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.
Tesla's $3,000 to $3,500 Powerwall system for homeowners (the price depends on the size of the system, either the 7-kWh or 10-kWh version) may actually cost as much as $9,000âincluding installation and ancillary electronicsâfor the consumer, said Dean Frankel, an analyst at Lux Research in New York.f you can shift 7 kWh of electricity use from peak to nonpeak, you can save $2 a day, Duvall said. If you don't have a time-of-day rate, you value [Tesla's system] based on its use as backup power, and there's not a lot of demand for that.''.