Saturday, October 15, 2016

Part 5 - Making the Decision to Add Solar to our Urban Roof

This is the last of a 5-part series about how buying a diesel vehicle in 2013 resulted in an electric car and renewable solar panels on our house in 2016. 

If you'd like to read all the parts of this series, you can see them here.
Part 1 - How Volkswagen is Helping us Repay the Planet for Its Sins
Part 2 - Our Search for a Cleaner Car
Part 3 - Buying a Used 2016 Chevrolet Volt
Part 4 - A Lesson on Creating Clean Energy at Home
Part 5 - Making the Decision to Add Solar to our Urban Roof

After seeing my friend Claire's photovoltaic (PV) array, I asked around and did some research to see what it would take to have a system installed on our urban home. I found three main solar panel installers. I met a representative from HH at Claire's house (learn more about Claire and her PV system), and asked them to come to the house to see if we had enough sunny roof space to make a viable PV installation. I liked them because Claire liked them and I trust her and because they were offering a group buy discount to anyone who was a member of Fair Share, our local community supported agriculture (CSA) coalition.

However, because a solar array is not cheap (more on this in a moment) I decided this construction decision required a second quote. Full Spectrum is the second company I invited to review our situation. They won the City of Madison request for proposal to be the preferred installer for their MadiSun program. They also had a group buy discount.

Both representatives were pleasant and professional. The Full Spectrum quote came in a little cheaper with a few additional benefits, and he seemed to understand the energy requirements needed to generate power for both the house and the electric vehicle. Being part of the MadiSun program gave me additional peace of mind. I accepted their offer and signed a contract, and sent a respectful note to HH indicating we had selected a different vendor.

The nuts and bolts of installing residential solar


The roof on the "bottom" faces southwest, not ideal,
but not a deal-breaker.
We have a southwest facing roof. In the photo at right, our house i the big one in the upper center. LOTS OF ROOF SPACE.

The ideal roof faces south, but our southwest orientation would work and in fact benefits the utility a bit. Late afternoon in the summer is when they experience high demand for energy use (think air conditioning). A solar array on our roof will produce electricity later into the day than a strictly south-facing roof, generating energy at peak demand times.


We have some shade on the southeastern part of our roof (you can see the shade in this photo) from our neighbors gosh darned red maple (I have harsher words, but this is a family blog). But enough of our roof is clear that we are a good candidate for a PV array.


Full Spectrum charges a Volt from panels on their shop roof.
The next thing was to determine the system's generating size. We provided the installer two years of utility bills to help determine our annual electricity usage. Fortunately, we've had our two roommates for one of those years, so the bills should reflect accurate energy use. We also told Mark from Full Spectrum about the planned Chevy Volt, and he crunched some numbers to figure out how much more energy we'd need to create and how much larger a system we'd need to build to power the car. Our project engineer, Mark, had a good idea about the vehicle needs because Full Spectrum has a Chevy Volt!

Here's how the contract works out:
The installer calculated that we would need to create 6 kilowatts of energy to cover our home and electric vehicle (EV) needs. Here is how we arrived at the final purchase price:
Approximate installation plan.



  • $20,000 for panels, inverters, labor and an extended warranty
  • - MadiSun discount. By attending a MadiSun class on how the program works, we were eligible for this discount. I don't know how much it took off the price of the system.
  • - $2,400, rebate from Focus on Energy 
  • - $6,000, 30% renewable energy federal tax credit. For those who aren't tax accountants, this is a credit against our taxes in the next year. That means if we owed $10,000 in taxes, and the system costs $20,000, we would pay 30% of $20k, or $6,000, less in taxes.
  • $11,600 we have to pay after rebates, tax credits and discounts.

Now, we don't have $20,000 laying around, and even after we get the rebate, tax credit and the discount, we will need to come up with about $17,600 this year until we get the tax credit with our 2016 refund in early 2017.. We decided to take out a home equity loan of credit, which at today's interest rates is relatively cheap money. Still, it's an expense, and we will have about 10 years of payments to make. This will be a new loan, and new loan payments that we didn't have before the solar installation.

But without doing any funny math, I'm about to show you how to make this loan payment go POOF! bye bye. 

Remember those solar panels on the roof and the meter that runs forward and backward? If we size the system correctly, we will make just as much energy as we need each year. This means that the electrical portion of our utility bill will only have a gas charge plus the utility charge to be connected to the electric system. There should be little or no charge for electricity. Our bill will be literally $80-90 less each month. And remember our new Chevy Volt? No gas, or at least very little. Poof! No gas station trips, no money for gasoline.

What this means is that we will effectively send money to our credit union money for the loan and interest, and not send the utility roughly the same amount of money. The loan will be paid off in 10 years, and the panels will continue to produce energy for 20 more years.
This mean we will create emission free energy for 30 years, and cost-free energy for 20 years. Literally, free.

We do have one other expense. Our electrical service (the electric line from the street to our house and the breaker panel in the basement) are just on the cusp of being overwhelmed by the new PV system requirements. When adding circuits to accommodate charging the car we risked taxing the service. So we will pay $1,750 to upgrade to 200 amp service and install a new panel and electric meter. It's something we've thought of doing anyway, and any real estate agent will tell you that 200 amp service makes an older house much more sellable. And, any costs associated with installing PV service are also eligible for the 30% federal tax credit. This means the $1,750 upgrade that will make our house more salable down the road will cost us $1,225.

Let's be clear, you're helping me do this
The things that make this affordable are the federal tax credit, the Focus on Energy rebate and the group buy discount. Yes, we are using YOUR tax dollars to fund this. Another perspective is that I'm using the federal tax dollars I pay to help install sustainable electricity generation on our rooftop, and your tax dollars are going to build roads and fund the military.

Another way to think of it is that all of our tax dollars are going toward generating energy which, with enough residential installations, our local utility won't have to build another power plant (that would cost all of us more in utility rates) or the utility won't have to buy expensive energy during peak demand times because we have people generating energy for them.

However you slice it, this scheme is federally subsidized. Personally, I'd rather my tax dollars going to a distributed energy production system than corn subsidies, bombs or more roads.

Our system will be installed in early November. I'll be sure to write about it and include lots of photos.

If you'd like to read all the parts of this series, you can see them here.
Part 1 - How Volkswagen is Helping us Repay the Planet for Its Sins
Part 2 - Our Search for a Cleaner Car
Part 3 - Buying a Used 2016 Chevrolet Volt
Part 4 - A Lesson on Creating Clean Energy at Home
Part 5 - Making the Decision to Add Solar to our Urban Roof