Sizing a Solar Panel Battery Charger

Quinn

Hi I’m new to this forum and have question I’m hoping someone much smarter than I can answer.  I’m looking at purchasing a new type of portable stove that uses a small amount of electricity for off the grid use. The manufacturer told me the smallest battery they recommend is a 12VDC 35AH. A fully charged battery I am told will provide for 2-3    1-1/2 hr uses before it will need to be charged.

The question is what size solar panel will I need to buy to re-charge the battery in a decent amount of time?  The electricity it uses is 100w / 20min pre heat and 100w / 30sec for ignition. Then it uses 15W continuously to run a small blower and fuel pump for however long you want to cook or heat which for me I figure 1-1/2 hrs. Per time.

So it’s 100W for 21min then 15w for 1-1/2 hrs two times per day from a 12vdc 35ah battery.  Sorry if it’s confusing but I’m trying and if anyone can help it will be great. Thx

mike74820

i would say at least 200 watts of solar panels and a minimum 10 amp charge controller 

just starting

What type of stove is this ?

mike95490

Please, tell us more about this magic stove.  I know of one propane stove than uses just a 9V battery for the spark ignition,

Quinn

Thanks for the info mike74820 I will look into it ASAP. Hopefully a 200w portable solar panel system is available if not I will make do and thinking of hooking it up to a small Lithium Fe battery. Any idea on how long a 200w panel will take to re-charge the battery? I will also be able to use the battery / solar outfit for some Led lighting and a Ham Radio.  Gatt Energy is the company that makes the stove www.gattenergy.com should get you there. If if works as advertised it's pretty neat no propane or liquid fuel it uses wax. I figure if and when the SHTF a stack of wax will be cheaper and easier to keep around than propane tanks and disgusting kerosene.      

mike74820

how long it takes cant really be said until you know how many amp's you are using in a day. but to give you and example if you use 20 amp's in a day that,  The 10 amp controller will give back the 20 amps in about 3 hours in good sun

Quinn

Thanks again Mike. One more question and I promise to leave you alone. To help me understand usage:
 If it's lets say (2) x 100w for 30 min = 100w hour    and   (2) x 15w for 1-1/2 hours = 45w hour
Add them together  100w hr + 45w hr = 145w usage for the day   or   145w / 12vdc = 12amp. Is that how it works or am I way off?

mike95490

Watts consumed x Time ( hours )  = watt hours consumed  ( say 250 Wh consumed)
Harvest, you can expect about 80% of the PV panel nameplate.  100w panel can be expected to produce 80W under ideal conditions. 250Wh  @ 80W would need nearly 4 hours of perfectly aligned sun.