300w Solar Panel
So I have a 15W Solar Panel, 750W power converter, 300W rice cooker, and a 12V battery…?
How many watts would be the total if they were all combined?
You’re thinking of running the rice cooker from the solar panel? I’m afraid the news is pretty much all bad.
Assuming everything was 100% efficient (after the solar panel’s 15W rating), you would need 20 hours of best sun conditions to get enough energy to charge the battery to run the rice cooker for one hour.
In practice you’ll need at least twice that because you can’t use the last few WH in a battery charge, so figure 40 hours.
Battery charge and discharge are not 100% efficient and neither is the inverter. These losses will push you to at least 50 hours.
“Best sun conditions” means high noon on a clear blue summer day in the southwest US, or similar. A typical summer day gives the equivalent of maybe seven hours of “best sun conditions” as the sun is only directly overhead for a short time, and even if you aim the panel at the sun the light loses strength at other times because it has to travel through more air. So we’re looking at seven days of charging for an hour of cooking.
If a winter day with no clouds, you only get the equivalent of about five or six hours of those “best sun” conditions per day… now you’re up to ten days charging per cooking hour.
If the weather is cloudy, more charging time is needed. If you move north, again, more charging time is needed.