How to choose the right solar panels for your needs

Solar panels on house with rainbow

Part 3 of the Buyer’s Guide to Solar Photovoltaic Systems. Go to part 1>>

As solar cell technology advances costs have been dropping and efficiency soaring. There has never been such abundant choice as now. Choosing the right solar panels can result in a sizeable impact in energy savings over the years, so making the optimum purchase for your needs is essential.

Solar cells come in two main types: crystalline silicon and thin film. Both have their own set of advantages and disadvantages. In general, crystalline silicon technology has been around longer so offers the peace of mind that newer thin film cells do not. They don’t perform as well in extreme heat, nor in the shade as thin film, but are better in cooler weather. Thin film is cheaper and, being a newer technology, is improving rapidly.

Here’s a checklist you can run through to find the best solar panels for your needs:

1. Determine what type of solar cell technology is most appropriate for your application. If you need to re-shingle your roof in the near future, consider solar shingles, otherwise look at standard panels. Refer to the following list when making your decision:

CELL TYPE

CRYSTALLINE SILICON

THIN FILM

Monocrystalline

Polycrystalline

Cadmium

Telluride

CIGS

Amorphous

Silicon

EFFICIENCY (avg.) 14 – 17.5% 13 – 15% 9-11% 10-12% 5 – 7%
HIGH TEMP.

PERFORMANCE

drops 10-15% drops 20% 0% drop 0% drop 0% drop
OPTIMAL TEMP. performs well in cool weather, but poorly in extreme heat performs well in cool weather, but poorly in extreme heat performs well in hot weather, even extreme heat performs well in hot weather, even extreme heat performs well in hot weather, even extreme heat
COST most expensive crystalline silicon cheapest crystal-line silicon cheaper than crystalline silicon—most cost-effective thin film cheaper than crystalline silicon cheaper than crystalline silicon
ADDITIONAL DETAILS oldest solar cell technology and most widely used economical choice due to its cost to performance ratio cadmium is toxic, though very small amounts are used some CIGS panels have posted impressive 20% efficiency figures requires a lot of roof space and can take longer to install than other cell technologies

2. Hop online and check out SolarDesignTool, a great resource that lets you line up solar panels side by side for easy
comparison.
3. Find the prices of your selected panels.
4. Perform a cost-benefit analysis for the panels you’ve chosen. Compare peak efficiency to sales price while taking the warranty period into account. Though one panel may be 25 percent less efficient, if it costs 50 percent less and is guaranteed to last the same length of time, it’s likely the better bet.
5. Measure your roof to establish how much space you have for your panels.
6. After having determined your energy requirements in the previous section of this guide, add up the power ratings, also on SolarDesignTool, for your selected panels to calculate how many panels you need.
7. Write down the dimensions of your chosen panels, then multiply the length by the width for an individual panel to
determine each panel’s surface area in square inches. Multiply that figure by the number of panels you need to see if they’ll fit on your roof or yard.
8. Look into government incentives for solar panels on DSIRE.
9. When purchasing your panels, take the time to thoroughly inspect the fine print of their warranties.
10. Select professionally engineered heavy duty mounting racks. Once you’ve bought your panels, there’s no point skimping on the small stuff. Not only could high winds send your panels flying, but you could be liable for any damages they cause.

Resources

» SolarDesignTool
» DSIRE: Database of State Incentives for Renewables & Efficiency

image: jurvetson (Creative Commons BY)
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