Upgrading questions...

Re: Upgrading questions...

With a 130 watts of solar panel--you are right at the low end of charging your battery...

130 watt / 17 volt = 7.6 amps or so...

130 AH * 50% / 7.6 amps = 8.6 hours or, roughly two summer days to recharge from 50% use...

If this meets your needs--great... If you plan on using and recharging at the same time--your battery may be sitting below ~75% state of charge longer than wanted... May cause your battery to die sooner.

-Bill

Re: Upgrading questions...

Sort of depends on what you want to do... Roughly, you would want round 5% to 13% of the battery AH capacity as charging current...

180AH * 5-13% is = 9 amps to 23.4 amps...

Or *~16 volts (Vmp) = 144 Watts to 374 Watts of solar panels...

For a deep cycle battery, it would be better to be in the 10%-13% range because you need to have enough current to vigorously "boil" the battery to mix the electrolyte during equalization...

AGM's don't need (and should not have) equalization, plus AGM's have lower self discharge--so they can work fine nearer to the 5% range. But AGM's can also accept higher charge currents and can work well above the 13%+ charging current range (as always, check the specs. for your batteries).

Ideally, you probably want to size the solar panels for the amount of power you need to use--And size the battery for 6x daily AH/WH load (3 days of no sun, max 50% discharge for longer cycle life)...

Without knowing your daily load requirements, what seasons you want to use the system, and such... we are just guessing.

Using a kill-a-watt meter and this website, you can better size the system to your needs.

Working backwards, lets say you are in Montreal Canada, 130 watts of panels, fixed mounting at latitude, and using 0.52 as the derating factor (flooded cell batteries, AC inverter).

From the second link we find that a 1kW (have to use 1kW as this is the minimum value accepted) set of solar panels will generate:

Results
Solar Radiation
:Month
:Solar Hours per day
:kWhrs per month
:$Canadian worth of electricity per month

1      3.24          55     4.74 
2      4.02          62     5.34 
3      4.40          72     6.21 
4      4.61          67     5.78 
5      4.77          69     5.95 
6      5.12          70     6.03 
7      5.62          78     6.72 
8      4.76          66     5.69 
9      4.92          69     5.95 
10      3.66          55     4.74 
11      2.01          29     2.50 
12      2.10          34     2.93 
Year   4.10          726     $62.58

If we multiply by 130 Watts/1,000wperkW (I will use Excel):

:Month
:ave Hours of Sun
:ave kWhrs per month
:ave kWhrs per day

1    3.24   7.15   0.238       
2    4.02   8.06   0.269       
3    4.40   9.36   0.312       
4    4.61   8.71   0.290       
5    4.77   8.97   0.299       
6    5.12   9.10   0.303       
7    5.62   10.14   0.338       
8    4.76   8.58   0.286       
9    4.92   8.97   0.299       
10   3.66   7.15   0.238       
11   2.01   3.77   0.126       
12   2.10   4.42   0.147  
==============================     
Year ave sun=4.10   94.38kWhrs per year

So--The Fourth column above sows that you can get 200 to 300 Watt*Hours per day for 10 months of the year...

If you get snow--you can tilt the array to 90 degrees (vertical) and shed snow better during winter.

So--as you can see, there is not a lot of power from a 130 watt solar panel... So, you have to know your loads well, and, if you use more power than the panels can generate (say during the winter), you will need a back up power source (generator--if off grid).

-Bill