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  • Cooking with solar panels

    Ive been reading this:
    Cooking with solar panels: 1000 Watt of energy boils one liter of water in 6 minutes. If you want to cook with 1000 watt solar panel(s) it's still expensive. But if you insulate the chamber of the cooker you can boil a liter of water in one hour or in a day cooking 6kg of food using just a 100Wp solar panel only.
    (Peter Schwartz - Cal Poly Physics)

    He does not use an inverter nor batteries.
    My question is if i use a 1000watt cooking electric appliance, only for 30 mintues and use battery is it so that i only draw 300watt and if i use a 100Wp panel i can produce daily 300watt or more. If this is the case i dont need gas anymore cause i dont cook more than 30 minutes daily and a 100Wp system is enough.
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  • #2
    1000 Watt cooking appliance x 1/2 Hour = 500 Watt-Hour

    google ... "difference between watts and watt-hour"

    There is a difference between "power" and "energy".

    100 Watt PV Panel x 6 Hours x 80% = 500 Watt-Hour ( NET )
    Last edited by NEOH; 10-12-2017, 11:11 AM.

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    • #3
      You could benefit from learning a bit about energy and power, and how to insulate things.

      Let's see, 1,000W/6 minutes = 100 Watt hours of energy. Assuming you're at sea level atmospheric pressure:

      Even if you manage to supply all that heat without incurring any heat losses, you'll raise the temp. of 1 l of H2O by ~ 86 C. So, While in theory you might get close to a 100 C. water temp. if you start w/ H2O at ~ 14 C., you'd need to have the H2O in what would be pretty close to a perfectly insulated container to eliminate most/all heat losses. And BTW, you'd be at the boiling temp., but you'll have boiled no H2O at that point. To do that will take more energy. A lot more. Unfortunately, the near perfect insulation criteria would make any heat addition effectively impossible, creating a logical conundrum.


      Stick with gas for cooking. Better, cheaper, faster. Cooking with electricity is like cutting butter with a chain saw.

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      • #4
        I cook with an electric oven and an electric range top with solar. It just happens to be with net metered solar

        My PV systems were sized for my average load (plus some) and that included my electric range.

        I always get a chuckle when I hear someone went off grid and bought a propane range and propane refrigerator. Basically swapping the propane supplier for the power company.

        Some day when my range dies I may go with an induction cooktop or just buy one of the countertop versions. More efficient than a calrod element.

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        • #5
          Originally posted by Gerard Fivewin View Post
          Ive been reading this:
          Cooking with solar panels: 1000 Watt of energy boils one liter of water in 6 minutes. If you want to cook with 1000 watt solar panel(s) it's still expensive. But if you insulate the chamber of the cooker you can boil a liter of water in one hour or in a day cooking 6kg of food using just a 100Wp solar panel only.
          (Peter Schwartz - Cal Poly Physics)

          He does not use an inverter nor batteries.
          My question is if i use a 1000watt cooking electric appliance, only for 30 mintues and use battery is it so that i only draw 300watt and if i use a 100Wp panel i can produce daily 300watt or more. If this is the case i dont need gas anymore cause i dont cook more than 30 minutes daily and a 100Wp system is enough.
          you need to start reading physics 101 or try to cook - you'll quickly realize how flawed and impractical that 'solution' is. Is this what Cal Poly teaches nowadays or its name just being used to increase validity of the idea?

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          • #6
            About insulated cooking, here is the video of Peter Schwartz

            https://m.youtube.com/watch?v=XTQhdjVd0Fk

            Yes, i understand watt/hours. It means that in theory its possible to cook electric for 30minutes with just a 100 Wp system incl batterybank.

            Comment


            • #7
              Originally posted by Gerard Fivewin View Post
              Yes, i understand watt/hours.
              Then please explain this statement

              Originally posted by Gerard Fivewin View Post
              My question is if i use a 1000watt cooking electric appliance, only for 30 minutes and use battery is it so that i only draw 300watt
              I do not understand how you "only draw 300 watt" ?

              I say, 1000 watts x 1/2 hour = 500 watt-hours





              Comment


              • #8
                Originally posted by Gerard Fivewin View Post
                About insulated cooking, here is the video of Peter Schwartz

                https://m.youtube.com/watch?v=XTQhdjVd0Fk

                Yes, i understand watt/hours. It means that in theory its possible to cook electric for 30minutes with just a 100 Wp system incl batterybank.
                if you do then you would also understand any source of energy would do if you improve insulation - gas / coal / firewood included. Those researchers went into Uganda on public money with political agenda, not anything real. At the end I bet locals went back to their old ways so even that goal was not achieved. I think they would be more receptive if 'researchers' showed them the concept of chimney instead but that wasn't aligned with agenda I guess. What a waste ... I also understand someone probably did achieve their own goals not publicized in the video.

