You will need a source of electricity to survive long term with any decent level of technology. Electricity allows you to keep light bulbs going constantly, and thus gain the ability to grow plants inside for food, medical, and air production.
Solar cells loose efficiency over time. Some solar cells have been tested after 20 years and found to have lost 11% efficiency. Cheap Chinese imports are said to loose efficiency much faster or simply break down, most likely do to poor quality manufacturing standards.
If a nuclear winter happens you'll have far less sunlight to power them, and a higher chance of them being covered. They can be also be damaged by hailstones and other hazards.
To product against an electromagnetic pulse, a Faraday cage can be built around them out of chicken wire. Covering the front with chicken wire will lessen the amount of sunlight that gets to them of course.
Having enough solar cells to power light bulbs inside your home, will allow you to grow food indoors regardless of the outside temperature, drought or floods, insects, weeds, or other problems. It also hides what you have from raiders.
Windmills and wind turbines are vulnerable to powerful storms. The noise vibrations from the larger ones is so great it causes heart problems from anyone too close to it. Check the information before you decide to set one up nearby. You can make junk metal windmills from a car alternator and some boards.
As long as nothing disrupt the path of the water you are tapping for power, and it doesn't freeze over, and there isn't enough garbage floating in it to clog up or damage your turbines, then tapping flowing water for power works out great.
If you have an abandoned mineshaft far enough down to produce enough heat to produce electricity, then you are in great shape. You can survive just fine no problems at all.
Combustion produced powerEdit
- Wood can be converted into wood gas and used for fuel. See the Wikipedia article at wood gas for more information about that.
- Ethanol can be produced for fuel for vehicles or generators as well, using sugarcane, corn, potatoes, or other sources.
- Methane gas can be made from animal dung, and used to power a generator.
- Animal fat can be turned into biodiesel and used in tractors or diesel generators to make electricity.
Microbial fuel cellEdit
Bacteria can be used to make electricity. Whether anyone has a setup that can power a light bulb constantly, and from that alone make enough light to grow food and air plants by, I have no idea.
Instead of relying on electricity for heating and cooking, you can also burn methane gas produced very easily from water and animal poop.
Some species trees can grow over six feet a year, so if you want to rely on firewood, you can plant these to make certain you never run out.
You can also build solar ovens, or even a Fresnel lens to cook with using the power of the sun.