Fun with exponents

On 6/12/2020 10:38 AM, Jeff Liebermann wrote:
On Fri, 12 Jun 2020 13:02:10 -0400, Frank Krygowski
wrote:

My wife is addicted to those little solar powered garden lights: solar
cell, Ni-Cad battery, LED, sometimes a switch, and maybe five electronic
bits.

These daze, most use NiMH batteries, not NiCd.

So one of my hobbies is fixing them when they stop working in a
year or two. First it's cleaning and protecting battery contacts, then
bypassing the switch, then maybe replacing a bad battery, then stripping
for parts.

Every day, the sun charges the battery to full, and every night, the
LED discharges it until the battery is fully discharged. Neither NiCd
or NiMH can survive many such cycles. When hot, both are good for
about 500 charge cycles. When cool, about 1000 charge cycles. That
would produce a battery life of two or three years, which is what
you're seeing. Just replace the batteries and start over. They're
cheap on eBay at about $1.00/ea or sometimes less:
https://www.ebay.com/itm/113840263323

snip

Since those solar powered garden lights cost $1 at a dollar store, or $2
at Harbor Freight, probably spending a lot of time and money repairing
them is not the best use of time. Paying $1 for just a battery isn't
such a great deal.

Frank Krygowski wrote:
On 6/12/2020 12:05 AM, news18 wrote:

Bike content;who was that bicycle rider thaty roamed USA with solar
panels on a two wheel trailer. He had computing witha solaris system,
input by a three() key system and when has had surplus power, he could do
CB?

This guy:
https://www.cyclingabout.com/heavies...ever-behemoth/



His entire setup could be reasonably reduced to an iPhone, a Bluetooth
headset and a hub generator today.

On Fri, 12 Jun 2020 13:37:01 -0000 (UTC), news18
wrote:

On Fri, 12 Jun 2020 11:48:06 +0700, John B. wrote:

On Fri, 12 Jun 2020 04:05:47 -0000 (UTC), news18
wrote:

On Fri, 12 Jun 2020 10:40:27 +0700, John B. wrote:


Another question? What is the "service life", or what ever terminology
they use, of your panels?

That depends very much on the particular panels you buy. In all the
reading I've done, the general rule of thumb is quality panels are worth
the investment and most installations areArtemis Fowl new and not
facing replacement
and so the final life is still being determined. Hint,read a few
community PV forums for local offerings.

Stay away from second hand panels, even if free as the installation cost
is the same for second hand as for new.

Also, how do you define service life, aka % degradation you can accept.

I believe that solar panels have a "life till decreasing to some
specific output", which is why I phrased the question as I did.

And the "life" is defined by when output stops meeting your needs.aka
will vary between installation.


You missed the part that said, "Largely because on a sail boat there is
limited space to mount the panels"?

Err, nope, I know how little space therer is on various sailing boats. As
it has been tod to me, the PV on sail boats was just to trickle charge
the batteries to keep them from self-discharging flat and was never seen
as a significant power source.

Generally speaking, on a cruising sail boat the solar panels are one,
usually, of several battery charging systems. It is quite normal to
see both solar panels and a wind generator on the stern of a cruising
boat and, on a larger boat, there will be the auxiliary generator and
of course the main engine has a generator system.

People that used both solar panels and a wind generator told me that
"most of the time", when making a passage, that the panels and
generator were all they required.
--
cheers,

John B.

On Fri, 12 Jun 2020 13:02:10 -0400, Frank Krygowski
wrote:

On 6/12/2020 1:06 AM, John B. wrote:
On Thu, 11 Jun 2020 21:46:02 -0700, sms
wrote:

On 6/11/2020 8:40 PM, John B. wrote:
On Thu, 11 Jun 2020 20:02:26 -0700, sms
wrote:

On 6/11/2020 3:48 PM, John B. wrote:
On Thu, 11 Jun 2020 08:18:31 -0700, sms
wrote:

On 6/10/2020 8:27 PM, Jeff Liebermann wrote:

snip

My monthly use of electricity was going down steadily mostly by
replacing power hogs with more energy efficient devices, such as LED
lighting. However, my monthly use has increased in the last few years
because I've been spending more time at home. Meanwhile, the cost
curve has been neatly compensating for my reduced consumption
resulting in an almost constant dollars monthly bill from 2008 to
2016.

