flacaltenn
Diamond Member
We know how to approach the theoretical max efficiencies for solar PV design. We knew that YEARS ago. A panel built from Gallium Arsenide vs silicon crystal would get us to within 20% or so of the physics. But that would mean TONS of arsenic and a doubling of cost versus growing silicon crystal. Sometimes -- the theoretical limit doesn't yield a product.
The issue of inefficiency is more difficult to overcome. Even with panel efficiencies climbing (slowly now compared with 10 years ago), the installation math for a daytime peaking only system has to be rated almost twice as neccessary to guarantee a minimum power requirement. That gets you thru weather related difficulties such as clouds, preciptn, and sun angle thru-out the year and efficiencies related to converting DC power from the panels to AC for the home wiring and selling back to the grid.
So you BUY more panel than you end up using.. And "off-grid" installations are a whole 'nother animal, requiring tons of battery storage and the eco implications of that. A "off-grid" supermarket would require a tractor trailer full of battery storage to make it thru the night and an installation "overdesign" by a factor of almost three.
The grid load in California at 10PM in the summer is 80% of the load at 1PM. That means that PV solar could provide a MAX of 20% of daytime peaks. That's why you see the mandates for 20% renewables by 2020 and all that nonsense. You cannot turn off nat gas, coal, nuclear plants like a light switch. So there is duplication of spending for the MAIN sources of power. Would we reach 20%? Not likely because of geography, grid design, ect...
So you're right. It's time to put up or STFU.. Government should NEVER be subsidizing run of the mill stuff that's already designed. It actually stifles the perfection of tech, because the subsidy warps price to prefer larger markets at the bottom price. If they want to play market makers, they should only fund R&D for increased performance, or new technology. And the solar market NOW is anything but new technology.
I challenge the bold part above, link? Second off, 1PM is not peak time, that is usually considered to be between 4-6pm. And third how do you figure that this even concludes that you could only use 20% during peak? Comparing using solar during the day vs not being able to use it at night makes no sense. Theoretically California could use all their day time electricity through solar panels, and switch to other uses at night.
The factoid came from daily charts that I watched in Cal to predict brown-outs at my company. Specifically from the CA Indep Sys Oper (CALISO), the bozos tasked with waking up each morning and trying to find power a state that OUTLAWED long term contracts. Anyway.. You can view the hourly Load management at
California ISO - Todays Outlook
Be aware that this IS NOT peak summer, it IS a weekend, and NOT that typical summer day that I described. Depending on when you view it will give different results. I HAD to study it for years to protect one of clients from losing experimental data. My observations ARE correct for MOST summer days/nights in Cal. Although I did leave out the WORKDAY qualifier which was what I was most concerned with in the 3rd world of Cal Silicon Valley.
PEAK SUMMER LOADS are the "best case design" for any scenario involving solar when considering the swing from day to night.. And 10PM is the "evening peak" in most all load charts. Look it up..
Furthermore a report came out earlier this year that showed how the entire country could switch completely to green energy by using most of the daytime electricity through solar. .
REALLY? the ENTIRE country? Folks in the NorthEast will be very employed sweeping snow loads off panels won't they? Even tho the installed capacity would have to rated at more than TWICE the average PEAK SUMMER LOADS to guarantee that promise due to weather variations and sun angles? And that you'd be shedding MORE than 1/2 of that produced capacity during the peak summer to waste?
You need to be careful with naive scenario pronouncements such as this that have little connection to hour by hour, month by month variations in demand. But such is the "religious fervor" of the addicted..
Supplementing is with wind power, that can run during the day and through part of the night, and finally, since neither of these store electricity, using hydro electric to provide for power at night, and in case of any shortfalls in solar (clouds) and wind (no wind), since hydro electric stores electricity very very well (all the water behind the dam is potential energy that can be used at any time).
Left out of this "analysis" is the energy and inefficiencies associated with PUMPING that water that requires a HUGE over capacity of wind/solar to run the "storage". Again causing severe economic issues with land usage to site those generators, provide basins for the storage and all the enviro consequences associated with that. Doesn't work in Kansas or much of the flatlands too well either. Actual engineering considerations for where and how frequent these opportunities would be are staggering sober -- compared to your raw enthusiasm..
The real reason that they said 20% by 2020 is simply cost. To switch the entire country, the upfront cost would be in the hundreds of billions, if not trillions of dollars. Sort of like building every power plant in the country all at once. Then you add in that tens of thousands of power plant workers would be laid off in the period of time, and the idea is just not good. Basically what that 20% figure represents is, all new sources of energy should be green, that way no one gets laid off
Bull -- the percentages are based on actual math science using the RELIABILITY, load cycle demands and opportunities to propose a mix that actually works -- NOT COST. When trying to balance wind/solar with the back-up MAIN power generators that must stand idle waiting to be used (nat gas, nuclear, coal, hydro, ect.)
Speaking of wind -- take a gander at Figure V-F in the CALISO report at:
http://www.caiso.com/Documents/2005SummerAssessmentReport.pdf
Wind only available on 4 of the 10 peak summer 2004 days. It only exceeded 50% of AVERAGE capacity on only 2 of 10 peak days.. That's AVERAGE -- not even peak capacity.
That's a LOT of jobs just managing the REAL generators that have to be jerked around to make wind power look useful..
You cannot melt the grid down for 2 hours a day for renewables and switch the other generators on/off like light bulbs..
So if you have articles pretending to claim this is solved.. By all means please share.