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.
Solar panels normally retail for around $1 to $3 per watt and range between 150 and 350 watts per panel, making the average cost of a single panel between $200 and $350. If you re installing one panel, high-quality, high-output options are ideal.