Solar system design for single phase & 3 phase loads

Case: The power supply in UAE is either single phase (230V/1Ph/50Hz) or 3 phase (380-415V/1Ph/50Hz). So some appliances work on single phase and some on 3 phase depending on their electrical load. For example, chillers work on 3 phase and lighting on single.

Since there are 2 different phase requirements this can become a very involved design compared to a single set of requirements. There are several options and each would have a different feasibility:

1. Design 2 separate systems - one for each phase requirement.
2. Design a 3 phase system and then "peel off" individual phases for the single phase areas.
3. Design a single phase & grid hybrid - grid supplying the 3 phase
4. Design a 3 phase & grid hybrid - grid supplying the single phase

In addition to these options you must decide what you wish to do about the two major contingency factors: extra electricity, and electrical shortages.

Excess
1. Sell excess back to the grid
2. Store excess for use during shortages
3. Ignore excess - essentially under use the system during its peak generation

Storage
1. What type of storage system would you use?
Battery banks are the most common and generally the most efficient and long term economical choice, but there are a few others.
2. How much storage would you need (i.e. how long would you want the supply to last in terms of amp-hours)?
3. What kind of cycle rates would you expect to have?

Shortages
1. Will you be using only stored excess, stored & grid hybrid, or pure grid?
2. If a hybrid, which will be primary?
3. How long should shortage supply last?

I would suggest you tackle the phase(s) design choice first as they will have dramatic impacts upon the excess/storage/shortage choices. This is where a set of well thought out decision matrix can be of immense help. It will allow you to objective evaluate the choices nest to each other on such things as various costs (set up, operation, termination, etc.), ROI, etc.

Feasibility studies are generally far more complicated than most people wish to admit. What ever assumption you make need to be both carefully documented and researched to confirm validity. Be vary careful when thinking that you can leave out some consideration, generally that is where most people later get stung. The extra time spent up front will quickly pay for itself in a much better fitting design and the ability to make a decision based upon highly improved accuracy of information.