This is a 40 Watt Mono-crystalline Solar Panel and 12V Charger. You could be eligible for up to $2000 of energy rebate in California and some states for converting your home power to solar. Please check with your local utility company. The solar panel is waterproof. The working voltage for charging is 17.2V. If you need to use it to charge a car battery, you may need a charge controller to prevent the battery from overcharging. Connections included: alligator battery clamps. There are three types of Solar Cells on the market. All our Solar chargers use the best - Mono-Crystalline Solar Cells. Amorphous or Dual Junction Solar Glass are the cheapest but are only 7% energy efficient and have 5 years of service life. They are big and heavy. Poly-Crystalline have 25 plus years of service life under direct sunlight and are 13% efficient. Mono-Crystalline have 25 plus years of service life and are up to 20% efficient. This is the same type used in solar car racing. This type of solar cells is now in a worldwide shortage because only a few companies can manufacture these solar cells.

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