The best-known of these tools is probably the hand-held window squeegee, used to remove the cleaning fluid or water from a glass surface. A soapy solution acts as a lubricant and breaks up the dirt, then the squeegee is used to draw the now water-borne dirt off the glass leaving a perfectly clean surface.
Another way of estimating the cost of electricity would be the cost of an ordinary solar system, or $21,000 as shown in the example above. So the cost of a Tesla retrofit system would be in the range of $33,000 to $37,500.
Purchase price: Tesla Model S and Model X. Base prices for the 2017 Tesla Model S sedan range from $68,000 to $134,500, depending on package; the 2017 Model X crossover ranges from $88,800 to $138,800. Further upgrades are available (more on that below).