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                • #9
                  Or just use a well-insulated glass-covered box and reflect solar energy into it - no need for PV panels.

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                  • #10
                    Originally posted by kb58 View Post
                    Or just use a well-insulated glass-covered box and reflect solar energy into it - no need for PV panels.
                    Back in the day, I made an easily recognizable solar oven out of an inverted 20 gal. fish tank and 4 side reflectors of Al foil on fiber board. Boiled H2O etc. Even cooked some scalloped potatoes in it one time. The inside of the glass quickly fouled from steam and splatter etc. and slowed down the cooking process, but it worked well enough provided I adjusted the orientation ~~ every 20 min. or so. The spuds took most of the day to cook as I seem to recall. Proof/confirmation of concept was fun. The oven in the kitchen was faster and easier.

                    Comment


                    • #11
                      Well, the guy that posted that is a moron. I get all my hot water from PV and not like those idiots on youtube. On the entire earth, why isn't there just one person on youtube that knows how to do it? Just sticking a resistance element on PV will give you very poor performance. The Panel has to be operated at its power point. A mismatch will cause a drastic power drop. The sun, panel orientation and resistance of the heater is almost never ideal. The electronics to optimize power costs less than $10. No reason to do it the idiots way.

                      Comment


                      • #12
                        Originally posted by PNPmacnab View Post
                        Well, the guy that posted that is a moron. I get all my hot water from PV and not like those idiots on youtube. On the entire earth, why isn't there just one person on youtube that knows how to do it? Just sticking a resistance element on PV will give you very poor performance. The Panel has to be operated at its power point. A mismatch will cause a drastic power drop. The sun, panel orientation and resistance of the heater is almost never ideal. The electronics to optimize power costs less than $10. No reason to do it the idiots way.
                        I get ~ 95 % of my hot water from solar thermal. ~ 2X as efficient as PV and about as efficient as PV/heat pump combination. The u-tube poster is about like most of the rest of those folks who preach from the idiot's bible of u-tube. Seems to me that maybe some rather well developed and much more appropriate technology could be used for heating and cooking rather than PV.

                        Comment


                        • #13
                          Originally posted by PNPmacnab View Post
                          Well, the guy that posted that is a moron. I get all my hot water from PV and not like those idiots on youtube. On the entire earth, why isn't there just one person on youtube that knows how to do it? Just sticking a resistance element on PV will give you very poor performance. The Panel has to be operated at its power point. A mismatch will cause a drastic power drop. The sun, panel orientation and resistance of the heater is almost never ideal. The electronics to optimize power costs less than $10. No reason to do it the idiots way.
                          well if you look at the bigger picture he may not be so- he probably got grant for this 'research', got team of student helpers + all of them spent some time in Uganda on taxpayer's dime. The last bit I'm not sure was advantageous but some ppl pay good money for the exotic travel. At the end they all might even got some scientific recognition- printed article, gave speech etc. Trouble is this activity is very detrimental to the cause they proclaim and distorts reality in those young minds crippling them for life.

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                          • #14
                            Originally posted by max2k View Post

                            well if you look at the bigger picture he may not be so- he probably got grant for this 'research', got team of student helpers + all of them spent some time in Uganda on taxpayer's dime. The last bit I'm not sure was advantageous but some ppl pay good money for the exotic travel. At the end they all might even got some scientific recognition- printed article, gave speech etc. Trouble is this activity is very detrimental to the cause they proclaim and distorts reality in those young minds crippling them for life.
                            From what I can see, it looks like the trip to Uganda / Rwanda / Ghana was just for four students, sponsored by AidAfrica (which prominently displays a "6 brick rocket stove" on their website, with no mention of anything PV).
                            CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

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                            • #15
                              Originally posted by NEOH View Post

                              Then please explain this statement

                              I do not understand how you "only draw 300 watt" ?

                              I say, 1000 watts x 1/2 hour = 500 watt-hours
                              Typing error miscalculation and wrong terminology.

                              In a tropical country i perhaps can produce 500Wh with a 100-120Wp daily. My intention is to cook 30 minutes daily with a 1000watt electric stove. If i setup a100-120Wp system with an agm battery 100-200Ah i can achieve my goal OR NOT? That was my initial question.
                              Last edited by Gerard Fivewin; 10-13-2017, 02:16 AM.

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