Small PV System for remote use

 Need a small amout of power at a remote site.  Approximately 800 watt
hours per week only in the summer.  Approximately 300 watt hours on
Saturday and another 300 on Sunday.  Less than 1A max current at
120VAC.  Almost all of the power usage will be mid day.  Economics is an
issue, I'd like some recommendations on a PV panel, charge controller,
12V battery.  I was planning on using a cheap inverter, as the usage is
for low current motors.

How about this charge controller:
http://www.solar-electric.com/ss-10.html

A 12VDC deep cycle battery from Walmart can be picked up on sale for
under $60.

Phil

  Hi Phil,

Those Morningstar SunSaver pwm charge controllers supposedly work very well,
according to one cabin
owner I know who has one.  I have to upgrade my cheapie charge controller soon
and i'm eyeing one of
those myself.  I'd prefer an MPPT charge controller but I don't quite have a big
enough system to
reap its benefits nor can I quite afford one just yet.  But one suggestion is to
go up a model and
get one with the low voltage disconnect.  That added feature helps preserve the
life expectancy of
your batteries by preventing them from being discharged too far.  An automatic
charge equalization
feature is another good thing to have, but of course it depends on how much you
want to spend and
how important it is to you to have a well maintained battery bank.  I think the
term is Risk/Reward
Return.

Since price is your main factor, I would start with a single 75 watt PV (you
might find it cheaper
to buy two 50 watt PV's), the charge controller you were looking at with the LVD
feature, and a
couple of 12 volt sealed AGM type batteries of at least 100 AHr @ 100 hr ratings
wired in parallel.
This way your batteries are being charged up thru the week, and you should have
enough to carry you
thru a weekend in case there isn't enough sun on the weekend to replenish your
battery bank.

This should get you started, but the beauty of PV is that it's totally modular.
You can always add
more PV's and/or batteries as you need them.

Personally i'd go for 6 volt deep cycle batteries (would have to do a price
comparison vs 12 volt
sealed) because they generally have more capacity in them and I don't mind
checking their fluid
levels periodically.

I hope this helped.  Good luck with your future system.  It's a good investment.

PS.  At one time Siemens Solar used to make Cottage Kits of various sizes.  A
nice box containing a
PV('s), pwm charge controller, PV mount, and some wire, all you needed was a
battery.

 wrote:


SYSTEM SIZING                             SYS. VOLTS       BATT. V
PHOTO VOLTAIC                                12             12
240 VOLT WATT HOURS PER DAY                   800          W HOURS
INVERTER EFFICIENCY                          0.9  
ACCOUNT FOR INVERTER INEFFIENCY               888.88       W HOURS
12 VOLT WATT HOURS PER DAY                   0             W HOURS
SYSETM VOLTAGE                               12            VOLTS
TOTAL Ah DEMAND PER DAY 74.07   A HOURS
BATTERY SIZING    
NUMBER OF DAYS AUTONOMY                      5  
MAX. ALLOWABLE DEPTH OF DISCHARGE             0.7  
BATTERY CAPACITY                             529.10         A HOURS
LOWEST 24 Hr AVERAGE TEMPERATURE                5           DEGREES
TEMPERATURE CORRECTION FACTOR                0.88  
ADJ. BATTERY CAPACITY                        601.25         A HOURS
SELECTED BATTERY    
SELECTED BATTERY DISCHARGE RATE              120            HOURS
Ah CAPACITY SELECTED BATTERY                 600            A HOURS
NUMBER OF BATTERIES IN PARALLEL              1  
NUMBER OF BATTERIES IN SERIES                1  
CAPACITY BATT. BANK 120 Hr RATE               600            A HOURS
DAILY DEPTH OF DISCHARGE                     12.34          %
SUITABILTY OF SELECTED BATTERIES             YES            YES/NO
PHOTOVOLTAIC ARRAY SIZING    
DESIGN TILT                                  60             DEGREES
DESIGN MONTH   JUNE  
TOTAL ENERGY DEMAND PER DAY                  74.07          A HOURS
BATTERY EFFICIENCY                            0.9  
ARRAY OUTPUT REQUIRED PER DAY                82.304          A HOURS
PEAK SUN HOURS FOR TILT/MONTH                4.5  
SELECTED MODULE      
SELECTED MODULE I AT 14 V NOCT               4.5            AMPS
SELECTED MODULE NOMINAL VOLTAGE              12             VOLTS
GUARANTEED CURRENT                           4.05           AMPS
NUMBER OF MODULES IN SERIES                  1              MODULES
OUTPUT PER MODULE                            18.22          A HOURS
NUMBER OF PARALLEL STRINGS                   4.51           STRINGS

This will not match exactly but should give you some idea of what you
are looking at.

Days of autonomy is set at five in this example and may be increased or
decreased as conditions warrant.

George

 George
 I am a little confused, if my max draw is 300 watts per day, why do I need so
much capacity?

Thanks,
 Phil

George Ghio wrote:

 You don't. You just met "The Solar Consultant" .....


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