Please Help!! A few Questions on building a System?

The problem is that most AC devices/appliances are designed and operate under the fact that the AC electricity is "unlimited" and steady throughout its operating period. And that the outlet can supply large surges in power.

A simple AC alternator (solar thermal) or inverter (solar PV), just cannot meet these expectations and run near 100% output for 5-8 hours a day... Take a refrigerator--simple AC motor powered system. If the power is cut (cloud passing, another heavy load starts), the motor will stop/stall, and it must site for 5 minutes or so to let the freon pressure inside the heat exchangers drop so the motor can restart. Also, if there is not enough "sun", the voltage (or frequency, or both) will sag and you will have a brownout condition--causing the AC motor to draw too much power and eventually will burn itself out ("in the old days", utilities use to brown out when they had problems--now, they just cut the power until they can restore 100% service to prevent these sorts of problems).

I understand your concerns about storage--This can easily increase your power costs by 2-4 times... But, if you are using standard appliances designed for utility power--your choices will be limited. Either install storage (battery, hydro/pump system, etc.) or make your "generator/collector" much larger than needed to support surge/low light situations.

In the end, you are stuck in the typical engineering rock and a hard place--Either you design your energy source to feed the expectations of loads designed for utility power--Or you look at the entire "sun" to application and possibly redesign both to be more cost efficient/appropriate for the location (example, say your load is a large refrigeration/freezer type application. Design for variable speed DC powered refrigeration pump and use water/salts/wax to allow you to over cool during the day and the "cool" storage of the water/etc. to keep things cool at night and during cloudy weather--or you use DC power for variable speed water pumps to pump and store excess water during the day and use gravity and/or small hand/battery pumps for water the other 20 hours per day).

My humble opinion--you will fall into a trap if you don't look at both the power source and power consumer when trying to design/build your technologically/locality appropriate system.

In the end, for small systems--solar PV electric with batteries is probably going to be your only workable solution to your application. Anything else to going to be to expensive/complex to implement on the small/distributed scales you are asking about... Unless you have some specific local energy source (like stream/lake with significant water flow and drop) available.

Other issues like building a complex central power source (like a 5 kW unit suggested here) and probably distributing the power using copper/aluminum wire is an issue in itself--in many places, having $50,000 piece of equipment (assuming $10 per watt cost to build/install) and distribution network (lots of recyclable metals that can be sold for cash) becomes a security issues in itself.

Sociological issues/changes can also be a big problem too... Central power either attracts more people to a location (food/infrastructure/social friction) or, if in a refugee camp, keeps the people concentrated instead of returning home--with all of those issues.

As another example, from a small book (actually a kid's book I was reading while waiting for my kids)--A child from Ontario Canada ended up raising money for a well in an African village--very inspiring story--in the "middle" the story was very successful. Village had clean water and prospered--healthy. Then a year or so later, the local "rebels" came by, kidnapped the young boys to be sold to other "rebels" and stole/destroyed/scattered everyone else. End of the story--family found the young African child who had initially exchanged letters with the US student after he escaped from the slavers and helped him immigrate to the US (adopted?). The well projects are still ongoing (as I last read)--but the problems can be huge.

So--in the end, your project needs to address an entire range of issues (which you undoubtedly know better than I) for it to be successful.

-Bill

PS: Found the book Ryan and Jimmy and the Well in Africa That Brought Them Together.