Robco Electric, Inc.

Why am I seeing an increased NV Energy bill this summer after our home solar install?

The $60,000 question.

We have gotten some variation of this question about 1,000 times in the last 3 summers from customers who have had solar for years and are used to only seeing $15 or so on their NV Energy bill.


2019 was the last “normal” year for solar production in the Las Vegas Valley. You can see from the chart in the right the smooth production curve (Blue bars) where solar output peaks during the hot summer months, right as our consumption is also peaking for the year (orange bars).

A parade of Black Swan Solar Events have hit Las Vegas for 3 straight years. As solar pros, we can’t design for these unforeseen extreme events. We can’t even imagine these kind of crazy changes to people’s behavior and the weather patterns happening year after year.

The Black Swan Parade

2020: The Stay-at-Home Year

In 2020, the global pandemic shook our collective world. The widest spread Black Swan event to hit modern civilization since WWII. Starting in March of 2020, the stay-at-home orders spiked power use by about 20% for the average household. Turns out, if people are at home more, they use a lot more power. More TV, more computer, more air conditioning, more vacuuming, more cooking, more everything! Look at the orange bars in the 2020 image compared to 2019. Those measure my house’s total consumption. See the spike in March that lasts all year? My solar system (and all the others in Las Vegas) was making power…but we were all using WAAAAAAAY more power than usual. The systems don’t magically make more power than they were designed to produce, just like the engine in your car doesn’t somehow transform from a 4 cylinder to an 8 cylinder. So, if your power use increased by 20%, you’re going to have an after solar power bill because you’ll be buying that extra power from NV Energy at full retail price.

2021: The Year of Fire Haze and Extreme Heat

In 2021, solar and power use got smacked by a different “Black Swan” event. This one was localized to the Western US and Las Vegas was right next door to the hardest hit region. Most folks had returned to a more usual amount of at home time… but then in the summer of 2021, the west coast was ablaze with out of control wildfires for months on end. The smoky haze from our neighbor’s disaster movie existence settled over the entire Las Vegas valley. Remember those days when the sky was just a glowing orange haze and it looked like we had all moved to Tatooine or Mars? That particulate dense smoke blocked sunlight from hitting the city’s solar panels at the same level it usually does during those cloudless, long sunny days. You can see the noticeable dip in production (blue bars) during the summer of 2021. So, every solar system made less power than usual that year because there was a lot less sunlight to work with. The extreme heat also didn’t help. Power use spiked again over the summer trying to keep folks cool during the hottest summer ever recorded in Las Vegas. So for 2021, you had both LESS POWER being made AND HIGHER POWER DEMAND. Thus, for the second summer
running, we all bought more power from the NV Energy grid to fill the gap.

2022:The Cloudiest Summer in a Decade

Now here in 2022, we have yet another Black Swan event mucking up solar land. This summer had the longest, wettest, cloudiest monsoon season we’ve seen in 10 years! (This here black swan had a silver lining, though, because we sure needed that water desperately!) Again, solar needs clear skies and long sunny days to hit maximum output over the summer and we didn’t get them for most of the summer. Temps were not as extreme as last summer, so we didn’t see quite the same 1-2 punch with reduced production AND higher power demand, but still the effect was enough that yet again a big old dip in the blue production bars over the summer means here we all are buying more power than normal from the grid to fill the gap.

In summary, solar needs clear, sunny skies for maximum power output. The last 3 years haven’t seen that during the summer, so every solar customer in the city is seeing bigger than usual after solar power bills.

If you are concerned about your system’s performance, please get in touch with your Robco Solar Consultant.


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