updated June 20, 2017

Total commitment outlines the way to eliminate fossil fuel energy use for your home and car by generating your own electricity using solar panels. After that, reduce the rest of your emissions through smart emissions offsetting.

A note from… :
Our goal is to make things simple. We give you the main point in the first few sentences of a page or post so you don’t have to sift through paragraphs of rambling if you just wanted the summary. After that, we elaborate. Don’t have time for all the whys and what fors? Don’t care to read through the supporting research?  That’s not a problem. Just stick to the summary. On the other hand, For those of you who are curious and have the time, keep reading.

All The Facts: 

The first question you must answer on your path to electrical self generation is what source to use, solar or wind. For most people the decision is easy. Very few people live in an area where wind is a viable candidate. If you think wind might be right for you, see my page on wind turbines. For solar, I will cover how to quickly determine if solar works for your location without having to deal with sales people. Next I’ll review the average solar pricing for the nation and share what differences you might encounter in your area. There are several great online tools for easily estimating energy output as well as pricing. Let’s get started.

Solar Basics

Many people in the U.S. can generate their own electricity from a solar array. According to a 2016 report from the National Renewable Energy Laboratory (NREL), the United States could generate 39% of total electrical sector sales from rooftop arrays alone or more than 50% if high efficiency solar panels were used. Additionally, “26% of the total rooftop area on small buildings is suitable for PV deployment.” According to the study’s analysis of every zip code in the United States, you have a high likelihood that some portion of your rooftop would be a viable location for solar panels. Even the very worst locations have a 70% chance that part of their roof will work well for solar.

2016 NREL rooftop solar by zip code

You need two things for a rooftop or ground-mounted solar array to be cost effective.

  1. No shading of the solar array from trees or adjacent buildings.
  2. Flat or south-facing roof or ground area. Southeast and southwest works well too.

To analyze your particular location without staring at a spot every day for a year, let’s take a look at some online tools.

Solar Calculators

By far the best solar calculator is the National Renewable Energy Laboratory’s PV Watts. It also allows you to tinker with various array options: size, location, panel tilt, losses, and others if desired. This will introduce you to the many choices available for your system and allow you to instantly see the resulting output. It is a powerful tool. Let’s walk through the parts of the calculator.

PV Watts Step by Step

PV Watts is a simple interface that will guide you though the process. The first step is to select your city or town. Different locations get different amounts of sunshine. After that, you come to the system info page. One of my favorite features is being able to draw the array size and location. It isn’t required (you could just type in the system size you want to calculate for), but can help determine how big an array you will be able to fit on your roof or other designated area.  Let’s walk through the other options with the screen shot below.

PVWatts screen shot 01

DC System Size: According to the U.S. Energy Information Administration, in 2014 the average annual electricity consumption for a U.S. residential utility customer was 10,932 kilowatthours (kWh). It varies by state from 6,077 kWh (Hawaii) to 15,497 kWh (Louisiana). In Denver an 8 kW system will provide approximate 12,200 kWhs per year. If you followed my recommendation from the intermediate page and converted your home to 100% electricity, then you will use more than the average electricity for your area. You may need more electricity than a rooftop solar array will provide, unless you are lucky enough to live in an area with lots of sunlight year round. By reviewing your electrical bill, you should be able to find your yearly consumption. Take a moment and find your latest bill.

Now that you have reviewed your electric bill, use the PV Watts “draw your system” option on the right side of the screen. Draw an outline of the area where you plan to install panels. If the area is completely free of obstacles such as pipe vents, roof vents and chimneys, then this will give you a very good estimate of possible solar array size. If you do have obstacles, subtract 300 watts per obstruction. (This estimates one less panel. You can use the exact watt number if you know the specific panel type you will be using). Now move on to module type.

Module Type: The default module type is “standard” which NREL defines as a 15% efficiency panel. As of 2016, that is a below average efficiency. Several companies even provide panels that are above 20% efficiency. This can be important if you have limited space on your roof. The more efficient panels will provide you with a greater percentage of your energy needs. Another big difference from panel to panel is the degradation of panel efficiency over time. When you ultimately get quotes from installers, make sure they list guaranteed energy production over the warranty period.  That will allow you to make an apples to apples comparison from system to system. You want to compare the lifetime system electricity production, not the day one electricity production. For module type, select standard unless you know the panel specs that you will use in your system. If you select standard, you will likely not be disappointed by the panel production quoted by the installers you receive quotes from.

System Losses: The standard loss percentage PV Watts uses is 14%. This could change depending on your particular location, but is good enough to get your first estimate, so I recommend sticking with the default.

