NEW YORK (AP) Solar panel installer SolarCity is starting to solve a major drawback of solar energy: the sun does not always shine. Solution: large battery pack that provides backup power while reducing electricity charges. Supplier: Tesla Motors, an electric vehicle manufacturer, whose CEO Elon Musk is also the chairman of SolarCity. \"Our goal is to be an energy provider that provides all energy services,\" said lyphirive, CEO of SolarCity . \". Due to the calculation of many commercial electricity bills, the battery will be provided to commercial customers first. SolarCity is also doing pilot projects for homeowners in California, but because the residential bills are calculated differently and the batteries are too expensive, it may take years for the battery to be economically meaningful for the home. \"We know it\'s a long term. So we\'re investing right now, \"said Ryf. Shares in SolarCity rose $2. 83, or 5. 4%, trading to $55 before opening. For power- Even now, hungry businesses can back up with batteries. Many businesses not only charge for the amount of electricity they use for a period of time, but also for the amount of electricity they need from the grid at any time. Think about the car owners spending money on gas to run the engine, and also the horsepower they need when the car is full of people and climbs up the steep slopes. Often, those horsepower fees that are called \"demand fees\" in the power industry will increase rapidly. Solar panels in Sun City can reduce peak demand in sunny times. SolarCity\'s battery pack will ensure that these peaks remain at a lower level when the sun does not shine or customers need a little extra juice. The company said the battery system would reduce demand by 20%. The second benefit: If there is a power outage, if the weather is fine, the battery will be able to run a key system for a few hours or days so that the battery can be charged with solar energy during the day. This is another threat for traditional power companies that are already struggling with weak electricity sales. Efficiency plans and more advanced equipment are already helping customers reduce their energy use, and solar panels and other power supplies are helping customers generate their own power. Now, there are ways for commercial customers to reduce the cost of demand. Other companies offer similar projects to businesses, whether they have solar energy or not, such as Stem in milbray, California. General Electric and Spanish renewable energy company Iberdrola announced its investment this week. The battery provided by SolarCity is the same lithium- Ion vehicles powered by Tesla electric vehicles are reconfigured for fixed use. SolarCity\'s chairman is Elon Musk, founder and CEO of Tesla Motors. Musk is the cousin of the founder, CEO, Lyndon River, and Chief Technology Officer Peter river of SolarCity. In recent weeks, two Tesla cars have caught fire after road debris punctured the battery pack. Tesla batteries for solar backup will be enclosed in steel enclosures and they will not travel along scattered highways at 65 miles an hour. \"The battery is very safe,\" he said . \" Battery systems are also very expensive. SolarCity will not disclose the specific price, but industry insiders believe that the price per kilowatt is close to $1,000. This will make the typical business system more than $100,000. Instead of charging customers for batteries, SolarCity offers them as a service and charges them monthly. They will first launch in higher-demand markets such as California, Massachusetts and Connecticut. The price of home battery packs is around $25,000, similar to the solar panel system itself. Because homeowners do not pay for demand, there is no economic way for the battery to recover the cost. This may change if the price of batteries drops sharply, but they remain high despite years of research and development.