Courtesy of DOE/NREL

Cutting Costs?

If you’re considering PV solar energy as an alternative to your existing electrical power, cost is probably your deciding factor. Solar panels/modules make up approximately 50-60% of the installed cost of a solar electric system and fortunately, prices are steadily declining. As an approximation, you can expect to pay a retail price¹ anywhere from $2.00-$4.50 per peak watt for a single solar module, with discounts available on volume. This weeks average retail price² for all brands was about $2.70 per watt. At that price, the retail cost for a 200 watt module would average about $540 (200 watt x $2.70/watt). Considering that a 2000-5000 watt (2-5 kw) solar electric system would require a minimum of 10-25 modules, it’s understandable that there has been a deluge of DIY solar panel guides/manuals coming out of the woodwork.

What I’m talking about are those DIY guides³ that claim to help you build your own solar panel for less than $200 by following their easy to use step-by-step instructions. The idea of saving $340 per module ($540-$200) by building your own solar panel does arouse interest, but is this the right place to cut costs.

Unless your an extremely dedicated DIY’er with plenty of time and energy, I wouldn’t recommend entertaining the idea of cutting costs by building your own panels⁴. It’s not realistic to think you can manufacture quality and reliable PV panel’s in the garage to power your home. A DIY “Build Your Own Solar Panel” guide could be helpful to the hobbyist or someone engaged in an educational project, where you could get enough power from it to run a fan or charge a battery, but don’t expect to build quality solar panels that you can use to power your home.

Most solar panels now have a 2-6 year limited warranty for material defects and a 20-25 year limited warranty for power output that is less than 80% of the modules minimum specified output. Since the average solar panel’s life expectancy⁵ now exceeds 30 years, does it make cents to build your own.



1. Solarbuzz’s “Solar Module Price Highlights: March 2010″

2.120W+ Weekly Retailer Price at PVinsights.com

3. diysolar.com

4. solarpaneltalk.com

5. Solar Panel – Expected Lifetime

Courtesy of DOE/NREL

Part 6 – Cost Comparison – Fossil Fuel Generated Electricity VS Solar (PV) Generated Electricity

In the last segment, I calculated an approximate cost for a solar electric system sized to provide the same amount of electricity I now use in my home. In this segment (Part 6), and the last of this series, I spread the cost over the estimated life of the system (30 years), and compare it to the amount I’m currently paying for my electricity (fossil fuel generated). Hopefully this will provide a real-world cost comparison between fossil fuel generated electricity and PV solar generated electricity.

In segment one of this series I determined my total electricity use for the previous year and the cost of that electricity. The electric power use for the year was 8455 kWh at the cost of $1701.12. This is an average monthly use of 704.59 kWh of electricity at a cost of $141.76 per month. In the last segment I determined the cost of the solar electric system and after subtracting the Federal tax credit and State rebate, my cost was determined to be approximately $23,171 ($41,822 – $18,651 = $23,171).

At $23,171 for the system, divided by $1701.12 (cost of my home electricity for previous year), the payback works out to be just under 14 years (excluding the interest you may have to pay on the initial capital cost). This means that the remaining 16 years in the 30-year life of the system would pay out an additional $27,000 for the homeowner.

Although I didn’t take into account the amount of interest on the initial capital cost, that amount would probably be more than offset by the rise in energy cost over the next thirty years. With the proper care and maintenance you could have your own electrical generator in the home for at least the next 30 years. As for required maintenance, you should try to clean the panels at least two times a year, at the end of the rainy season and towards the end of summer because a 10-15% decrease in solar output can be noted when panels are dirty.

The energy cost and consumption for this analysis comes from one years worth of electric bills provided by an average homeowner. The conclusion of this analysis is that the PV solar system would pay for itself in just under 14 years and then provide, basically free power for the remaining life of the system. The payback of 14 years is a long time, but when considered over the life of the system, the remaining 16 years provide an excellent return on the investment.