When I put solar panels on my roof my monthly cost went way down, some
months it's zero. PG&E is one of the few remaining utilities that
credits you the RETAIL value, including delivery costs, of the excess
KWH you generate, each month. You don't get cash for that extra
generation, but it is used in the months with less hours of sun when you
can't generate as much as you are using. So you size your installation
so you are able to generate about as many KWH as you use over a 12 month
period.

Out of curiosity, how much did it cost to buy and install your solar
panels and over what period will you actually recover these costs.
And what is the service life of your solar panels?

And do you have a battery bank and inverter and if so what are the
average costs per unit of time?
--
cheers,

John B.


The payback estimate was 8 years (I did an extensive spreadsheet to
calculate this). The cost was a lot, about $17,000 IIRC (after rebates
from the federal government). It's reducing my electricity bill by
$150-225 per month, depending on the month. I have a swimming pool whose
pump is largest year round electric device. A/C is only needed in my
area maybe 3 weeks out of the year and most houses in my area don't have
A/C but it was here when we bought the house twenty years ago.

The cost of my system was higher than usual because a) I used
high-quality, high-output panels to reduce the number of panels needed,
and b) because I have a tile roof which makes the installation more
difficult than if you have a composite roof or wood roof.

No battery. Having a battery would not be a good deal economically
because you're better off selling peak value KWH back to the utility
than using the KWH to charge a battery for night-time KWH. If we had a
large number of power failures it would be different in terms of having
a battery, but power failures in my neighborhood are rare.

Another question? What is the "service life", or what ever terminology
they use, of your panels?

My experience with solar was on a boat and while it worked it wasn't
sufficient to actually "power" the boat. Largely because on a sail
boat there is limited space to mount the panels.
--
cheers,

John B.


I got the monocrystalline high-efficiency SunPower panels with a very
low degradation rate (0.25% per year, compounded), so over 20 years
that's about a 5% loss. Probably everyone exaggerates their degradation
rate a little so maybe 8% is more reasonable

That sounds much better then what I was used to... of course it was
nearly 20 years ago when I had panels :-)

The lower quality panels claim 1% per year, so they'd lose around 21%
over 20 years, if the 1% rate is accurate, so maybe 25% is more accurate.

If you have a large amount of roof space then using a larger number of
lower quality, lower wattage, panels makes economic sense. The companies
that do leasing of solar systems, or that do PPAs (Power Purchase
Agreements) will usually use the lowest quality, cheapest panels.

My wife is addicted to those little solar powered garden lights: solar
cell, Ni-Cad battery, LED, sometimes a switch, and maybe five electronic
bits. So one of my hobbies is fixing them when they stop working in a
year or two. First it's cleaning and protecting battery contacts, then
bypassing the switch, then maybe replacing a bad battery, then stripping
for parts.

I've now got a drawer full of low quality solar cells. I'm going to use
them to run our whole house. ;-)

Like most houses in Thailand we have a fence, largely a concrete wall,
around our house and it is usual that there will be lights at the
gate. Unfortunately long before we bought the house the wiring to the
gate post lights "died" and rather than dig up all the wiring from the
house to the gate to repair the wiring I replaced the conventional
lights with solar powered lamps, auto on at dusk and so on.
Surprisingly they are as bright as conventional AC powered "gate
lamps" and so far they have been working for more than a year and
still going strong.
--
cheers,

John B.

On Fri, 12 Jun 2020 10:30:52 -0700, Jeff Liebermann
wrote:

On Fri, 12 Jun 2020 11:48:06 +0700, John B.
wrote:

I believe that solar panels have a "life till decreasing to some
specific output", which is why I phrased the question as I did.

Nope. The defacto standard is when the output gets to 80% of rated
power:
https://energyinformative.org/lifespan-solar-panels/

You missed the part that said, "Largely because on a sail boat
there is limited space to mount the panels"?

It's also rather difficult to aim solar panels at the sun on a moving
sailboat. So, they tend to be pointed straight up, which is not
ideal, but good enough for topping off a battery. However, I've seen
more than a few cracked panels on boats, where someone up the mast
dropped a tool or some hardware, which landed on the panel. On
sailboats, the sails often block the sun.


It must have been a rather small boat :-) I had the panels mounted
over the stern of the boat, far behind the area swept by the main boom
and 20 feet or so behind the mast. Little chance of something dropping
off the mast and hitting them.
--
cheers,

John B.

