Solar Power?

[j.p.s]

Originally Posted by Calenorn

Thanks all. Sounds like the power demands in smart phones has grown faster that the ability of solar cells. I got the impression that solar cells are lighter and less expensive than they were, but I guess they haven't gotten any faster.

They have by a lot, just nowhere near as much as the power demands of handheld devices. There were inbuilt solar cell calculators over 40 years ago that would run on office lighting. The total solar cell area was a few square cm. Cheap solar cells are around 3 times more efficient now, but a phone needs around 1000 times more power.

Originally Posted by Calenorn

If I designed the world I would make an eink reader with a solar panel on one side and the screen on the other. Waterproof with a rugged case for camping.

It was tried around 10 years ago, but it didn't pan out.

https://www.mobileread.com/forums/sh...d.php?t=213065

[Quoth]

Solar powered calculators still exist Now about €2. Uses a coin cell too which last about 5 to 10 years.

[theducks]

Originally Posted by Calenorn

but I guess they haven't gotten any faster.

Solar cells have 2 measurable things (time is not one).

Volts and Amps (E*I=P) for a given exposure to sun.

Time is a factor of Power (P) and the ability of the storage to accumulate.
Try and force that (or fail to monitor and regulate) = FIRE.

Be wary of cheap Power banks:
1) They skimped on the charge monitor and regulate.
2) The cells inside are not balanced (have same performance grade)
3) They are excessively discharging at a rate faster than the cells expect for good life. Many batteries spec Wh over an 8Hr rate. Faster provides less Wh. (the internal batteries may be at a higher or lower voltage and the output is buck-boost regulated to 5V (or spec)

4) They just lied about overall Wh capacity

[ownedbycats]

Would've been useful during the power outage. But I'm not sure how much use it'd be in Nova Scotia.

[haertig]

Originally Posted by theducks

4) They just lied about overall Wh capacity

I have an inexpensive small (-ish) 2000 watt generator. But I realize that it is rated in Chinese watts. So I figure I actually have about a 1200 watt generator, with a brief peak capacity of 1500 watts.

Similarly, my power bank is advertised to charge my phone 4 times. The most I've pushed it to is 2 times, regardless of what the "capacity remaining" LED indicator lights say. Then I recharge the power bank.

Once you have given in and resigned yourself to not expect the performance that the manufacture claims, you are disappointed less often.

[j.p.s]

Originally Posted by haertig

Once you have given in and resigned yourself to not expect the performance that the manufacture claims, you are disappointed less often.

A sales rep for high end workstations in the 80's liked to say that performance specs are "guaranteed not to exceed". (That is theoretical maximums unlikely to be approached in actual workloads.)

[ApK]

Originally Posted by Quoth

Solar powered calculators still exist Now about €2. Uses a coin cell too which last about 5 to 10 years.

Many auto-darkening welding helmets have small solar panels that charge/back-up the coin cell batteries that power the auto-darkening filter. I assume the light of a welding arc is enough to provide sufficient power under normal conditions, as long as the batteries have any charge at all. Some popular cheap helmets don't have replaceable batteries, so even with the solar cell, they are claimed to only function for 6 years or so.

[ApK]

Originally Posted by Apache

Most people turning to solar power don't seem to realize that location plays an important role in recouping your expenses. In areas where clouds obscure the sun for a good portion of the year, it can take a homeowner up to 30 years to recover their expenses. In an area where the sun is prevalent you can recover expenses in less than 10 years. Also, in the US you were able to sell the excess energy that you produced back to your local power company. The power companies were required to buy your excess. Funny that now there are more people turning to solar that states are starting to pass laws that exempt power companies from having to pay you for your excess energy.
Apache

I don't know if it has since changed, but when the solar craze started here in NJ some years back, it was also against the law to store the excess power, so no Tesla Powerwalls or anything like that, so you could not use your excess power for nights or cloudy days. It's like they were going out of their way to make it less practical.

[Quoth]

I looked at Solar for the house recently and concluded it was pointless without about 40Ah of 48V batteries per panel. A per panel up converter (it's about 42V max on the panels) for each set of 4 off 12V car batteries (56V fully charged), then diode splitter/combiner for optional mains charging and industrial 48V to 220V AC 2000W inverter/UPS (about 44V to 56V operation) (as used in mobile phone bases, datacentres and telephone exchanges). Cheaper than a grid connected system selling excess to grid. Better value to use it yourself and not sell it. There would never be an overall excess with 6 off standard size panels. It's touch and go without a grant if it would pay back before the panels wear out.

