A solar installation is an investment. The proper analysis is return on investment. Current actual price before credits and rebates for a 4kW rooftop (16 panels, abt 25 m^2), installed, is about $16,000. This includes a substantial profit for the installer -- it should be available for less in a competitive market. There's a 30% US federal tax rebate, and here in North Carolina a 35% state tax rebate and a ~$1300 utility kickback. Assuming your tax situation allows you to take advantage of the credits, the net cost is about $6000. This will completely offset an annual electric bill of about $2000 - $2500. This is about 35% return on investment. Amortizing the net cost over a lifetime of 15-20 years for various components gives about 30% per year return. This return is tax free. This is an astoundingly good return. Berkshire Hathaway's total return over 49 years is 20% annually.
In other jurisdictions without the state tax rebate and utility kickback the tax-free return is 10 to 15%. Much better than the long-term return of any mutual fund.
Without any direct incentives the return is about 6%, tax free, very safe. CDs are currently about 1%.
Comparing the actual costs is the fair comparison. Apparently TFA omitted the actual government incentives on solar, while implicitly including them in the per kWh utility figures.
Rooftop solar has other benefits as well. Inverters are available that provide power during grid failure (during sunshine), and there are external benefits in replacing dirty coal or dirtier nuke power and slightly reducing the size and power of a monopoly corporation.