Tilt: To achieve close to ideal production, you will want to tilt the panels to an angle equal to the latitude of your location. This works well for flat roofs, but panels are mounted flush on angled roofs for ease of installation and aesthetic reasons. These are the tilt angles that correspond to various roof pitches.

Roof pitch - panel tilt


Azimuth: This corresponds to the degree away from due north. The ideal angle to face a solar panel is due south, 180 degrees in the calculator. The further away from due south your panel faces, the less electricity is created. Panels facing southwest will be more efficient in the evening and less efficient in the morning. Panels facing southeast, vices-versa. If you live in a region with lots of sunlight (Phoenix or Los Angeles for example), you can probably even get away with mounting a system on east and west facing roofs. The one thing to always avoid is mounting panels on north facing roofs.

Economics: PV Watts also provides an annual value of energy for the system. Plugging in the cost you pay the utility company allows you to learn the value of the electricity created as though you had paid the utility company instead of generating it yourself.

PVWatts screen shot 02

This allows you a quick way to calculate the payback time for your system assuming electricity prices never rise (spoiler alert, utility prices always rise). Now that you know the amount of money your hypothetical system will save you, it’s time to figure out what you system costs will be.

Solar Array Costs

Solar costs have been dropping like a rock. In the 1970’s a solar panel was more than 212 times more expensive than panels today.  Take a look at Bloomberg’s graph of the falling cost of panels from 1977 to 2014.

1977-2014 Solar Panel Costs

The cost of solar energy is now less expensive than fossil fuels in most cases. Despite this, prices vary across the U.S. In states with a highly active solar industry, costs can be very low. In other states, pricing has not yet caught up. The good news is that as of September 2014, solar was already cheaper than grid energy in 42 of the 50 largest cities in the country. By the fourth quarter of 2016, the national average installed price for residential solar was $2.84/watt dropping by 20% since September 2014.



The costs come down even further once you consider all of the incentives and rebates offered by federal, state and local governments. For instance, the Federal tax credit refunds 30% of the system. This reduces the average cost to only $1.99/watt.  For all incentives in your area review the DSIRE website, a searchable site for all renewable incentives, not just solar. When reviewing costs, make sure that you can use the federal tax credit. Since it’s not a rebate, you must have a tax liability equal to or greater than 30% of your system costs in order to take advantage of the credit.

The next consideration is how to buy the system.

Lease or Own

You will rarely see such strong opinions among renewable energy advocates as you do in the discussion on leasing versus owning a system. The arguments boil down to this: Leasing allows you to have a solar system with zero up front cost and the installer takes care of all of the paper work regarding tax credits. There is a catch though, and it is big. Over the lifetime of the system, people who lease a system will pay a lot more than those who get a loan or purchase their system outright. Plus, many leases include a yearly escalator in the lease agreement, which means the payments increase every year. I would only recommend a leasing option when an individual can not possibly qualify for any other way of purchasing solar (PACE, home equity loan, standard loan, cash).

The benefits of owning a system:

  1. Just like owning your house, the payments are the same every year (with standard loan).
  2. If you solar loan and home loan are through the same bank (or even rolled into the same loan), it eases the transfer of ownership when selling your house.
  3. Many banks are starting to offer low interest loans for solar systems.
  4. You receive the tax credit for the system instead of signing it over to a leasing agent.
  5. PACE programs offer financing with zero money down. However, PACE will include interest. Make sure that PACE interest rates are not worse than what you would be able to get from a bank loan.

At this point, a typical system can save an owner tens of thousands of dollars over the life of the system. If you are planning on buying your array, make sure to look into the PACE program in your state. PACE stands for Property Assessed Clean Energy. State or local governments pay for 100% of a project’s costs and then are repaid for up to 20 years with an assessment added to the property’s tax bill. California, Florida, and New York are among the list of states with active PACE programs. More regions are offering this this type of financing all the time. This is a great zero dollar up-front cost option for financing a large clean energy purchase such as solar.

Now that you know how to generate your own energy, it’s time to talk about all of the other emissions you can’t get rid of any other way.

Carbon Offsets

In our contemporary world, most travelers fly when making a cross country or international trip. That means carbon pollution. I know I feel a little awkward about my carbon footprint, but I don’t plan to stop flying tomorrow. I do want to know what I can do to make those carbon fumes a little less likely to ratchet up global warming. If you feel the same, head over to my Offsetting Emissions page to learn about the good, the bad, and the ugly of carbon offsets. Less time on your hands? Just skip over to our page on Renewable Energy Certificates (RECs) they are likely your best option for decreasing your carbon footprint. We explain here how you can get up to 50% of your energy use from RECs for free.