Whenever I see a question like this, my first answer is always, “It depends.” What factors determine cost?
- How much power do you need?
- How much sun does your location receive in an average year?
- How much of the installation can you do yourself?
- Are you tying into the grid, or will you be completely self-contained?
The last two factors are the primary ones.
If you can install a system and tie it into your circuit box, the cost will range between $7 and $10 per watt. This will give you everything you need to tie into the grid, all the mounting hardware, wiring, power inverter, and backup storage capability. A 1 kiloWatt system would thus cost around $10,000. The installation is not trivial, and you will need a licensed electrician to do the final wiring and connections. Don’t try to get away without a licensed electrician – the insurance implications alone should discourage that.
If you’re having a system installed, that 1 kW system will be closer to $20,000. But this is by far the safest way to go, because a licensed contractor will know how to make sure that everything meets NEC code specifications and standards. Just having that certification might save big money on insurance, which will add in to the potential savings of a system.
For the do-it-yourselfer, there might be a temptation to go with used parts. The main thing to bear in mind is that silicon solar panels have a useful lifetime, typically 25 to 30 years, after which their output degrades enough to be very noticable. If it means the difference between being able to afford to get a system running and not, I’d recommend going ahead with the used panels and replace them as you accumulate utility bill savings. Make sure that you can get your money back if your used panels prove to be poor generators.
So, the answer is $7 to $15 per watt to get tied into the grid. Cut those numbers roughly in half if you are going to be self-sufficient and completely off the grid.
