Solar generator

[Rugsnfeathers]

I just purchased a 600 watt solar generator.  What size solar panel should I buy - 100 Watts, 200 Watts or in between?  I plan on using the solar panels for the 600 Watt solar generator and a 12V battery bank (future build).

[andersonjk4]

I'm designing an off-grid solar power system for my new home right now.  The panel sizing question comes down to how fast you want to recharge your batterie(s) and how much you are using those batteries while they are charging. 

If you are going to use the 600w generator very intermittenly; like use it for a day or night and then let it sit for many days to recharge, then a 100W panel would be plenty big.  If you want to be using it and recharging it daily then I might step up to a 200W setup. 

For example I installed a new system in our camp trailer earlier this year (2 - 100Ah 12V batteries [2400Watts] and 4 - 100W panels).  Under pretty heavy usage (drip coffee in in the morning, radio all day, kids watching TV for a few hours, furnace fan at night) over a week of camping I have still needed to run a small generator to add some extra charge. We could be a little more frugal with power and make it through on solar alone if the sun conditions are good. 

If your usage is pretty light and you are able to have optimal panel placement I would say a single 100W panel is probably good.  If your usage will be heavy I would consider going to a few panels (or maximizing the generator input). 
 

[Rugsnfeathers]

I'm designing an off-grid solar power system for my new home right now.  The panel sizing question comes down to how fast you want to recharge your batterie(s) and how much you are using those batteries while they are charging. 

If you are going to use the 600w generator very intermittenly; like use it for a day or night and then let it sit for many days to recharge, then a 100W panel would be plenty big.  If you want to be using it and recharging it daily then I might step up to a 200W setup. 

For example I installed a new system in our camp trailer earlier this year (2 - 100Ah 12V batteries [2400Watts] and 4 - 100W panels).  Under pretty heavy usage (drip coffee in in the morning, radio all day, kids watching TV for a few hours, furnace fan at night) over a week of camping I have still needed to run a small generator to add some extra charge. We could be a little more frugal with power and make it through on solar alone if the sun conditions are good. 

If your usage is pretty light and you are able to have optimal panel placement I would say a single 100W panel is probably good.  If your usage will be heavy I would consider going to a few panels (or maximizing the generator input). 
 

Thank you very much for your reply.  Pretty much sums up of what I intended to use it for.  I have a generator too, and one of the reasons i like to use it for is mainly using it to power a Chinese diesel heater for either my tent trailer or hard top trailer at night when boondocking, or even my Kodiak 10 x 10 tent cause I can just put the 3 inch hose through the stove jack which I installed on the side wall.   Otherwise, like you, I have the option to use the gas powered generator when I need the extra juice for other electronics.  Again, thanks for the educational advise. 

[CP]

You need to look at your SG’s specs as to DC input voltage and power and match the panel (or panels to that). 

[MR5x5]

You need to add up your loads in terms of Amp-hrs or Watt-Hrs and size accordingly from there.  Your diesel heater (5kW?) requires ~10A during the glow plug cycle - once operating it will take anywhere from 1 to 3 amps depending on temp setting.  Little LED lights are like 0.75A per, a basic 12V fridge is on the order of 3-4A and so on... My little setup consumes about 25 Amp-hrs per day on average.  I run a 175W panel and in the summer break about even.  That said I am usually in the woods with limited sun windows.  Late fall in the Palouse chasing roosters I'm not able to keep up - but over the course of a few days I do fine with a 100 A-hr battery.

Figure a solar panel is about 60% efficient, i.e. 60W output for a 100W panel for typical sunny day NW charging,  So Pwr = W = VI would tell you typical charging amps will be on the order of 4 amps for a 100W panel (charging voltage is nominally 14V).  A lot depends on how well your panel can see the sun.  If you're in trees you are only going to get maybe 4 hrs of good sun a day - wide open sky maybe 8. So that is 16-32 Amp-hrs per day from a 100W panel. For cloudy days cut everything by 80%. In winter I'd cut it by 95%.  Personally I would not go with a 100W.  I'd say 175W or 200W minimum.

Good luck with it.

[KFhunter]

If you want 100w get a 200w panel

I’ve never seen a true 100w output from a 100w panel, best I can usually get is 80-85 during optimal conditions (high noon sun, clean panel, perfectly adjusted)

Most of the time the panel is running about half of its rating

Basically double the desired input with panels

[andersonjk4]

If you want 100w get a 200w panel

I’ve never seen a true 100w output from a 100w panel, best I can usually get is 80-85 during optimal conditions (high noon sun, clean panel, perfectly adjusted)

Most of the time the panel is running about half of its rating

Basically double the desired input with panels

 

[MR5x5]

FWIW - Panel rating is for the Equator under clear skies at noon on Equinox.  No BS.  Makes sense if you think about it.