# The future of solar power

1. Aug 24, 2016

### wolram

2. Aug 24, 2016

### Bystander

No.

3. Aug 24, 2016

### Bandersnatch

Yes. One is renewable, the other isn't, so it's a no-brainer. When will it happen, is another matter altogether.

I don't believe the snake oil seller in the ad, though.

4. Aug 24, 2016

### wolram

Do you believe in this spray on technology for glass, if it does work can you imagine a sky scraper with this treatment powering itself?

5. Aug 24, 2016

### Bandersnatch

I'm not qualified nor informed enough to say anything about the tech, including whether it exists or not.

6. Aug 24, 2016

### Staff: Mentor

Do the numbers add? Surface combined with insolation and cells efficiency vs kW needed to run the building?

7. Aug 24, 2016

### wolram

Have you listened to the advert, no figures are given, i would like to know is this technology even exists, if it does then i can imagine a large green house combined with roof mounted solar panels on ones house producing enough power to provide ones needs.

8. Aug 24, 2016

### Staff: Mentor

What I mean is that everyone can try to estimate if the numbers work, regardless of the ad (which I haven't seen - and actually I don't plan to )

9. Aug 24, 2016

### gleem

One thing that bothers me is if the transparency of the windows are not affected then how much energy is absorbed to produce the electricity?

Presently current technology is not that cheap or care free. Currently the average opaque solar cell which absorbs most of the light energy produces about 8-10 watts/sqft of power at full sun and normal incidence. The usual daily sun exposure is generally estimated to be equivalent to 5 hrs/day of normal full sun incidence for a horizontal array of panels. Thus one can expect about 0.045 kW-hrs/sqft of energy produced per day on average. Since an average US home uses about 30 kW-hrs of energy per day one needs about 670 sq ft of panels. One brand of panels is about 10.5 sq ft for that power requirement so you need 64 panels. But this is just to produce the energy that the house uses each day when the sky is clear. The ultimate goals is to be off the grid and produce and store your energy so you need a higher power rating to take care of those cloudy winter days. You may easily need more than twice the number of panels in northern climates.

The storage is another issue. Since it is possible to be without significant sun for several days you need more storage capacity (more batteries). Today the most cost effective battery is the lead acid storage battery and in particluar the 6V golf cart battery (Trojan T105) about $100 ea. These batteries can store about 0.75kw-hrs of usable energy on average.(50% of total capacity) before recharge. The reason you don't use the total capacity is that in doing so you decrease the service life of the battery significantly. Typically when only using 50% per charge cycle the batter may be useful for up to 10 years. Since you may need to run off the batteries for up to three or more days you must not use more than about 17% of their capacity each day. this means you may need up to about 235 ($23,000) of these 6V batteries (14,600 lbs.) and occupy about 121 sq ft of floor space. These batteries have to be monitored for electrolyte level monthly and ventilated for hydrogen release and acidic fumes. You need some accessories such as charge controllers for the batteries, the voltage converters for the AC appliances.probably a PC with power management SW to monitor the production and use of the energy to make sure you use it efficiently. Other issues include monitoring the panels for damage and dirt.

Some day solar power my replace fossil fuel but fossil fuel supplies are still plentiful and cheaper and could last to the end of the century. There is a lot of money in petroleum and the supporting industries which will fight solar adoption too. Perhaps climate change concerns will accelerate the switch over. Problems of too much energy being produced in California during the day has resulted in the power companies not accepting power from consumer solar panels because the grid cannot handle both the companies normal production and that of the energy sold back by the consumer. So the consumer does not get his anticipated payback.

Solar is not quite so clear as it is sold.

