30 W Solar panel - can it charge a generator?

Sat Jan 28, 2012 7:28 pm   

I am thinking green here. I have recently seen a couple of 15W solar
panels (15 X 2) on sale at Canadian Tire for $99.00. If I have those
hooked up to an electric generator, could I :

1) Trickle charge the generator
2) Have enough power to run some lamps, computers etc

Any suggestions would be great. Thanks

Sat Jan 28, 2012 7:28 pm   

daviddschool <daviddschool_at_gmail.com> wrote in news:e35a378a-671d-473e-
8af8-93cca7d39f81_at_eb6g2000vbb.googlegroups.com:


1:no.(you cannot charge a generator, you might try a battery)
2:no.

Sat Jan 28, 2012 7:40 pm   

On Jan 28, 12:31 pm, Sjouke Burry <s_at_b> wrote:

Ok, how about this:
http://www.canadiantire.ca/AST/browse/Green/EnergyConservation/RenewableEnergy/PRD~0111879P/12V+Eliminator+Renewable+Energy+Deep+Cycle+Battery.jsp?locale=en
This is a battery like you suggested. Could this be trickled charged
to run things constantly?
And thank you for the quick reply

Sat Jan 28, 2012 8:53 pm   

On 1/28/2012 11:28 AM, daviddschool wrote:

You need to do a little detective work.

How many watts does the lamp in your bedroom use?
How many watts does your computer use?
How many hours per day can you get 30 watts from your solar panels?
If you put 30 watts for one hour into a battery how many watts will come
out? Hint; It won't be 30.
What is the efficiency of converting 12 volts dc to 120 volts ac?

After you have some idea about the answers to these questions.you can
answer your own questions.

Mikek

Sat Jan 28, 2012 9:32 pm   

On 1/28/2012 9:40 AM, daviddschool wrote:

I don't know a lot about batteries for renewable energy, but that
battery looks
suspicious.
First it's $300. You need to find a better battery source.
It's rated at 1 amp for 100 hours. Typically, batteries are specified
for 20
hour discharge. I'd look at the curves before buying one.

You shouldn't have to pay $3/watt for solar panels.

Don't buy solar stuff from a tire store.

Do some math. Add up all the loads you want to run for how long
and calculate the total number of amp hours per day at 12V.

You need at least that much solar power accumulated per day.
Problem is that solar panels are rated for power output at noon
on a sunny summer day in the lower latitudes.

Do some googling and you'll find maps of average insolation history at
various locations.

You'll find that, for most of us, The total solar power you're gonna
get to charge your batteries on a cloudy winter day approaches zero.

You need a LOT bigger array and a lot more batteries than you might
think to do anything useful. Typically, you want more power when the
sun ain't shining.

Bottom line is that solar power is not even close to cost effective,
or green, for most of us.

I can think of two cases where solar power is beneficial to the end user...
1) where power is not available at all or costs way too much to acquire.
If you have a traffic sign with lights on it, the cost of the solar array
and batteries is often WAY less than the cost to dig up a street to
route power from a source right across the street 100 feet away.
2) where you can get someone else to pay for it...government subsidies.
For the record, I'm NOT interested in paying for YOUR solar system.

It makes almost no sense to pay $100 for panels and $300 for a battery
plus another $$ for the inverter to get, maybe 50 watt hours on a winter
day. This assumes that you're in Canada and not Arizona.

Even if your system is 100% efficient and you lived in a place that
was never cloudy, you're gonna get a couple of hundred watt hours/day.

You're gonna be into this sytem $4-500 by the time you buy the wire
and brackets and inverter and connectors and nuts and bolts and ....
If you save 2.5 cents/day in electricity, the payback period is
50000/2.5 is over 50 years. If you count the cost of investing the
money, the payback is...never. And that assumes your battery lasts
50 years.

Stated another way, the carbon footprint of you driving to two stores to
pick up the battery and panels is probably bigger than all the carbon
you'll ever save by using them. And that ignores all the carbon
costs of making the stuff in the first place, shipping it around the world
and disposing of it when it's done.

To recap.
Not cost effective.
Not green.

Are we green yet?

Sat Jan 28, 2012 10:52 pm   

On Jan 28, 2:53 pm, amdx <a...@knologynotthis.net> wrote:

So my question is why would anyone buy a solar panel then to run a
battery inverter?

Sat Jan 28, 2012 11:31 pm   

On Jan 28, 12:52 pm, daviddschool <daviddsch...@gmail.com> wrote:

As stated above, in places where the alternatives are more costly and/
or less 'green' than setting up an effective solar system. You suggest
that you have a generator and they can be cost effective, but are
certainly not 'green'. A micro hydro plant would likely be more costly
but can be exceedingly 'green'.

