Re: How much energy from solar panels can you really use?

On 03/02/12 5:06 AM, Pete S wrote:
> This question is for those who store their solar panel energy in batteries.
>
> "How efficient is a modern battery storage system in storing solar power for
> later use?"
>
> I have heard that using batteries for storing electricity is about 25% efficient.
> That is: If you charge your battery bank at the rate of one kilawatt hour/hr of
> energy into the battery bank, only about 25% or 250 watt hours, is actually
> useable due to heat losses, chemical reactions, or whatever.

I can charge a battery bank with only a 10W charger, but it would take some time
to be fully charged. Don't confuse the _capacity_ to charge a system with the
_ability_ to charge a system

> Maybe they meant the the whole making/storing process, including losses from an
> engine/generation system is what's only 25% efficient? I don't know for sure and
> that is why I am asking.

The efficiency is the percentage of the power required to generate energy to the
actual power that eventually can be used (the solar array). It has nothing to do
with what the output is connected to (the batteries). More below
>
> An example of one way to answer would be as follows:
>
> -On a given day , a solar array produces 5KW of electrical energy and it is all
> sent to the battery bank, but no power is taken from that battery bank during
> the test.

The solar array _PRODUCES_ 5KW, and that has nothing to do with how much energy
is required to charge the batteries. That may only be a few hundred watts or
less, or whatever it takes to fully charge the batteries. Unless you use that
power elsewhere, it is wasted power

In fact, depending on the charge current required, it's more efficient to use a
100 watt generator (providing the voltage is more than the battery voltage, and
current controlled). Using a generator with the capacity to supply 40-50 Amps
(110V, 5 Kilowatts) could damage the batteries, when all the batteries need is a
(controlled) trickle charge of a few amps

> -Once the sun goes down, read the specific gravity of the electrolyte in the
> battery bank and then apply a reasonable load to it.

Fine - good thinking

> -Continue to take and measure power being extracted from the battery bank until
> the specific gravity of the battery bank is back to the same reading as it was
> when loading began.

OK

> -Read the power consumption meter to obtain the total power that was drained
> from the battery bank during the test.

er... here you take a WRONG turn

> -Divide output power by input power to determine the efficiency of the
> storage/power recovery system.

Dividing the CAPACITY to provide power, by the power generated by the batteries,
in no way reflects the efficiency, as the capacity might not be used to it's
fullest extent to charge the batteries.

What if you've got the array hooked up to your house as well, and while those
batteries are being charged, you've turned on the oven for 15 minutes, had the
TV running, put your laptop charger on, used an electric drill for a few seconds.

the solar array has the _capacity_ to supply all that power, but when it's not
used, it's just not being used!!! It's wasted!!

A good analogy is your water supply. If you want a bath, it takes 3 minutes to
fill to the level you want. Go turn on every other tap in your house. It will
STILL take five minutes to fill the bath to that level. The _capacity_ to supply
the water far exceeds the ability to drain it from one tap or several taps.

>
> If there's a better way to measure the efficiency, I'm wide open to it.

Though not impossible, doing it this way is not a way to estimate the efficiency.

Mho has a good point about supplying 1KW and then using 2KW. Think about it
>
Graham

> Pete Stanaitis
> ---------------
>
>
>

<snip>

sorry, my date/time was out. (been fixing a program that stuffs up at midnight)

Graham

It's just a reminder that we throw terms around carelessly, sometimes, and
sometimes people throw tech terms around and have no idea what they are
talking about.

Funny we never use mph (or kph) for a distance we travel to somebody's house
or miles (or km.) for how fast our car is travelling. This confusion is used
frequently for scammers and techies being careless. We forgive the
latter...LOL


-------
"argusy" wrote in message news:(E-Mail Removed)...

Mho has a good point about supplying 1KW and then using 2KW. Think about it


Graham

"Mho" <(E-Mail Removed)> wrote in message
news:VZTYq.12111$(E-Mail Removed)...
> It's just a reminder that we throw terms around carelessly, sometimes, and
> sometimes people throw tech terms around and have no idea what they are
> talking about.
>
> Funny we never use mph (or kph) for a distance we travel to somebody's
> house or miles (or km.) for how fast our car is travelling. This confusion
> is used frequently for scammers and techies being careless. We forgive the
> latter...LOL
>

The ones that tickle me are those that think of a batter as a similar device
as a bank account. No clue how you can put 1KW in and take 2KW out.

On 10/02/12 6:14 AM, NotMe wrote:
> "Mho"<(E-Mail Removed)> wrote in message
> news:VZTYq.12111$(E-Mail Removed)...
>> It's just a reminder that we throw terms around carelessly, sometimes, and
>> sometimes people throw tech terms around and have no idea what they are
>> talking about.

