How To Make Solar PV2EV Profitable

Sonoma Clean Power (SCP) is saving everyone in Sonoma County a little money on their PG&E bill and that’s a pretty big deal, but it’s just part of the story.  In February I purchased a 2011 Nissan Leaf electric vehicle (EV) for $10,000 and in May I switched to PG&E’s EV seasonal, time-of-use (TOU) rate.  Figure 1 is an excerpt from by PG&E bill showing the $80.93 earned since switching to the EV rate.   

Figure 1:  Net Energy Metering Credit and TOU rate showing Peak, Part-Peak and Off-Peak

As illustrated in Figure 2, TOU rates change during the day to reflect the utility’s cost of service during those time periods; the PEAK rate is $0.43/kWh and the OFF PEAK is a dime per kWh.  The PEAK rate would be onerous if we didn’t have PV (solar electricity) but we do so when our PV system spins the meter backwards during the PEAK period we make $0.43/kWh and when the EV charges at night it costs us $0.10/kWh (as illustrated in Figure 3).  PV produces power when the utilities need it the most and prices are high…and electric vehicles typically consume energy at night when the utilities have a surplus and prices are low.   

Figure 2:  Net Energy Metering Credit and PG&E summer EV rate showing Peak, Part-Peak and Off-Peak

Figure 3:  PG&E graph shows power consumption OFF-PEAK and power production (negative value) during PEAK

So the way it looks if we keep up like this at the end of the year we could make a tidy little profit, but there is a problem and this is where Sonoma Clean Power saves the day: PG&E and the California Public Utilities Commission (CPUC) instituted a policy to zero out any credits due to the solar customer at the end of the year (see Figure 4).

Figure 4:  Excerpt from PG&E bill highlighting reset to zero ruling

PG&E provides no justification for this policy in their literature, for example, their “Helpful Guide to Net Energy Metering and the Billing Process” includes a list of “solar savvy questions” but it does not ask or answer the question, “Why are my credits zeroed out at True-Up?”

Fortunately for residential and commercial solar PV system owners SCP does not zero out any credit you may have earned at the end of the true-up period, on the contrary, they reward the PV customer with an additional penny per kWh.  And SCP will pay up to $5,000 in cash for credits earned in a one-year period (while still providing any remaining carry-forward credit for anything above $5,000).  This is what separates a community choice aggregator like Sonoma Clean Power from the investor-owned CPUC regulated utility like PG&E.  The first Community Choice Aggregator in California, Marin Clean Energy, has the same policy as SCP and even better they have no limit on the credit “cash out” if the solar customer chooses that option.

PV2EV Story Doesn’t End There

The energy bill savings is just the tip of the iceberg, what is really impressive is savings at the gas pump. Figure 5 provides a conservative estimate of what we’ve saved at the pump in May and June, a total of $243.  If you add that to the utility bill savings mentioned above it comes to over $300 since switching to the EV rate.   We love solar and we love the LEAF and so far PV2EV results in a profit of over $150/month during the summer months.  Not to mention the 1,800 worry and emissions-free miles we travelled, powered in essence, by the sun.  

Figure 5:  Estimate of savings versus gas power car getting 30mpg at $4/gallon

The LEAF has simple-to-use “intelligence” on board, for example, a touch of the center console screen programs the car to start charging at 11pm when the OFF-PEAK period begins and to not charge past 7am at the end of the OFF-PEAK period.  And the additional benefits of the electric vehicle become obvious when you own one:

1.    No SMOG check tests EVER AGAIN

2.    No Oil Changes EVER AGAIN – saves money, no spent oil to the environment, less hassle and headache

3.    No gasoline EVER AGAIN – this is huge from an environmental, political, social and economic perspective

4.    Quiet comfortable ride with smooth very powerful acceleration, marginally better than internal combustion engine performance cars in many ways – no vibration, no noise – and idling does not exist in an EV

5.    Regenerative braking – the driver of a BMWi3 EV for example rarely uses the brakes as the regenerative braking can be set by the driver to be strong enough to bring the car to a complete stop at a traffic signal without the use of the brake pedal.  Once you have driven an electric vehicle and you get back into a gas powered vehicle you lament every time you hit the brakes…all that wasted kinetic energy…not to mention the wear and tear on the pads which will need replacing.  My family drove a 2001 Prius for over 100,000 miles and never had to change the brake pads thanks to regenerative braking.

EV will continue to evolve and prices will drop in a similar fashion to PV systems which have become affordable and incrementally improved in the past decade in every aspect; modules, inverters, data monitoring, racking, balance of system and manufacturer warrantees.

EV eventually will become a huge part of the Smart Grid providing electric utility grid stability, increased reliability and lower costs.  In addition, battery packs at the end of their useful life in the EV still have capacity and are now being put to use in buildings…an excellent reuse prior to eventual recycling.

Gas powered vehicles meanwhile continue to clunk along and make smog.

Figure 6:  Author’s kids with LEAF and 14-year old solar PV system on roof


SCP provides energy generation services, not transmission, distribution and billing which is still provided by PG&E.  The credit/cash that we will receive from SCP at the end of the year will be for the generation portion of the bill.  We will still get a transmission and distribution credit from PG&E (only up to the point where it zeros the bill) if we continue with our current usage patterns throughout the year.

So given that we have a large home with a pool built when California energy standards were just starting to get serious, making money with solar and saving a bunch by driving an inexpensive and superior vehicle isn’t such a bad deal.  Thank you SCP for your advanced policy on solar derived utility bill credits, it could be a game changer.  And thank you to Nissan for developing the technologically advanced LEAF.

Figure 7:  4-year old PV system with micro-inverters on pool shed roof

If you liked this article please go to the author’s Linkedin page for a free download of his position paper on NetZEROplus new construction in California and an article on the “460 Lucas Circle Project” a profitable net zero home renovation completed in 2009.

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Frank V. Di Massa is a northern California utility consultant helping to shed light on new lifestyle options that have become available and economic due to the diligence, brilliance, creativity and hard work of engineers, scientists, programmers, architects and many others that invent and manufacture the amazing new technology that continues to color our world.

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