Mobile Solar Power Station

Intro: Mobile Solar Power Station

This instructable details how I added a 280 watt solar panel and battery system to my Chrysler Town and Country minivan.

Whether you want to be prepared for the next disaster (or Zombie Apocalypse), need electricity for a HAM radio shack on wheels, want electricity when camping, or maybe you want to drive to a dark campsite and power your Celestron 14" equatorial telescope all night long (I'm just saying...), you may want to install solar panels to your vehicle as I have done.

This instructable really does nothing new or novel, it is a demonstration of how I created a mobile solar power station for about $700.

STEP 1: Step 1: Installing the Panel to Your Vehicle

I have a Chrysler Town and Country minivan. It isn't the best choice for a mobile solar power system but one must make use of what one has.

I purchased a number of new solar panels from a friend who had purchased a few pallets of them at wholesale prices. These large panels (6.5 feet long and 3.5 feet wide) produce 280 watts at around 45 volts. I measured my van roof and I can fit one of these large panels on it.

I removed my van's roof cargo rack and measured the screw holes. I bought some 2 inch steel angle iron and cut it to length so that it was about one-half inch wider and longer than the panel when a panel is placed inside the 'picture frame'. I welded the pieces together to make the frame along with 'tabs' that extend out and attach to the holes where the cargo carrier had attached. I painted the steel frame with a rust proofing primer and a black finish coat. Once the paint dried I added weather stripping to the inside of the steel picture frame to give the panel a bit of cushion. Bolts were added to hold the solar panel to the frame.

In order to attach the flat frame to the curved roof of the car I created spacers by drilling a hole through the center of rubber stoppers of various lengths. Using long bolts I attached the frame to the van roof using the rubber stoppers which can conform to the curved van roof.

I currently run the cables from the solar panel through the side window and into the rear of the cab. I resist drilling into the van roof at this moment to run the cables but I may consider this modification in the near future.

STEP 2: Step 2: Battery Box Construction

I chose to purchase two new 6 volt 230 Amp-Hour batteries from a local battery store for $230 for both including taxes. These are rather large batteries used to power golf carts and are designed for deep cycle and hard use. I measured the battery height, width and length and searched the local stores for a suitable plastic storage bin large enough to hold the batteries. I found a plastic file box used to hold hanging files for under $15 that was large enough but not too large.

The flooded lead acid batteries I chose can out gas hydrogen when charging. To capture this gas and vent it out of the vehicle I mounted the batteries inside the lid of the file box. I cut a piece of 3/4 inch plywood to fit the shape of the file box lid. The plywood base sits on the floor of the van, the lid of the file box sits on top of the plywood base, and the batteries sit on top of the file box lid. The file box itself flips up-side down and can be attached to the lid with the batteries inside. I created a battery holder with long threaded rods that hold the batteries to the plywood base as you don't want 64 pound batteries tumbling around should you have to break the car hard.

To vent the hydrogen gas out of the car, I added the blue hose to the file box. Using duct tape to add a small fan to the end of the hose to help draw the hydrogen out of the box. Hydrogen is lighter than air so the file box, being upside down, should capture any hydrogen where it can be removed through the hose. I have not yet added a reliable vent to the van but that's a future improvement. Right now I am venting the gas out the side window.

I also added a 3/4 inch plywood panel to the front of the file box using two angle brackets. This plywood panel will hold the charge controller, the inverter and the 12 volt power receptacles.

STEP 3: Step 3: Connecting the Components

I purchased a 30 amp MPPT solar charge controller from ebay with a remote power monitor panel for about $200.

I purchased a 750 watt modified sine wave inverter from Harbor Freight for $40.

A friend gave me a broken power panel with three 12 volt power receptacles. I created a wooden housing for them and attached it to the plywood panel.

I purchased a few other 12 vDC power cables from a local auto parts store for about $30 in all.

I wired the system as shown in the figure.

A Note about wire sizes:

I made the wire as short as practical. Size the wires to handle a little more than your expected currents.

The MC4 wires from the panels to the Charge Controller have as much as 8 amps.

The wires from the charge controller to the 12 volt DC receptacles is at most 20 amps.

The output of the MPPT controller to the batteries can be as much as 30 amps (although 15 amps is more the normal I see).

The wires from the batteries to the 750 watt inverter can be as high as 70 amps or more!

STEP 4: Conclusion

For about $700 I created a mobile solar power station that can generate 280 watts of power in full sunlight, can supply 750 watts of modified sine wave for 115 volt AC appliances, and can store 230 Amp-hours of 12 vDC electricity.

