There are many reasons to switch to a source of energy that is clean and renewable, such as rooftop solar for homes. The most obvious is that renewable energy reduces your carbon footprint. I still will here people cite misinformation that making solar panels produces more carbon than they save, but this is simply not true. Lifetime analysis of both carbon footprint and energy efficiency indicate that solar panels are better, reducing CO2 by about 80%. This, of course, depends upon the sunlight conditions of your roof, and the mix of energy sources for the grid electricity that goes to your home.

Solar energy also reduces pollution. Air pollution kills about 110,000 Americans every year, and several million worldwide. Further, the direct health care costs caused by air pollution in the US alone is in the hundreds of millions of dollars annually. The EPA estimates that clean air act rules save $82 billion over one decade. Further, studies have found that the total economic costs of air pollution run in the hundreds of billions:

Air pollution negatively impacts the U.S. economy, costing the U.S. roughly 5 percent of its yearly gross domestic product (GDP) in damages ($790 billion in 2014). The highest costs come from early deaths, attributable to exposure to fine particulate matter.

This does not even consider the long term costs of mitigating and dealing with the consequences of climate change. The cost to society is pretty clear, which means that even a massive investment in clean energy is cost effective.

But unfortunately in order to get enough people to change their behavior it needs to be cost effective for them personally, and the shorter the timeframe the better. If you recall, adopting LED bulbs was slowed by their initial high costs, even though they were cost effective over their lifetime. Now the prices have come down significantly making them a no-brainer. The same is true of solar power for the home, but the initial investment can still be high.

One approach (the one I took) is to simply let a company install solar on your roof and you simply buy the electricity produced from them. With zero investment, I simply saw a 20% drop in my electric bill. There are caveats here, however. Make sure the panels do not produce more electricity than you need, because you are obligated to buy all the electricity they produce, not what you use. And – make sure your state has net metering laws so that you get 100% of the value of whatever solar energy you send to the grid. Essentially when you produce more than you use you get credits for what you send to the grid, then you use those credits to pay for electricity you pull from the grid. In some states, however, you may only get 50% credit, which is a ripoff.

You can also buy the solar panels outright, then you get free electricity. This is the best economic option for many (depending on the light characteristics of your roof), but entails a high upfront cost that you get paid back over 20 years. A recent analysis of the true cost and benefit of solar, however, may make you feel better about this. They found that investing in solar (especially solar plus heat pump technology for heating) is a better investment than putting your money in a CD or other savings account. You will make something between 1.7 and 2.6% per year on your investment. If you are a savvy investor this is not great, but it’s not bad either. Many people have some of their money in safe low-yield investments like CDs or bonds, and some of that money would be better invested in solar and heat pump technology.

Further, some states have 2-tiered pricing for electricity. This means when your demand goes over a certain amount on any day the rate increases to a higher amount. Keeping your grid demand below that point therefore saves even more money, and solar can make that happen.

The analysis goes further than that, looking at the overall cost to the the utility company when customers install solar. The initial worry was that grid-connected solar would save the user money, but raise electricity rates for their neighbors. The opposite, it turns out, is true. When customers install grid-connected solar, they reduce costs overall, saving the utility company and their neighbors money. In fact, they are subsidizing the electricity company and not getting properly compensated for it. The authors advocate for a “value of solar” calculation to determine the true impact of rooftop grid connected solar. This includes:

• Avoided operation and maintenance costs (fixed and variable)
• Avoided fuel.
• Avoided generations capacity.
• Avoided reserve capacity (plants on standby that turn on if you have, for example, a large air conditioning load on hot day).
• Avoided transmission capacity (lines).
• Environmental and health liability costs associated with forms of electric generation that are polluting.

What this means is that the purchase of solar panels can be subsidized to bring down their initial cost, making them more affordable to more people. Those subsidies will be cost effective and essentially paid back by the savings of having more grid-connected solar. Everyone wins. Again you will notice that global warming is not even in the calculation. “Liability” costs are estimated, but not the full societal costs of either global warming or the true health costs of pollution. When all of the associated costs are considered, the US alone stands to save trillions of dollars per decade by aggressively installing rooftop solar. Heavily subsidizing residential and even commercial solar is therefore a lucrative investments. It should not be looked on as a cost or expense, but rather an investment (like infrastructure more broadly).

All of these calculations are also based on current solar technology, but that technology is improving every year, getting cheaper and more efficient. So it’s only going to get better. This is low-hanging fruit. We should pick it.