On Friday, June 12, 2020 at 6:30:56 PM UTC+1, Jeff Liebermann wrote:

It's also rather difficult to aim solar panels at the sun on a moving
sailboat. So, they tend to be pointed straight up, which is not
ideal, but good enough for topping off a battery. However, I've seen
more than a few cracked panels on boats, where someone up the mast
dropped a tool or some hardware, which landed on the panel. On
sailboats, the sails often block the sun.

Not to mention that long before you get to gimballing the solar panels, with the accompanying freezing drips down the back of your neck, you'll discover that any member of the most serious class of wind-powered sailor is a worse weight-weenie than any roadie you've ever met.

Andre Jute
I'd leave that sort of monkey business to the monkeys

On Friday, June 12, 2020 at 8:34:58 PM UTC+1, Ralph Barone wrote:

His entire setup could be reasonably reduced to an iPhone, a Bluetooth
headset and a hub generator today.

I have the hub generator and the iPhone but I don't bother with the Bluetooth headset since an iPhone app announces, in a sweetly unreasonable female voice, whatever her programmer thinks I ought to know.

Andre Jute
That setup is now nearly years old. How can everyone else have fallen so far behind?

On Friday, June 12, 2020 at 1:38:45 PM UTC-4, Jeff Liebermann wrote:
On Fri, 12 Jun 2020 13:02:10 -0400, Frank Krygowski wrote:

My wife is addicted to those little solar powered garden lights: solar
cell, Ni-Cad battery, LED, sometimes a switch, and maybe five electronic
bits.

These daze, most use NiMH batteries, not NiCd.

I just checked five batteries I salvaged from dead lights. All are NiCd.
None are NiMH.

So one of my hobbies is fixing them when they stop working in a
year or two. First it's cleaning and protecting battery contacts, then
bypassing the switch, then maybe replacing a bad battery, then stripping
for parts.

Every day, the sun charges the battery to full, and every night, the
LED discharges it until the battery is fully discharged. Neither NiCd
or NiMH can survive many such cycles. When hot, both are good for
about 500 charge cycles. When cool, about 1000 charge cycles. That
would produce a battery life of two or three years, which is what
you're seeing. Just replace the batteries and start over. They're
cheap on eBay at about $1.00/ea or sometimes less:
https://www.ebay.com/itm/113840263323

Really, it's not just the batteries. I know it's overkill due to my
overactive "fixit" gene, but I've tested things to find the failure
order I described. Batteries are down the list, below contact
corrosion and switch malfunction (which is probably also contact
corrosion). (I'm amazed they put in switches at all.)

I usually fix the contact corrosion by sanding, then smearing with
Vaseline, which seems to retard the corrosion. I fix the switches by
cutting them out and twisting the stripped wires together. The few
times I've found a bad battery, I've replaced it with one cannibalized
from a light that died of other causes.

One more rare failure mode popped up last month: Plastic rot. Something
bumped one of the lights and cracked it badly. When I pulled it up,
the plastic was so brittle it easily broke into pieces. I tell you,
Chinese junk just isn't what it used to be!

- Frank Krygowski

On Fri, 12 Jun 2020 12:58:21 -0400, Frank Krygowski wrote:

On 6/12/2020 12:05 AM, news18 wrote:

Bike content;who was that bicycle rider thaty roamed USA with solar
panels on a two wheel trailer. He had computing witha solaris system,
input by a three() key system and when has had surplus power, he could
do CB?

This guy:
https://www.cyclingabout.com/heavies...ever-behemoth/

Yep, that is the guy, althought that isn't the bike he was initially
riding, aka definitely not as loaded up. The sat link is new as is the
mac computer and various other things.

His website is probably a better place tgo find out his interests
https://microship.com.

On Fri, 12 Jun 2020 19:34:49 +0000, Ralph Barone wrote:

Frank Krygowski wrote:
On 6/12/2020 12:05 AM, news18 wrote:

Bike content;who was that bicycle rider thaty roamed USA with solar
panels on a two wheel trailer. He had computing witha solaris system,
input by a three() key system and when has had surplus power, he could
do CB?

This guy:
https://www.cyclingabout.com/heavies...ever-behemoth/



His entire setup could be reasonably reduced to an iPhone, a Bluetooth
headset and a hub generator today.

The challenge was doing it with the technology of the day and he did it,
although I think he suffered greatly from gear acculmulation sydnrome.