Paul Ahrns
Program Director

Paul Ahrns

Program Director

Paul grew up in Nevada City, spending his summers exploring the mountains and valleys around Truckee. His summers in the Sierra fostered his passion for protecting and sustaining the natural wealth and beauty of the Sierra Nevada region. Paul returned home to the region in 2010 to join the Climate Planning team and work on the first phase of the Green Communities Program. Paul has served as a Planning Technician and Project Manager for the Climate Planning team providing technical expertise and project management support to assist over 30 local governments, special districts and private developers with climate planning assistance. Paul brings his experience in sustainability, planning, community engagement and project management to his new role as the Climate Planning Program Director for the Sierra Business Council.

Personal Highlights:

Paul earned his Bachelor’s degree in Environmental Science & Policy from California State University, Long Beach where he graduated Magna Cum Laude and was selected as the Department’s Outstanding Graduate for 2009. Paul combines his passion for the environment and desire to explore the world. He has had the pleasure of exploring 5 different continents and more countries than he can keep track off. The highlights of which have been working with communities in Kenya to drill water wells without using electricity or fuel and exploring the incredible history and culture of China.

Going Solar in the Sierra

Today, I would like to share my personal story of considering solar installation at my childhood home in Nevada City. The house is a singe-family, ranch-style house located in a beautiful neighborhood with mature trees just outside of the Nevada City limits. This is a scenario I’m guessing is quite familiar to residents of the Sierra, considering our region’s ample supply of sunny days and mature evergreen trees.

COMM Blog PA SolarImage 2015 02Our family first considered financing a small roof-mounted system with a local solar company. While we had ample roof space with the optimal orientation and pitch, there was an issue with the level of intermittent shade from the trees both on our property and our neighbor’s. Our options were to cut down part or all of several trees or give up the full generating potential of the system.

As I’m assuming is a common sentiment, we did not want to cut down trees in our neighborhood that provide valuable aesthetic beauty, carbon sequestration and summer cooling from that same shade limiting our solar potential. However, that doesn’t mean we’ve given up! We believe solar is an important strategy to mitigate future climate change and increase our community’s resilience, thus we are still pursuing options for solar. Those options include a power purchase agreement from a local solar provider, individual micro-inverters on a solar system we finance with a local solar company, and community solar. Today I’ll touch on each of these options highlighting some positives and negatives of each, and in future posts will discuss more of the details and numbers as we work through this process.

The constraints of our location made the payback on the solar system we were considering almost twice as long compared to a similar system with full sun exposure. This is only one of a number of reasons why solar might not be as cost-effective at a particular location. According to a 2008 National Renewable Energy laboratory study, only 22-27% of residential rooftop area is suitable for on-site photovoltaic solar systems after adjusting for structural, shading or ownership issues. Hopefully, that percentage will increase as technology improves and solar costs continue to fall.

One option we are giving serious consideration to is a solar lease or power purchase agreement (PPA). Solar leases and PPAs are two slightly different options to purchase solar power based on a set monthly payment that is less than your typical utility bill or a set rate that is less than the market rate from the local utility. Both are designed to offer solar electricity at a lower annual cost than your annual utility bill. The benefits of a lease or PPA include a locked in electricity rate that protects against the volatility of future utility rate increases, monitoring, repair and insurance covered by the provider, zero up-front costs, and guaranteed monthly savings. The down side of both is that you do not own the system and have to share the future savings with the company that owns the system.

Another option we are considering is to either finance or purchase up front a solar system utilizing micro-inverters or DC power optimizers from a local solar company. Both micro-inverters and DC power optimizers solve the same problem for us, which is the loss of efficiency of the whole system due to intermittent shading. They each do this in a slightly different way. Micro-inverters convert solar energy from DC to AC at the module level instead of the traditional conversion that typically happens at a central inverter located near your utility meter. DC power optimizers provide maximum point power tracking at the module level to optimize the DC current produced from each panel and then convert to AC at a central inverter. The main benefit of this option is that we would own the system and be able to reap the full benefit of the solar system. The downside is that we are relying on newer and more expensive technology to counteract the intermittent shading. This drives up the cost of the system and pushes back the payback timeline for the system.

We will be getting a quote from both a PPA provider and a local solar company later this year and I will share more details on how the options compare for our house including the costs and benefits of both options.

The final option, if we decide solar is just not right for the house, is to pursue a community solar option. Community solar was legalized in California last year when SB 43 (Electricity: Green Tariff Shared Renewables Program) was passed in 2013. SB 43 allows participating customers to purchase 100% of their electricity from renewable energy systems located in their region, receiving a bill credit from a renewable project as if it were located on their own property. The bill requires customers to contract through their local utility for community solar to ensure utilities are fairly compensated for the services they provide and non-participating ratepayers do not bear costs from the program. The utility serving our region, Pacific Gas and Electric Company (PG&E), is still in the process of developing their community solar program. PG&E’s current plan is to offer customers a choice to cover either 50 or 100 percent of their energy use at initially estimated two-to-three cents per kilowatt-hour premium. While this might not be the most appealing option currently, PG&E predicts this cost will decline relative to the cost of PG&E’s standard power. PG&E is also developing a separate program that will allow customers to contract directly with a third-party developer for a share of the output from a local solar project. This option is the more typical community solar option in use in Oregon and Colorado. Once PG&E’s programs are developed, I plan to review those programs in a future post.

I hope you found this discussion relevant and interesting; I'm really looking forward to continuing the process. If you have any comments or questions you can contact me at This email address is being protected from spambots. You need JavaScript enabled to view it. or by calling our office at (530) 528-4800.