Those emergency packs which have:
-Small AGM battery
-possible internal very slow battery charger
-Air compressor
-Lights
-12vDC to 120vAC Inverter
-Jumper cables
Might be convenient, but are convenient for short durations only.
The Air compressors have a short duty cycle before they overheat and become worthless. 15 minutes on 30 minutes off or they quit.
The AGM battery is usually 22 A/h maximum.
The lights are just power sucking incandescent
The inverter is usually a square wave inverter that puts out a lot of electrical noise, and can quickly deplete the internal AGM battery.
If the AGM battery is not promptly recharged after use, or recharged monthly, In a year or 2, it will not have enough juice to jump start a vehicle.
This is the battery which came in my small Jump pack and probably many others.
http://www.batteryplex.com/universal.cfm/m/UB12120-F2?gclid=CIC9wI3o5KECFWEd5wodOj3lIg
This battery cannot start a vehicle with a fully depleted battery, but will work 90% of the time.
It is 25 dollars.
The solar panel might need 6 hours and possibly much more of sunlight before the battery could start the vehicle. If it then does not work, start over.
If the solar panel is charging a house battery, you could jump the vehicle from the house battery.
I have this compressor. It works very well. harbor freight has a knock off.
http://www.amazon.com/Industries-MV50-SuperFlow-Hi-Compressor/dp/B000BM8RT8/ref=sr_1_1/179-4366909-2461118?ie=UTF8&s=automotive&qid=1274499653&sr=8-1
Devices with electric motors such as a 120 volt ac air compressor can overheat when run on a MSW inverter.
If you are interested in this combo of compressor and small battery,I can show you how to easily charge it from your vehicle as you drive, or use it as a jumper battery.