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The future of solar power

  1. May 18, 2017 #51
    Thank you for the clear reply.
  2. May 18, 2017 #52
    ?? The cells are panasonic, at least the first gen powerwall was. They (tesla) do make and have installed "utility" sized power storage and market it as the powerpak.

    I'm missing the point of "made for mobility" So because the cell has a much better energy density it's made for mobility? imo important factors for a battery is energy density, voltage curve, resistance, c rating and ease of use

    As far as non-mobile installations and cost what beats flow batts? The energy department is supporting/funding both flow batts and Li for energy storage.

    Tesla is making batts already?? news to me. I thought that was why they (Tesla) partnered with Panasonic.
    Last edited: May 18, 2017
  3. May 18, 2017 #53
  4. May 18, 2017 #54
  5. May 18, 2017 #55
    The true value of storage for anyone with PV is a lot higher than the average kWh price. As the cost of the PV drops and users have greater supply in excess of usage that value will become more apparent.

    I realise there are large differences in how electricity is sold dependent on where you live. Here we pay a Service Availability Charge on top of usage, so a close to self sufficient PV and battery fitted home effectively pays much more per kWh than a home totally reliant on the grid. Many are on time of use tariffs, where the evening usage can be double the daytime price - for those it can be financially sensible right now. Note that predictions here are for significant retail electricity price rises, as much as 30% this year, and if that is mostly SAC rises it will shift the balance yet further in favour of battery installations. Most batteries will be still working after 10 years, albeit with reduced capacity that, for a lot of households, will still be adequate. Expect both working life and price to continue to drop as the battery industry develops and expands.

    We are moving beyond renewables being used because of subsidies and other policy support into circumstances where market forces sustain it. Those market forces, combined with shortsighted responses like offering very low prices for PV sold back to the grid or forging ahead with Time of Use metering (both on the face of it, expected to reduce attractiveness of PV - batteries not much figuring into those decisions) continue to strengthen rather than weaken demand for PV and storage.

    The service the grid provides to PV and battery using customers is in provision of backup supply, with ongoing improvements decreasing the frequency and depth of dependence on that backup. Equitable arrangements are needed for accommodating that and make best use of the excess such installations tend to produce; higher prices during weather affected periods where existing fossil fuel plant has to ramp up is reasonable, but again will make improved storage options more attractive. If equitable arrangements are not introduced going off the grid will begin looking increasingly attractive; personally our household is very close to the point where additional batteris and the occaisional use of a generator would be cheaper than paying for an ongoing grid connection. We are borderline for gaining any financial advantage from our PV and batteries installation, but if that price rise does go ahead it will no longer be borderline.
    Last edited: May 18, 2017
  6. May 18, 2017 #56
    Solar panels on residential rooftops is the worst way to utilize solar panels. It ought to be frowned upon by anyone who is pro-solar.

    As you mentioned, a residential install can have shading issues. And few of them will have rooftops in the optimal direction/slope, requiring additional resources for the racks, or just limiting how many panels you can place there.

    Plus, every single installation has to be reviewed, permitted, inspected and have it's own transfer switch. And workers will go to a new site every few days, deal with different roof slopes, gutters, dogs, fences, and on and on. Solar is responsible for more deaths/injuries than nuclear, maybe even coal (on a MW-hr generated basis) - I can dig up the link if needed, from US BLS, IIRC.

    Much better to have an industrial/commercial scale installation. A big-box store, warehouse, and/or large public building (school, library, etc). There's is no shortage of large, flat rooftops in populated areas where the grid is available and energy is needed. A crew goes to one site for an extended period of time, instead of a hundred or thousand individual sites. They work on one flat roof - much safer. Easy to get to for maintenance also. Economy of scale in so many ways.

    I'd consider buying into 'shares' of solar farm like that, long before I would put panels on my roof. I wouldn't need to worry about getting my investment back if I moved. I could buy a share of panels in a locality that had the best combination of available sun, high kWh prices, and the dirtiest grid. That would put those panels to the best use, and provide the best financial and environmental ROI. Everything is so far in favor of solar 'farms', that any talk of residential solar is just silly and counterproductive (exception for the rare off-grid requirement).
  7. May 18, 2017 #57
    I'm not so convinced that putting all of the eggs in one basket is the way to go.

    Every four or five years we have a storm that knocks out the power to tens of thousands of people (Michigan, USA), and lasts for as long as several weeks, before everyone is back up and running. The usual reason for the failure is the infrastructure, namely poles and wires that get knocked out by either wind, snow, or ice, or a combination thereof.

    I definitely am sick of extended blackouts. Aside from the regional occurrences, I have had, on average, a local blackout lasting more than 48 hours, about every 30 months over the past 15 years where I live. Now, a simple battery back-up would have taken care of most of those, but installing a system of batteries to last more than 3 days, is a pretty expensive proposition, and it doesn't take long to start justifying some solar panels, instead of a few more batteries, especially when you consider the potential for the regional blackouts of extended duration.