Lead Acid batteries are cheaper than same amount of Lithium and the lead is 100% recycled to new batteries. Lithium only makes sense for portable gear and vehicles. The size and weight is no issue on a UPS or solar system.

I'll wait and see if the grants are improved.

[shalym]

Originally Posted by haertig

Smart phones take quite a bit of power to charge. They have pretty significant batteries in them. Don't equate small size with small charging needs. And a battery pack capable of charging a smart phone in a reasonable time is not going to have a small battery itself. This all can be done, for sure, but not with small solar panels. Be sure and do good research on what will be required to charge the specific devices you are targeting, within the time constraints of how fast you want to charge them. I would take whatever specs the solar panel quotes and reduce those to 1/4 to maybe get a more realistic picture of what you could actually expect out of them in real world conditions.

Interesting. I have one that is very similar to this https://www.amazon.com/20000mAh-Wate...dp/B09NLL41KY/ and it takes about 3 hours to charge if I leave it on a windowsill on the western side of the house (although the battery wasn't totally dead when I started charging). It will charge my phone overnight, with some charge left over in the morning to give a little boost to my Kindle. I then put it back on the windowsill to charge again. I just did this a month or so ago when we had a multi-day power outage. I live in the Northeastern United States.

Shari

[ZodWallop]

Originally Posted by shalym

Interesting. I have one that is very similar to this https://www.amazon.com/20000mAh-Wate...dp/B09NLL41KY/ and it takes about 3 hours to charge if I leave it on a windowsill on the western side of the house... It will charge my phone overnight...

I'm very tempted to buy one of these.

[ownedbycats]

Originally Posted by ZodWallop

I'm very tempted to buy one of these.

Might want to look around at different ones -- ratings seem to indicate the linked one tends to fail quickly.

[Renate]

Originally Posted by Quoth

Lithium only makes sense for portable gear and vehicles.

One of the real benefits of LiFePO4 is that they will accept whatever charge you throw at them. Lead-acid are happy to take a lot of current initially but will gradually slow down in accepting a charge. If you have a gray morning but then a sunny afternoon, the LiFePO4 will fully exploit the capacity of the solar system and fully charge while the lead-acid will slow down and end up not fully charged.

I'm using lead-acid now that are about five years old. I will replace them eventually with LiFePO4, but there is enough capacity so that I can put it off. The little orange dots (peaking at 12:45, local noon) show you the solar capacity. That the red line drops off sharply after 11:30 shows you that the lead-acid batteries are losing their appetite. They still want to soak up more electrons for another 6-8 hours, but if it clouds up, they lose. Yeah, we had some intermittent clouds yesterday.

[Calenorn]

Originally Posted by shalym

Interesting. I have one that is very similar to this https://www.amazon.com/20000mAh-Wate...dp/B09NLL41KY/ and it takes about 3 hours to charge if I leave it on a windowsill on the western side of the house (although the battery wasn't totally dead when I started charging). It will charge my phone overnight, with some charge left over in the morning to give a little boost to my Kindle. I then put it back on the windowsill to charge again. I just did this a month or so ago when we had a multi-day power outage. I live in the Northeastern United States.

Shari

This is what I’m thinking about. I get a week between charges on my Clara as is. Wonder how long it could go with a daily solar boost?

[Quoth]

Originally Posted by Renate

One of the real benefits of LiFePO4 is that they will accept whatever charge you throw at them. Lead-acid are happy to take a lot of current initially but will gradually slow down in accepting a charge. If you have a gray morning but then a sunny afternoon, the LiFePO4 will fully exploit the capacity of the solar system and fully charge while the lead-acid will slow down and end up not fully charged.

Sorry, propaganda from sellers of Lithium batteries.
1) Depends on charging circuit re how Lead Acid charge. Also if nearly fully charged it doesn't matter.
2) "LiFePO4 is that they will accept whatever charge you throw at them." Totally untrue. Once they are charged there is zero charging. Lithium battery life is longer if not absolutely fully charged.

The Lithium tech batteries are less recyclable, use more resources to make and fire / explosion risk is very high if charging HW or SW fail. Lead Acid much safer.

If your batteries frequently get fully charged when loads of daylight left then:
1) If you don't run out of power in dark, you have more batteries and panels than you need.
2) If you do run out of power in the dark, then you need more batteries.