What happened Shares of solar installer Vivint Solar Inc (NYSE: VSLR) jumped as much as 11.4% in trading Tuesday on news that solar imports wouldn't be as bad as feared. The Trump administration still slapped a hefty 30% tariff on cell and module imports in 2018, but that wasn't as high as petitioners asked for and wasn't a nuclear hit to the solar industry. At 3:45 p.m. EST, shares were still up 6.3% on the day. So what Tariffs on solar panel imports will be 30% in the first year (beginning in February) and then decline by 5% each year after that. In total, the cost of solar panels will rise about $0.10 per watt in the first year, falling to only about $0.05 per watt in 2021 (if tariffs last that long). Image source: Getty Images. Vivint Solar can absorb that cost into its business by raising prices slightly or lowering costs elsewhere in the business; a $0.10 increase on an installation that costs around $3.00 per watt isn't the end of the world. Now what The reaction by the market today seems overdone because Vivint Solar will definitely be negatively impacted by tariffs, even if the negative impact isn't as bad as feared. In general, we can expect 2018 installations to be about the same as in 2017, although there might be a slight decline if marginal markets become uneconomical. Shares may have been up today, but this isn't the time to get bullish on solar installers in the U.S. 10 stocks we like better than Vivint SolarWhen investing geniuses David and Tom Gardner have a stock tip, it can pay to listen. After all, the newsletter they have run for over a decade, Motley Fool Stock Advisor, has tripled the market.* David and Tom just revealed what they believe are the 10 best stocks for investors to buy right now... and Vivint Solar wasn't one of them! That's right -- they think these 10 stocks are even better buys. Click here to learn about these picks! *Stock Advisor returns as of January 2, 2018Travis Hoium has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.