Plan for the Future

Unlike other renewable energy (wind/hydro) systems, PV is modular. It allows for a gradual build up of your array and eases your initial investment. With this in mind here are some other factors to consider about future expansion of your PV system:

1. Allocate space for PV array expansion (whether on the roof or on the ground). Buy or build your PV mounting structure large enough to allow for the addition of more modules later.
2. Initially size the wire in your PV array circuit large enough for future addition of modules. Allow for only a 2% line loss. (See wire charts). Properly sized wire will make a big difference in what your modules generate in low-light conditions.
3. Unless expansion is several years away, invest in a charge controller that will handle future array current.
4. Invest in a good set of batteries. Oversize them--it doesn't hurt to have batteries larger than your present needs. A large set of batteries stays charged just as easy as a small set and lasts much longer. Mixing old and new batteries can be a problem. Try to choose large capacity cells over small cells. Fewer cells, fewer potential problems.
5. If an inverter is in your plans, go ahead and wire your house thoroughly for AC use while your walls are open (if new construction) and routing wire is easy. AC wiring (#12/2 Romex) is inexpensive (around $35. for a 250' roll) and easy compared to DC wiring.
6. Wire DC circuits (in new construction) to the different areas of your house even if an inverter is going to provide all or most of your "end-use" power. If your inverter needs servicing and you don't have a back-up, the DC circuits can be utilized for DC lights, DC fans, etc.

* All of these suggestions for future planning should not add greatly to the initial investment of your system, and will in the long run save you time and money.

This Ozark residence intially started their system with four modules on a 8 module tracker. The next year four more modules were added. The wire that runs from the modules through the roof to the batteries was sized large enough to efficiently carry the charge current. Energy demand eventually outgrew the 8 module tracker, so four more stationary modules were added to the same circuit. The same #2 gauge wire was still big enough for conducting the additional power.

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