Its customers sign a lease or power purchase agreement and pay a monthly fee for the solar electricity from their rooftop systems.

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They will then pay a fixed, monthly fee for using the solar electricity from the panels on their roofs.

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Instead customers a pay a monthly fee to Sungevity for the electricity generated.

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They then pay either a fixed fee or for the amount of electricity produced by the solar panels each month.

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Both allow homeowners to avoid the typical five-figure upfront cost of a solar system by paying a monthly fee that often is lower than their electricity costs.

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Instead of owning their photovoltaic panels they rent them, paying a monthly fee offset by the savings from generating solar electricity.

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Whether imposed on oil or gasoline or electricity or on all carbon fuels, such a user fee would amount to pennies on the gallon for consumers.

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Instead, they pay a monthly fee over a 10 or 20-year contract in exchange for the electricity the solar systems generate.

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