Many prospective buyers of a rooftop PV solar system ask: How much harmful CO2 will we avoid when we go solar? Reliable statistics are available that show how much conventional carbon-based fuel is consumed in the production of a given amount of electricity, measured in kWh. Also, we know how many tons of CO2 are emitted by the consumption of carbon-based fuels to generate a given amount of electricity, i.e. for every 1 kWh or 1,000 kWh (1 MWh) of power. Therefore, if we know the amount of power consumed by a PV solar system in kilowatt hours or megawatt hours, we can calculate exactly how many tons of CO2 gas emissions are prevented from entering the atmosphere by virtue of using photovoltaics renewable energy.
To produce 1,000 kWh of electricity, a conventional power plant using carbon-based fuels will produce 0.706 metric tons of CO2, on average. A photovoltaic solar system will produce the same 1,000 kWh of electricity with zero CO2 emissions. Therefore, if we know the average daily or monthly electric consumption of a residential PV rooftop system, we can calculate the equivalent of CO2 emissions that are prevented from entering the atmosphere over a month, a year, 20 years, or a period of any length.
A photovoltaic residential rooftop system of average size may have an installed capacity of 7 kW/h. If this system receives an average of five hours of sunlight per day, this would produce approximately 7kW/h × 5 h/day = 35 kWh/day × 365 days/year = 12,775 kWh/year. Using the above figure of 0.706 metric tons of CO2 per 1,000 kWh and multiplying that times 12.775 kWh/year would be equivalent to 9.02 metric tons of CO2 emissions that were prevented from entering the atmosphere over the course of 12 months.
If we take the useful life of the PV system as 25 years, then this system would save the equivalent of between 225 and 270 metric tons of CO2. When we multiply this by the millions of systems installed globally, it represents a significant contribution to the reduction of global warming.
To contribute this much to saving the environment while at the same time saving money with every monthly electric utility bill is very meaningful to most homeowners. It’s a true win-win situation.