Solar roadmaps have traditionally been all about adding more solar and producing more kilowatt-hours (kWh), but lately the conversation has shifted to one about the value of distributed solar. This necessarily takes the form of a table of positive and negative attributes, so the arguments are over what is included in that table, and at what values.
![](https://pugetsoundsolar.com/wp-content/uploads/2021/03/solarpv_roadmap.webp)
Different Utilities
Washington has 64 electric utilities, so the list of solar attributes and values varies between and within them depending on fuel mix and other factors.
![](https://pugetsoundsolar.com/wp-content/uploads/2021/03/wa-utilities-1024x532.webp)
Different Viewpoints
From a customer’s angle, the first value of a solar kWh = the retail price they pay their utility. In the utilitiy’s view, the first value = a wholesale price. For simplicity, we will set those values aside and focus on a value that customer and utility could possibly agree on, the carbon-offset value of solar (COVOS).
The Time is Now
Gov. Inslee is moving forward with a revised Clean Air Rule to reduce greenhouse gas (GHG) emissions that could open the door to a market for renewable energy credits (RECs) so the time to establish a COVOS for distributed solar is now.
![](https://pugetsoundsolar.com/wp-content/uploads/2021/03/bothell-high-1024x566.webp)
Compare Apples to Apples
If the solar electricity produced is consumed onsite, a reasonable comparison of solar to other generation sources looks at the fuel-to-use path. That would include transmission losses and fuel leakage. A known problem for the climate is that natural gas is mostly methane (CH4), a super-potent greenhouse gas, which traps 86 times as much heat as CO2 over a 20-year period. That’s why many studies find that even a small leakage rate can have a large climate impact — enough to gut the entire benefit of switching from coal-fired power to gas for too long. Unless and until there is a uniform reduction of leakage it is true that {Nat. Gas Electricity GHG Emissions = Coal Electricity GHG Emissions}.
Computing the COVOS
The sub-bituminous coal that is burned at Colstrip for PSE’s electricity produces 2.16 lbs of CO2 per kWh. Add to that 10% for transmission losses and you have a simple 2.48 lbs per kWh delivered.
A combined-cycle natural gas power plant produces about 0.77 lbs/kWh, but if methane leakage is at 3% (a modest amount compared to measured amounts) the CO2 equivalent (CO2e) balloons to 2.68lbs + 7% transmission losses for a total of 2.87 lbs CO2e. If carbon is appropriately priced to induce the reductions of GHG needed to stem climate catastrophe at $60/ton, here is how the math works:
2.87 lbs/kWh = .001435 tons/kWh X $60/ton = $0.086 / kWh, the value of a solar kilowatt-hour for carbon reduction only. That is a good place to start the negotiations for an overall value of distributed solar.