10. Aug 24, 2016

It focused on the increase in value of Solar City and Canadian Solar in 2014 at $85 and$41 respectively Today they are today $22.50 and 12.90 respectively. The investment community is not so optimistic as the commentator would lead you to believe.. 11. Aug 24, 2016 ### EnumaElish Solar is as much about transmission capacity as it is about storage. Vast areas of Earth receive sunlight almost year round. Improve transmission and you will not need storage. 12. May 17, 2017 ### nikkkom That would be 10% efficient cell. This was "currently" some 3-5 years ago. Today, "cheap" cells (ones you would buy for a solar power plant, not for comsat) are 20%. 13. May 17, 2017 ### Blank_Stare Let's assume that we accomplish this goal, and perfect a method to transmit electrical power from a PV source, to an end user, anywhere on earth, 24/7/365. OK, I know people will want to argue the above premise, but I am just tossing it out there, so that we can discuss this question: In a global network, at times when demand is less than what is available, what will we do with the excess energy, if not store it in batteries? I'm not an electrical engineer, or energy physicist, so I'm really curious what we would do with that extra energy? What else could function as a buffer to the natural up and down cycles of daily power consumption? Wouldn't we indeed be forced to have some batteries in-line, so we could shut off the PV units that were un-needed, and use the excess power? Wouldn't they be required, in order to accommodate surges, as certain parts of the world that are heavily populated fell into darkness? I'm not picking on you, EnumaElish, I just want to better understand how a global network like you are alluding to could function. 14. May 17, 2017 ### Borek ### Staff: Mentor You don't need batteries to store energy. For an example google for pumped-storage hydroelectricity. There were also attempts to use heated water, compressed air, magnetic fields, hydrogen produced by electrolysis and so on for the storage. Most likely not all of them are practical/viable, but it is not like we lack other options. 15. May 17, 2017 ### zoobyshoe Storage is an automatic consideration with wind and solar for the obvious reason that neither is an "on demand" source of energy. Like Borek said, there are many ways to store energy and, I'll add, more people exploring unconventional ways of doing that than you'd expect. Regardless, I don't think anyone is thinking in terms of the sunny side of the earth powering the dark side. The issue of solar storage is more a matter of simply getting day to power night at normal grid ranges. I also don't think anyone is planning to have solar as the exclusive power source. 16. May 17, 2017 ### Physics_Kid when one resource runs out, another will takes its place. solar maybe, power densities per area are increasing (aka efficiency). surface area for solar are a key constraint. a skyscraper that powers itself?? but only until the sun goes down, then the whole building becomes dark and cold :( the flip side, oil hoarders love solar, why? because solar can offset the massive use of oil thus slowing down the pumping of oil, so instead of$20 billion a month for the next 150 yrs, they have \$5billion a month for the next ~400yrs.

oil will be around for a long time even with the introduction of newer/better technologies in large salt water batteries, solar, wind, nuke, coal, plant fuels, etc.

17. May 17, 2017

### Blank_Stare

Well, that was more or less what I thought, but since I'm not an expert....

I entirely agree... Still, it does create an interesting mental exercise in "What if?"....

18. May 17, 2017

### zoobyshoe

Absolutely. But I'm thinking people are already all over this problem, collecting any and all info about any breakthrough that might be applied to cutting transmission losses in electrical grids.

19. May 17, 2017

### Physics_Kid

grid? i'm thinking large solar mirrors that redirect light to where its needed?

20. May 17, 2017

### Blank_Stare

In fact, however, aren't all of those batteries, of a sort?...Are they not just storing energy for later conversion and consumption? I know our first image, when we hear the word "battery" is a device we plug into a toy, flashlight, or automobile, but just because it isn't electrical in nature doesn't make the water behind a dam any less of a battery... or am I mistaken in believing that it is just a matter of semantics?

I guess the post I replied to sounded to me like we would be able to do away with storing energy, and just use it direct, on demand, generating just as much as we needed.... and I had trouble with that concept, based on the cyclical, unpredictable, and surge-prone nature of energy usage. (I know, predictable within a range, but that takes us back to having too much, or too little at any given time...)

But I think it's clear now.!

Thanks