How to Revise the Federal Solar Tax Credit

Electrek has a post up that ranks US cities by households with solar panels. Here’s the list:

The city that stuck out to me was Seattle. Seattle? The Pacific Northwest isn’t exactly known for its sun. And, they also have quite of bit of energy generated by hydro and nuclear, so are those panels displacing carbon-emitting energy sources?

The 2016 official fuel mix statistics by the state of Washington for Seattle City Light show approximately 88% hydroelectric, 5% nuclear, 4% wind, 1% coal, 1% natural gas, 1% biogas.

Seattle – like most cities on this list – is a wealthy town, so there are plenty of people who can afford to drop $10-$20k on panels. Especially when they can tap into a 30% federal tax credit.

But, what if we adjusted the federal tax credit by taking a couple factors into consideration? Here are two to consider:

1. How dirty is the current energy sourcing in a given state? Here’s a ranking of states by how much carbon is emitted by generating electricity:

2. How much sun hits each state? Obviously, this can vary tremendously throughout states, but if we just use a state-wide average of each state we can still improve upon a nationwide average. This chart ranks states by solar irradiance where California is the baseline each state’s number show’s their relative solar irradiance relative to California.

If we combine these values, we can prioritize solar incentives based where they’ll have the largest benefit: States with the dirtiest electricity and the most sun. Here’s what that looks like:

Under this formula, Upper Midwest states would see similar tax credits to what they see today. Minnesota and Wisconsin would drop from 30% to 29%. But, things get interesting at the extremes. Subsidies would be cut in half for states that have relatively clean energy sourcing today, like Pacific Northwest and some New England states. On the other extreme, states with relatively dirty electricity generation and lots of solar energy would receive far higher incentives. The most extreme being Wyoming, where solar incentives would increase 7X. Yes, that’s right. Instead of offering a 30% tax credit or solar in Wyoming, we should be offering a 216% credit.

Someone living in Wyoming that spends $20k on solar panels would have their entire project cost covered, plus a check for $23,200 from Uncle Sam. Now that’s an incentive. Wyoming and North Dakota are the two states where we should pay more than the cost of solar panels for every household. Both states have incredibly dirty electricity today.

The incentives should be revisited on a regular basis to take into account shifting electricity sourcing in each state. It wouldn’t be all that surprising if a significant number of people in Wyoming took action to claim such a lucrative tax credit, which would lead to lower tax credits for late adopters.

Land use of Ethanol vs Solar for Vehicle Fuel

I took a stab at trying to figure out how much land it takes to power an internal combustion engine vehicle with ethanol vs what it takes to power an electric vehicle with solar energy.

The links in the embedded spreadsheet show my data sources. If any of these are inaccurate (or my calculations are wrong) please let me know.

Based on what I’m seeing, it looks like it takes a bit more than an acre of farmland dedicated to growing corn to power a single vehicle. That’s based on the amount of E85 fuel it would take, so it would also take some non-ethanol fuel to make that work.

For the electric car numbers, I used a watts/mile figure found on some Tesla forums and a land use calculation based on typical production of panels in large ground-mount systems. This came to 0.015 acres or 652 sq ft.

It seems like it’s quite a bit more efficient to convert solar energy into electricity, transfer that into car batteries, then use that power to turn an electric engine than it is to convert solar energy into plants, harvest those plants, convert those plants into ethanol, transfer that energy into car tanks, and convert that energy into small explosions to turn an internal combustion engine. If my numbers are correct, it looks like it’s around 70X more efficient from a land needed per vehicle perspective.

While this could be looked at from a “what’s the best use of farmland?” perspective, it’s obviously worth noting that solar panels can be placed on a lot of surfaces other than farmland, including places that don’t consume any land, like rooftops.

Another thing to consider: The cost to power an electric car can be significantly cheaper than what’s shown in the spreadsheet if you take advantage of electric vehicle charging and/or time of day pricing plans. Off-peak electricity rates (when your car is likely sitting in your garage) are far cheaper than standard residential rates.

But, wouldn’t that mean that you wouldn’t be using solar to charge your car? Correct. It looks like the future – at least in Minnesota – will involve powering our homes with solar & wind during the day and charging our vehicles with wind power overnight.