This is caused by the squeegee being angled incorrectly forcing the water under the rubber blade out into the dry area of the glass or from solution being pushed up into the top edge of the window.
Although there is a slight difference between our original calculation and Teslaâs new oneâlast fall we built in a cost of $6,500, Teslaâs current cost for a Powerwall as part of a Solar Roof installation is $7,000.
Step 2: Estimate your cost per Watt installed. Hint: If solar is popular in your state (CA, CO, NJ) and you have asphalt or composite shingles, then use $4-$6/W. If solar is less popular in your state (VA, TX, MI) and you have a tile roof, then use $6-$8/W.If youâre unsure, $5.5/W is about the National average.his calculator assumes no State or Utility rebate. Go to www.dsireusa.org to see if your area offers solar incentives. If it does, subtract it first from the Estimated System Cost. This is your total cost of installation. Then calculate the Fed Tax credit by multiplying the result by 30% (0.3).