Wind and solar power generating options are falling in price; though you might wonder at what point these options will become viable. Well, in the realm of 'green ideology' that decision-point might be reached soon. i.e. The commercial viability of solar and wind turbine systems might soon be at hand. The question is whether you should participate; or defer that decision. I say that it depends - and here is why....
You can buy a low-capacity system to meet your low-capacity needs, but consider several points:
1. Your system is not necessarily an asset because it might not meet your future needs like it might meet your present needs. i.e. If you in future have an electric car, then your small household system will not be satisfactory to meet the high-demand of your car. You'll be back on the grid. The clumsy or gorky system of old will probably not be compatible with your future system.
In the next 10 years, I fully expect some very compelling developments in the fields of energy economics. One of the biggest developments will be in the realm of battery devices. I expect this innovation to come from carbon nanotubes as a form of heat storage or thermal as opposed to electrochemical battery. I fully expect that we will advance material science to a point where will be storing heat on an atom-scale. The materials are already known; its just a matter of engineering a scalable solution. These solutions will be very cheap as well. Carbon and silicon are widely available.
These are exciting times; though you could be forgiven for thinking otherwise if you listen to the tragic greenies. The sad point is that these 'parasites' are destined to sabotage the real progress that science is capable of. The non-thinkers will get in the way of progress. Under our political system, we are looking at another dark ages despite the developments in science. You might wonder how that is possible. The reason will be apparent in 20 years time.