Solar Panels. The solar panels themselves usually account for about 30% of total costs. Residential solar panels with a combined capacity of 3-8kW typically cost between $4,000-$16,000. The best solar panels are not necessarily the most expensive.Cost per watt ($/W) is a more convenient way of looking at the costs of solar panels. This metric indicates costs relative to electrical power output.The cost of solar panels have decreased significantly over the last decade and are currently selling for under $0.70/W in industrial quantities. For homeowners, this translates to about $1.5/W.olar Panels. The solar panels themselves usually account for about 30% of total costs. Residential solar panels with a combined capacity of 3-8kW typically cost between $4,000-$16,000. The best solar panels are not necessarily the most expensive.