Best practice says to focus on the energy efficiency of a building first to lower energy demand, and then, once the demand is low, add renewable energy. Having completed the insulation recommendations from the Home Energy Squad visit, installing solar PV on our roof seemed like a logical next step. Our site is pretty good for solar with a couple of drawbacks:
the house itself is 2.5 stories tall and is unshaded by any trees or surrounding buildings
the house is oriented east-west, providing decent southern exposure
the garage also had decent southern exposure
the south dormer was an unfortunate obstruction, but we could put panels on the east and west faces
the chimney was also on the south side of the roof, thereby taking up space for panels and providing some shade
Install
The project was to put a 9.3 kW system consisting of 33 SolarWorld 300 watt PV panels on the property - 10 on the garage and 23 on the house, with an underground conduit connecting the two. We have a SolarEdge10000 grid-tied inverter with DC optimizers. The pictures below show some of the delivery, trenching, and the final results.
Tracking
With our installation, we were given an Egauge tracking system allowing us to monitor the output of the array. Feel free to check out how it's doing right now!
Long story long:
As soon as we bought a property, I wanted to make it as green as possible. This desire came from a moment in college when as an environmental and natural resources engineering major I realized that energy production and transportation contributed to virtually every environmental problem – habitat loss, climate change, water quality, air quality, etc. This motivated me to commit to greening my energy as soon as I had the chance. I also wanted to show others that going solar in my neighborhood is physically possible, financially feasible, and just plain cool. As such, my goal was to build the largest solar array possible on the property. Peter was supportive of the idea of going solar as well. As he has Environmental Science and MBA degrees, he certainly sees both the environmental and financial benefits of going solar. Our house situation is a bit different than many other residential solar installers in that we have a triplex, and we live in one of two units. The prospect of providing renewable energy to people who were not entirely sustainability-minded seemed like a really awesome introductory point. My goal was to provide them renewable energy at roughly the same cost that they had been paying Xcel. Being a triplex also made this project more financially viable. Our tenants are sub-metered, and we charge them a flat rate for electricity. Using Xcel’s Benchmarking Tool, I was able to decipher what their average monthly bill had been. With that I back-calculated the $/kwh charge. It was important to me that they are still billed per kwh and not a flat utility fee, because I still wanted to make sure there was in incentive for energy efficiency. Incentivizing prudent energy use behavior is also important to me.
Our installation experience was ultimately less than ideal. I won’t go into all of the issues, because that isn’t useful for a case study. However I’ll give you a snapshot, so you have a sense of the difficulties multi-family properties in going solar. Having a triplex with three meters made understanding the options complex for our installer and for us. Xcel was not particularly speedy nor very responsive to our questions either. It was critical for us to understand the order in which we consolidated the meters (or not) and installed the panels, and due to misunderstandings, we ultimately got this wrong. This and the length of time (11-months) from which our panels were initially sized (which was based on electric consumption of previous tenants and after we had had a HomeEnergySquad visit with all new LED bulbs installed), caused us to lose our Solar*Rewards eligibility. Our array had become too large, as the new calculations showed that we would produce over 150% of the annual consumption of the house. Luckily, we were financially able to make this work, but it increase our payback length. This taught us that when we build another array (we plan to continue to do so on other rental properties) we will plan ahead for SolarRewards. If we want to go that route (I don’t like giving them the RECs, so we’ll see if we want (or financially need) to use that program), we will be energy hogs for 12 months, so that we’ll be able to build the largest array possible. The program incentivizes that. It’s bad design. Other issues were that our 1920s-era garage needed structural reinforcement and that we had to have a trench dug under part of our driveway to connect the house and garage.
Ultimately, we had solar panels installed on the roof of our house and on the garage. Since installation we have had no problems, other than snow collecting on the panels, especially on the gentle-sloped garage roof. From this experience, we realized that there are major benefits to going solar in this area of the city: 1. Most of the houses from the 1880s-1920s era are 2.5 to 3 stories tall, which make it more likely that a roof will not have shade from trees and 2. Many of the houses are long rectangles from east-to-west, meaning that they have large southern facing roofs (if there is no dormer). We had the solar panels installed in October, and they were ultimately connected in February. We’re coming up on our 1 year anniversary of Feb. 13th! To date, we’ve produced a net 143% of our consumption, and I sincerely doubt that we will ever pay a bill to Xcel Energy again. December was the first month in which we used more electricity from the grid than we produced, and since we’ve banked so much in credits in previous months, the amount that we have to pay will be deducted from those credits.
To pay for the system, we utilized two loans available from LHENA – the 3% home loan that is available up to $30,000 and the Green-Matching Loan, which provides a $4000 loan with a 1:1 match. The Green-Matching Loan is unique in that if we own the property for a certain amount of time (I believe it is 5 years), then the loan becomes ‘forgivable’ – meaning it becomes a grant and we do not have to pay it back. Overall, LHENA loans are very simple to understand, the process is easy to complete, and the loans offered are very appropriate for solar installations. We also plan to take advantage of the income tax credit this year. Ultimately, it will take us 11 years to pay off the system (which factors in many things, including an average 2.2% annual rate increase for the tenant spaces). That long period shows that our system may not be the best investment; however, it is accomplishing our goal of producing the most renewable energy on our little plot of land possible.