I pay nothing for the fuel on my solar system since the sun's rays are free. Because the electricity goes through a sophisticated inverter before it gets to my appliances, the electricity is higher quality and more consistent than grid supplied electricity. I do not worry about maintenance because my installer warranties the system for 5 years and the panel manufacturer warranties the panels for 20 years. The inverters are the most complex part of the system and will have to be replaced before the panels lose 15% of their output capacity. With federal, state, utility and local incentives a solar PV system is 1 of the most lucrative and safest investments a homeowner of business owner can make (in many cases better than investing in energy efficiency).

In practice it is unlikely that everything else will match STC, with the temperature being a key place where it is unlikely to match. Different types of modules respond differently to changes in temperature of the module (usually significantly higher than air temperature), but in general if the temperature is above 25°C the performance will be reduced. To run an AC load you will need an inverter, which will have inefficiencies. You will also have losses in cabling. You can spend a lot of money to minimize these inefficiencies but there will always be some level of loss.

In the USA, solar makes economic sense, especially in the sunbelt. I live in a state (Utah) with the fourth lowest cost per KWh in the entire USA, and a grid tie system is at grid parity, without any incentives whatsoever. With the incentives, the per KWH cost, over just the warranted life of the system, is just about half of the conventional alternative (Warren Buffet's Rocky Mountain Power) in residential markets, and is also competitive in the highest small business rate schedules.

We will never be energy independent as long as the electric grids continue to supply us electric power. You may disagree with me 100%. There is another issue and that is the energy economy. When we produced electric power using dams there were no charges for fuels. This was the very first form of generating electric power. As time continued people started to move away for coastal cities and river areas. Thus coal was used to make steam from clean clear water. Remember energy can not be destroyed nor created. The problem that Thomas Edison saw back in the 1930's was it takes thousands of years for our earth to produce not create coal, oil and natural gas. Yet it takes us seconds to burn these fuels.

I guess not too many people know a true cost of an off the grid solar system and how it works. Instead for some reason you want to add some kind of fueled generation. It is very simple once you understand how to produce electric power. You know this section on linked in is all about Solar PV Professionals. Now you have me wondering. It is understood that not too many people understand that if you have no sun you have no power. This is not true. You can store electric power to be used during the non-sun light hours. We will never solve our energy problems if we think the same that caused the problem. The problem is two fold. The world's grids are failing. The second problem is you don't need fuel or diesel motors to produce electric power. The only solution is a true off the grid solar PV system for electric power and solar heat collectors for heat and hot water. Why can't anybody understand; that the most powerful source of energy is not fuel. It is the sun's energy. Fuel is just stored energy, just like a battery.

Distributed energy supply (as opposite to the existing grid system) and energy independence are certainly the future not only in rural areas, but rural areas without access to the grid are the starting point for solar PV/wind power generation and battery/hydrogen power storage.

The missing link is cheap and efficient power storage (long term seasonal is more difficult than short term day/night). Novel battery chemistries are under development that meet required life cycles and other performance parameters (10,000 charge cycles at any PSoD, 100% DoD, no maintenance, ambient temperature), but not yet available for the mass market. Safe and cost efficient hydrogen storage is pure SciFi, as currently available round trip efficiency is less than 20% (H2-electrolysis / storage / fuel cell) and safe H2-storage that you can bring into the household does not yet exist.