    If I had the coin, I'd be talking about my solar system, not discussing the merits of having one, wistfully.

    From a purely "economy of scale" stand point, your argument is clearly bullet-proof. On a practical level, there are at least some people who would be better served if the power generation was not super-centralized.

    I live on a "spur", not a grid, when you look at how power gets to me. A few years ago, some automobile driver hit a pole 2 miles from me , at 2 in the morning. Everyone on a line between that pole and the stop sign 5 houses past my house, went without power for almost two days, except folks with the means to generate their own, because the power company has not seen fit to cross-connect our end to the grid a few blocks away from me, where there is another "spur".

    I guess what I am saying is that there is no "one size fits all" solution for Solar infrastructure. In my case, I'd rather be self-dependent, than rely on some bean counters to decide if building the infrastructure properly is "cost effective".

    Also, I would hate to think of what would happen if a big-box store that was providing the real estate on their roof caught fire, and the solar farm was lost. We'd be talking about a lot of people with no lights, for an extended period. If it took an extended period of time to build in the first place, imagine how long it will take to clean up the site, and then remove the damaged portions of the farm, or all of the farm, and rebuild it... the red tape alone would be a nightmare.

    ...and that's an awfully large basket of eggs, I think.
  8. May 18, 2017 #58


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    Coal is worse.
    US coal is ~25 more deadly than rooftop solar, which is 4000 times (sic!) worse than US nuclear power. All per kWh of course.
    If we take the global average and include all accidents, coal kills 250 times more people, while nuclear power has 5 times lower death rates than rooftop solar.
  9. May 18, 2017 #59


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    That's definitely a problem, but unfortunately, residential rooftop solar won't solve it; The vast majority of residential rooftop solar installations are not allowed to operate during a blackout.
  10. May 18, 2017 #60
    There are other ways to get residential backup power, they might (probably?) be more cost effective than solar and batteries every few years (natural gas/propane generator). But that's an individual situation for you to make the call on. I was really talking more about regular day-day power generation, not back up power.

    Thanks! :smile:

    Nah. There are two large installations near us, on large school buildings, LOTS of roof space covered with panels. There are 1,760 panels on the roof, yet it has a peak capacity of ~ 440 KW. That's KW, not MW. A typical coal plant in Illinois has a capacity of ~ 800 MW. So losing one building like that would be like losing 1/2000th the capacity of a coal plant (and only when the sun is shining).

    The eggs would be in thousands of baskets.
  11. May 19, 2017 #61


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    The 80 MWh Mira Loma battery facility is for grid transients. It does not qualify as utility 'storage' in the sense of pumped hydro storage plants. Twelve Mira Loma plants would be required to back up *one* large (GW) sized thermal plant or wind farm for *one* hour. There are no battery based utility scale storage facilities anywhere the world, nor any planned, that could back up one middling 500 MW power plant for a day.
  12. May 19, 2017 #62


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    All the eggs are crushed every night.
  13. May 19, 2017 #63


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    So far as I can tell, there are no common residential homes in the US (typical sq footage, not a woodland shack) that can run off the grid for 2 to 3 days anytime of the year using just batteries, no combustion generator behind the curtain.

    Off the grid doesn't work with solar. And, once you need the grid, some 3/4 of its cost is just the maintenance of the infrastructure. Actually shipping power is an afterthought. So, those with residential solar and net metering plans who avoid those costs are simply pushing the grid costs on to their neighbors. That practice is beginning to end in the US.
  14. May 19, 2017 #64
    This does not happen in Europe since a lot of electrical lines here are underground and thus are well-protected against weather. I'm guessing it's used more in a denser-populated areas where cost of land is relatively more important, and also in places expanding grid capacity at some point forced it underground because above-ground expansion was not possible.

    I take it this is economically unattractive for sparsely populated areas of US, since lines are longer while customers are fewer?
  15. May 19, 2017 #65
    Some semantic work there on "utility storage". A journey of a thousand miles begins with a single step, "According to market research firm IHS, the energy storage market is set to “explode” to an annual installation size of 6 gigawatts (GW) in 2017 and over 40 GW by 2022 — from an initial base of only 0.34 GW installed in 2012 and 2013."

    Comparing the energy production of a traditional power plant to the storage capacity of current tech batts. Why must a battery be able to support a days worth of energy from said power plant? Such storage could be done locally, even down to a per person...this flexibility is appealing.

    There are a number of MW storage facilities being built and running all over the world. China, Japan & California seem to be throwing money at this...presumably to further improve/demonstrate the technology.

    I suspect the reason the industry is not planning to build a storage facility capable of backing up one middling 500 MW power plant for a day is because it makes MUCH more sense to scale up...such a bizarre argument. "There are no manned space ships capable of travelling to Titan nor are any planned...ergo not possible."

