 HP then using the same battery we should get a range of 642 miles, and at 60 MPH that should be over 10 hours! We know that this Tesla battery is small enough to hide in their luxury sedan body so with the amount of volume in a motor home our range is only limited by our pocketbook. A valuable property of electric motors is that it is likely that the electric motor will have so much torque that the use of the motor home transmission might not be needed.

The next challenge is to cope with the power in amps needed to produce 300 horse power. Electric motors draw 750 watts per HP so the number of watts needed is 750 times 300 or 225,000 watts. At 460 volts that will result in a current of almost exactly 490 amps. It is valuable to note that the huge current is only when the motor is asked to run at full power. It is likely that just a fraction of the power will be needed, especially when cruising. It is only at startup acceleration will more power be needed. I suggest that we use 100 HP as the optimum power. In that case, the power will be about 1/3 of 225,000 watts or about 75,000. Now we can calculate the total storage we want in the battery bank.

The Tesla PowerWall storage is a good example. The PowerWall is rated at 14 KWH total energy with a “Real Power” rating of 5KW. The battery is 50 volts and the output is 120 VAC at a maximum of 30 amps. If it supplies 5000 watts  output and if we need 75,000 watts to run the motor we will need 15 of the PowerWalls. Since the PowerWall has 14 KWH capacity then 15 of them will put out 75,000 watts for just under 3 hours. And it is interesting to see that if we want to be able to run the motor at full power of 225,000 watts we will need 45 PowerWalls to do that. At a retail
price of $5000 each, this is not likely the best path to take. As you can see, the battery is the largest cost of all the components in this system. But we don’t need to pay that much if we eliminate the PowerWall packaging and put raw batteries in a larger container.

Current needed
That current must be connected between the battery bank and the speed controlling variable frequency drive (VFD) by heavy copper bus bars. Bus bar tables on line show that if one wants to limit the increase in the temperature of the bar to 30 degrees C (86 F) then a bar of copper that is 3/8 thick and 1 inch wide is recommended.

Motor mounting
When replacing a gas engine with an electric motor it is necessary to replace the mounting hardware and the connection to the transmission shaft and the gas pedal. The frame (or body)  used for 300 HP motors is technically termed a 449T and it is almost exactly 2 feet high and 2 feet long. The gas engine is larger than that and likely has 2 mounting points at the front of the engine and none at the rear because most vehicles depend on the transmission for the rear mount. It will be necessary to add a mounting brace to the front of the transmission and then add a platform for
the motor.

Speed Control 
Control of the speed is accomplished by a 3 phase speed controller. They are known as a VFD or variable frequency drive and they are available from many sources. One source is vfds.com and another is EBay. VFDs take 0-10 VDC input to control the motor speed. If you look for a VFD for battery input you need to specify a DC voltage input.

RECHARGE TIME
There are two ways to charge the battery bank, using solar power or using land based AC power from the grid. The goal of this design is to be independent of the grid so charge time will be very long on solar alone. Here is what we can expect if we have grid power. Tesla offers a glimpse into the recent advances in low recharge time . Tesla gets a full charge in the P90 in just 1 hour and 15 minutes using 440 VAC! That makes a transcontinental motor home realizable. With New York about 2500 miles
from Los Angeles, one could imagine traveling 642 miles at a time, stopping for a meal and a charge, then another 642 miles, etcetera.

SIZE OF SOLAR ARRAY
Now, if we start with a motor home that is about 8 feet wide and 40 feet long and we just use the top for solar panels and if we hinge panels we get the layout seen at the top of this page. The motorized hinges allow us to put at least 3 panels over the same spot on the roof and 2 of the panels can fold up and out so all 3 are facing the sun. That way we get 30 panels and they can be tilted so that all get maximum power by facing the sun all the time. At 300 watts per panel that is 9,000 watts. We need 225,000 watt hours to recharge the batteries from total discharge. That will take about 20 hours. That means we might recharge in just 2-3 days. Put another way, it is likely that we can drive each day and get enough recharge to drive the next day.

ROUGH PRICE ESTIMATE
Now a rough cut at the cost of this solar powered motor home.

1. Used motor home – there are many listed for sale at under $100,000 and some under $50,000.
2. Batteries – if we limit the power to 100 HP and the drive time to 3 hours we can live with 15 PowerWalls at $5000 each or $75,000.
3. Solar panels – At about $300 each times 30 panels this is about $9,000.
4. The AC motor is advertised on EBay for around $4000.
5. VFDs are priced from $8000 up.
6. Other miscellaneous parts might add up to $7000.
In summary, here are the costs
$153,000 for the vehicle and parts
$20,000 for labor for the parts and modifications.

$173,000 Total