Solar: Google that!

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Google has taken on the ambitious – Project Sunroof – to map every US rooftop and evaluate the potential for solar to provide each property’s electricity needs.



Easy enough, Google displays the solar irradiance profile for each rooftop by simply entering your address. Then with the dollar amount of your average monthly electric utility bill added, the kilowatts of solar panels required to generate the required electricity are calculated using the most sun-exposed roof surfaces first.

But don’t rely too much on the answer, and here’s why…



The average monthly electric utility consumption (kWh) cannot be entered. Two households could be paying the same monthly amount but consuming different amounts because of their differing consumption habits or electric plans. Time-of-use (TOU) plans will emphasis deferred discretionary electricity use savings by customers minimizing on-peak consumption. Another utility client, less focused on reducing on-peak power, would pay a much higher $/ kWh for the same consumption.

Utility customers not on TOU enter the amount of their current utility bill only to find out that the utility requires them to choose a TOU plan when going solar. Their savings going solar may vary depending their actual consumption patterns. Google simply does not have enough information on the individual property’s consumption to make an accurate projection of savings.

Google specifies only one type of panel for their design and estimate of future generation performance. Using a higher efficiency panel will allow more kW of solar to be located on the portion of the roof with the best sun exposure. Perhaps a smaller panel would better fit the geometry of a complicated south roof, allowing more kW to be installed than Google’s standard panel.

The best panels used today have a better temperature coefficient and lower rate of degradation than the standard Google panel. The result is much higher solar electricity production over panels’ lifetime and much better economics.

Google estimates a fixed $3/kW as the cost for a new solar electric system. Solar is not a one price fits all scenario, since there are many factors and preferences that go into the final cost. For example, the type of roof, sloped or flat, metal, tile or asphalt, old or new, are all going to impact pricing.

Some roofs, such as clay tile will be too fragile to install solar on. Remote rural locations will cost more than urban centers.

Google’s economics make single, fixed assumptions for each of paying cash, financing or leasing solar. Interest rate, terms, utility rate escalation, and discount rate assumed here may or may not reflect your reality. They estimate savings over 20 years, though their FAQ indicate that a solar system will last for 30+ years, hence dramatically underestimating the value of the investment.

Mention is made of a Power Purchase Agreement, PPA, which is typically a fixed or escalating price in $/ kWh based on actual electricity produced. No PPA economic example is provided by Google.



It is respectable that Google provides this service, however, it is likely that your estimated result is either going to be overly optimistic or pessimistic and you will not know which. Simply not that helpful in understanding your property’s solar potential.

So instead of being left wondering, Enriched Solar can provide the accurate answers you require, free of charge!


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