Comments

[pagray]

Check me on this. The panel you're running is the equivalent of an apx. 1120 watt 12 volt panel. That's some substantial power for a minivan You could probably run a good sized mini fridge

[maewert]

The panel I'm using is 'only' 280 watts which is still pretty good for a minivan but much smaller than your number :-). (The wattage stays the same when converting the voltage from 48 volts to 12 volts, it's the amperage that increases by 4) Even at 280 watts it should be able to run a mini fridge. (Of course you'd want to modify the van so the hot air from the fridge could escape out of the vehicle...)

Calculations:

Assuming 4 hours of sunlight/day * 280 watts gives us 409 KWh per year and a mini fridge takes about 265 KWh per year, so my system has a good margin for losses looking only at the solar side.

Next you'd have to calculate whether I have enough battery storage to keep the fridge running during the expected nights and cloudy days. Mostly depends on where you use it so I'll leave that calculation to you if you really need to know.

For me I just wanted enough power to run my Celestron 14 inch scope (and accessories) through the night.

Best Wishes!

[IbraheemM3]

Wow! What a nice idea

[maewert]

Thanks!

[Lunafireheart]

I made a similar one with my hearse I have 75 watts of power running through the back half of it.from my experience i need to find a wayto cool the back down on hot days its stifling otherwise.l get heat sick was thinking about adding a roof top window ac unit but dont know if thats possible yet but otherwise it works good during cooler weather.

[maewert]

1. You have a hearse. Cool. Hope it is empty.

2. What do you currently do with the power you generate? 75 watts could run a fan to cool the back but air conditioners suck too much juice (like 115 v 11 amp with unknown surge)

Best Wishes!

[JewDee]

I also have a Chrysler Town & Country and am considering installing a solar panel on the roof. I was wondering why you didn't install the solar panel directly to the luggage rack?

[maewert]

I didn't know how to attach a straight panel to a rack that bent with the contour of the van. Removing the rack and installing the panel to the rack's attach points seemed the sturdiest. And the thing is sturdy! First time on the highway at 70 mph was a little scary, but it didn't budge, now I drive without even thinking about it.

Best wishes

[solarddy]

Add a phase lock micro-inverter and plug your van into your house!

[maewert]

Yes, a micro grid tie inverter would squirt some electricity back into the grid lowering my electric bill! The panel I'm using is one of 6 I purchased just for that idea. I got to building the solar panel holder array but stopped when I looked into the permits I would need with the city and the electric company to legally connect it. I'll complete this one day ;-)

[solarddy]

Your application is mobile, according to NEC, a corded plug is an acceptable means of disconnect instead of a hard-wired disconnect switch. Mobile applications need to comply with DOT regulations "secure the load" physically so that the units do not fly off the trailer at highway speeds, so a mobile box trailer and a 30A RV outlet might be your best answer to use those other panels, not to mention you could put some batteries in that trailer! As for electrical grid requirements, the Enphase micro-inverters carry a IEEE certification meaning they are allowed to connect directly to the grid in the USA. Although making them go off-grid is tricky, and a bit costly ($2K) but can be done as well.

[Twizzler]

My concern in this setup is that if the battery bank off-gasses hydrogen in an enclosed space, that is then collected and drawn off through a hose by negative pressure going through a pc fan, isn't there a potential for explosion/fire from potential small spark from the electricity powering the fan? Maybe mounting the fan on the box providing positive air pressure driving the potential gas out through the hose would be safer? Correct me if I'm a nervous-nellie...

[solarddy]

Never heard of that happening in a car before, seen tons of batteries in trunks, I doubt if it'll be an issue.

[maewert]

I am a little concerned that this would be an issue as the batteries are inside the cabin where truck and other normal car batteries have plenty of open air to vent off any hydrogen. So far I have hardly discharged them to the point where they produce much and I keep the windows vented a little just to be sure.

Thanks!

[maewert]

That's probably a good improvement!

Thanks

[solarddy]

So cool.

[bhanupratap27]

so how it has provided profit to you?

how it will return your $700?

[maewert]

Its purpose was not to provide monetary profit but to provide electricity for me where there is none so I can live more comfortably or can do things that require electricity.

However, if you know of a primative village of people who might be willing to trade their 'useless' gold or diamonds for, say, ice cream which I can make with electricity, then let me know!

Best Wishes.

[turbiny]

You should go all the way electric on the van, you will save more on gas then you will on the ele. bill
I think!

[maewert]

I think at 280 watts MAX I could maybe power my electric bike. I'd need a lot more power to run a vehicle of this size. I would love it though! Drive 20 minutes into work and have the batteries fully charged while the van sits in the parking lot would be great.