Electronics techs (like me) have an annoying habit of shortening power usage
(per time) to just power. We know what we mean, even when we're discussing both
terms, and understand the difference when we use the same terms to mean two
different concepts. I had a devil of a time convincing a secretary how a 1.5 Kw
rated solar array can supply 9Kw during a day of decent sunshine. Yep. She's blonde!
>>
>> Funny we never use mph (or kph) for a distance we travel to somebody's
>> house or miles (or km.) for how fast our car is travelling. This confusion
>> is used frequently for scammers and techies being careless. We forgive the
>> latter...LOL
>>
>
> The ones that tickle me are those that think of a batter as a similar device
> as a bank account. No clue how you can put 1KW in and take 2KW out.
>
That had me going for a second or two - "batter"
oh.... missing a "y", then it made sense.

Yeah - and everybody has a credit account. Not many say they have a debit
account, or realise what the difference is.

NotMe wrote:
> "Mho" <(E-Mail Removed)> wrote in message
> news:VZTYq.12111$(E-Mail Removed)...
>> It's just a reminder that we throw terms around carelessly,
>> sometimes, and sometimes people throw tech terms around and have no
>> idea what they are talking about.
>>
>> Funny we never use mph (or kph) for a distance we travel to
>> somebody's house or miles (or km.) for how fast our car is
>> travelling. This confusion is used frequently for scammers and
>> techies being careless. We forgive the latter...LOL
>>
>
> The ones that tickle me are those that think of a batter as a similar
> device as a bank account. No clue how you can put 1KW in and take
> 2KW out.

That's simple. You put enough in in previous days to make up the difference.

Mostly off-topic here but....

My favourite is the "A pessimist states, 'The cup is half full', while an
optimist states, 'The cup is half empty'".
Most people jump to contradict to which the response would be "I was trying
to empty the cup"

Another one I like is "clockwise" which depends on your point of view. A
shaft from the other end is turning counter-clockwise...or for the other
half of the world anti-clockwise. I am always quick to add "looking from the
top to clockwise instructions at the table". Most don't get it. LOL


So many things are relative...right cous.?


--------
"argusy" wrote in message news:(E-Mail Removed)...

On 10/02/12 6:14 AM, NotMe wrote:
> "Mho"<(E-Mail Removed)> wrote in message
> news:VZTYq.12111$(E-Mail Removed)...
>> It's just a reminder that we throw terms around carelessly, sometimes,
>> and
>> sometimes people throw tech terms around and have no idea what they are
>> talking about.

Electronics techs (like me) have an annoying habit of shortening power usage
(per time) to just power. We know what we mean, even when we're discussing
both
terms, and understand the difference when we use the same terms to mean two
different concepts. I had a devil of a time convincing a secretary how a 1.5
Kw
rated solar array can supply 9Kw during a day of decent sunshine. Yep. She's
blonde!
>>
>> Funny we never use mph (or kph) for a distance we travel to somebody's
>> house or miles (or km.) for how fast our car is travelling. This
>> confusion
>> is used frequently for scammers and techies being careless. We forgive
>> the
>> latter...LOL
>>
>
> The ones that tickle me are those that think of a batter as a similar
> device
> as a bank account. No clue how you can put 1KW in and take 2KW out.
>
That had me going for a second or two - "batter"
oh.... missing a "y", then it made sense.

Yeah - and everybody has a credit account. Not many say they have a debit
account, or realise what the difference is.

Have we wandering into deep frying now?

LOL

-------------
"NotMe" wrote in message news:jh17qt$6k7$(E-Mail Removed)...
The ones that tickle me are those that think of a batter as a similar device
as a bank account. No clue how you can put 1KW in and take 2KW out.

"Mho" <(E-Mail Removed)> wrote in message
news:OgeZq.9793$(E-Mail Removed)...
> Have we wandering into deep frying now?
>
> LOL
>
> -------------
> "NotMe" wrote in message news:jh17qt$6k7$(E-Mail Removed)...
> The ones that tickle me are those that think of a batter as a similar
> device
> as a bank account. No clue how you can put 1KW in and take 2KW out.
>
I have vision problems and proof reading is not currently my strong suit.

Not complaining as the alternative is much less pleasant.

LOL. I did enjoy the typo though.
Please do not be offended. Most of us do it.

-----------
"NotMe" wrote in message news:jh9anb$gvt$(E-Mail Removed)...

I have vision problems and proof reading is not currently my strong suit.

Not complaining as the alternative is much less pleasant.