    Once government funded projects demonstrate the economics the industry grows....and grows and grows.
    Last edited: May 19, 2017
  16. May 19, 2017 #66
    Rooftop installations on big box stores ,warehouses and public buildings will most likely only provide power for those structures. facotries that may have access to adjacent land will probably only produce a fractions of their needs. As a example a factory near me just built a solar facility 1.57 MW, producing about 2.3MWhrs per year on 6 acres (4992 panels) produces only about 12 % of their needs. One MW of power will meet the need of only about 70- 100 residences.

    One could consider municipal solar farms. A community with 5000 houses would need about 60 MW of panels for just the residential requirements add to that commercial and municipal needs. The area needed would be similar to say an additional land fill. It could be funded by bonds and

    I don't think solar is a good option for blackout in a place like Michigan especially when many will be in the winter when output is minimal. You can go for weeks without significant sun. Better with a standby generator 16kW about $3500 https://www.electricgeneratorsdirect.com/power/generac-11kw-16-kw-home-standby-generators.html

    Did a quick calc for a 1 GW, 4GW-hr storage facility using Tesla POWER PACK batteries. it would take 20,000 POWERPACKs occupying a building roughly taking up 4 acres and 5 stories high. From pictures of the Mira Loma facility it looks like the batteries take up about 0.25 acres with the transformers and other equipment taking up another and the power lines towers taking up ? all this fits on a 1.5 acre site.

    The Mira Loma plant provides 2500 houses back up for 24 hours producing 20 MW of power (50kW x 396 bat) with an energy storage of 83,000 kW-hrs. which for 2500 houses is about 33kWhr which is reasonable. A 1 GW facility which is 50 times greater would provide those same houses with 50 days of power. or
    125,000 homes 24 hours. and take up at most 75 acres probably significantly less. However such a facility might cost as much as $900M .
  17. May 19, 2017 #67
    It's not clear to me what your point is?

    What difference does it make who is "using" the output of the solar panels, or what % of their usage those panels represent? An installation of X MW will offset that much grid power, regardless of who is using it.

    BTW, I think you meant 2.3GWhrs (not 2.3MWhrs) per year. 1.57 MW * ~ 5 hours/day * about 300 sunny days/year is about 2.3 GWhrs/year.
  18. May 19, 2017 #68
    I got the impression that there was a thought of using the large roof areas of large area commercial buildings to produce excess power which could be diverted to residential use.
  19. May 19, 2017 #69
    The thought is to use the large roof areas of large area commercial buildings to produce (solar) power (period). It just goes into the grid, there's essentially no difference to the grid and the power plants between 1,000 panels on a big flat roof in the neighborhood, or 2 panels on 500 houses in the neighborhood.

    The important difference is that it will be cheaper, faster and safer to do one install on a big building, and very likely to get more power from the same number of panels, because they will all be at the optimum angle on a big flat roof, with no shade trees. Economy of scale will come into play at all levels (fewer transfer switches, optimally sized inverters, etc). Maintenance on one site is far easier (and likely to be noticed and repaired quicker) on one big install versus 500 small ones. And over 10-20-30 years, guess how many trees will grow and shade some of those panels installed earlier?
  20. May 19, 2017 #70
    I got that and you are correct. Many large local facilities obviate a number of problems.
  21. May 19, 2017 #71


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    In towns, the lines are typically underground, but the big distribution lines between towns are in the open air as everywhere in the world. We just don't have so many bad ice storms and probably more redundancy in the network.
  22. May 19, 2017 #72
    But what point were you trying to make about the commercial building using all (or most?) of the energy the panels would produce?
  23. May 19, 2017 #73
    .That the panel arrays takes up all the available space for their own needs and they cannot produce any excess power to sell to the utility.
  24. May 19, 2017 #74
    And again, what difference does that make?

    A) If a set of panels on a commercial building produce exactly 1 MW at noon, and the building is consuming exactly 1 MW at that time, the power plants on the grid produce 1 MW less to feed that grid than if there were no panels.

    B) If those same panels are scattered across hundreds of houses, and we assume (maybe incorrectly), that the houses are not consuming all that is produced, the net effect is the same. The power plants on the grid produce 1 MW less to feed that grid.

    I see essentially no difference between the power being consumed at the point of solar generation, or consumed by others nearby on that grid. I say "essentially", because consuming it close to where it is generated will reduce transmission losses somewhat, another plus for commercial installations.

    You seem to think there is some advantage to it being scattered across many homes. But I do not get your point.

    Other than the losses I mentioned, there is no connection between the roof used to generate the power, and how much consumption is under that roof, they are just separate things. The grid doesn't 'care' if the solar panels were put over land where no electricity was being used, or put on the roof of a manufacturing plant that uses more power than the panels produce. The end result is the same.
  25. May 19, 2017 #75
    If the panel where scattered and only half of the power generated where used the panel owners put that on the grid and get paid the going rate for electricity generators. So when you are not home your panels are making money.
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