Neil S.

Sat Jan 28, 2012 11:35 pm   

On 1/28/2012 1:31 PM, nesesu wrote:

the state. May be true in other states, as well.

Paul

Sun Jan 29, 2012 1:57 am   

On 1/29/2012 4:52 AM, daviddschool wrote:


Putting aside all the tech stuff and the well made point of the cost at
the tire joint, if you run your stuff on 12v (LED lamps and use a
computer that will operate off 12v) it can be done and plenty of people
are doing that. It will however take an initial capital outlay of more
than the $99 level :-)

Cheers ....... Rheilly P

Sun Jan 29, 2012 3:19 am   

On 1/28/2012 2:52 PM, daviddschool wrote:

That's obvious, but I'll say it anyway, the device they are
using is designed for 120 volts ac input.
Hmm...
maybe you mean the whole concept of solar panels for household use.
If we were starting from scratch, efficiency would be a very important
criteria. Our devices would be designed to run on DC and would probably
use a voltage higher than 12 volts to reduce I^2R losses in the
household wiring. We would also be very stingy with what is on and
for how long.
Mikek

Sun Jan 29, 2012 6:28 pm   

On Jan 28, 9:19 pm, amdx <a...@knologynotthis.net> wrote:

Thank you everyone for the breakdown. I really appreciate it. So, if
Canadian Tire isn't the place to get it, how about a starter kit for
myself where I can work up to a more feasible solution? Any
suggestions? Any manufacturers? Any websites? I know I am not going
to be turning my entire house into a solar mecca, but I would like to
start.

Thu Feb 02, 2012 2:55 am   

daviddschool <daviddschool_at_gmail.com> wrote in
news:accc0f63-485c-4a04-9f32-7034301dc79c_at_b18g2000vbz.googlegroups.com:


The problem with a solar panel of of any power is,
that on a normal day you are lucjy to get 30% of
the specification, wich is very optimistic, and is
not even reached for high noon desert sun.
That leaves you about 5 wats per panel, and you sure need
a lot of panels to reach any usable power.
Storing that is no problem, but soring only imroves, what
peak power you can draw.
Example:
5 watts in ~12 hours is 60 watthours.
Withdrawing it leaves you with about 80% efficiency, or ~50WH.
Using a 100 watt device will drain the batteries in 30 minutes.
To be usefull at all, you need big panels.
A neigbour of mine, in high summer and 30 square meters of panels,
gets peak 1700 Watts, and about a mean of 800 watts during 12 hours
on a sunny summer day.
Now in winter it gives about 200-400 W during about 7 hours.
That kind of equipment might give a household a usefull daily ration
of power, provided bad weather stays away.
He has a 600 volts converter, and feeds it back into the
240 volt household power.
You can sometimes see his meter running in reverse, but most of the
time he can directly use the power.(He runs a gas station, and the pumps
and computers run(almost) for free).
Location:Netherlands, not a very sunny country, about like England.
Batteries are only advisable, where normal power is not available.
Good batteries are VERY EXPENSIVE. Dont use the China ones.
And get a computer controlled charge unit, or even the expensive
batteries give up the ghost in short order.
For batteries:DO NOT OVERCHARGE, and , DO NOT TRICKLE CHARGE, and
DO NOT DEEP DISCHARGE.
Those three things kill batteries quickly. Or:
Stop charging when they are almost full(~14.8 volts for AGM).
Stop drawing power when almost empty(~10-11 volts).
I hope this info is useful.

Thu Feb 02, 2012 11:42 am   

On 02/02/2012 01:55, Sjouke Burry wrote:


In the UK, the government have been scammed into paying well-off
householders handsome amounts if they drive their meters backwards with
their expensive and over the top solar PV arrays. Meanwhile other
residents have to pay higher energy bills to make up for the shortfall.

--
Adrian C

Thu Feb 02, 2012 1:04 pm   

On 2012-02-02 11:42:02 +0100, Adrian C <email_at_here.invalid> said:


same here in france ... I pay for the neighbour's pv panels ...

--
----------
Kripton

the ESR Repository @ http://kripton2035.free.fr/esr-repository.html
the Geiger Repository @ http://kripton2035.free.fr/geiger-repositor.html

Thu Feb 02, 2012 1:59 pm   

On 2/2/2012 4:42 AM, Adrian C wrote:

Is that to suggest that government would take taxpayers hard earned
money and spend it in wasteful way?
Mikek