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Solar panels

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  • bob storrar
    blockquote, div.yahoo_quoted { margin-left: 0 !important; border-left:1px #715FFA solid !important; padding-left:1ex !important; background-color:white
    Message 1 of 6 , Nov 16
      I have a portable 12v cooler that draws 50 watts or 4 amps. Has anyone tried to use a solar panel to power a 12v cooler all day? Like when you are at anchor  and you will be gone all day.

      Will an overcast day have a significant effect on the output of the solar panel?  Do I need a voltage regulator of some kind?  Should I run the solar panel wires to the house battery and draw of the that?


       Is there any reason  that I can't plug the panel directly to the cooler and walk away for the day?

      Thanks in advance for your input
      Bob
      Moon Dance #177


      Sent from Yahoo Mail for iPhone
    • Cecilia Potts
      Never directly connect solar panels to a 12 V battery, damage will occur. I work for a solar company that specializes in portable power solutions for defense
      Message 2 of 6 , Nov 17
        Never directly connect solar panels to a 12 V battery, damage will occur. I work for a solar company that specializes in portable power solutions for defense and cruising sailboats. 

        Some panels have solar charge regulators built in, but those are usually the mA variety or lower voltage.

        Pick up a BlueSky Solar charge controller ~$180. These are MPPT (maximum power point tracking) and for your and many other applications, far superior to their PWM cousins.

        Overcast and any shading will significantly impact your panel output. Panels are rated using STC which is standard testing conditions at 77 degrees F and a specific atmosphere. (Haven't had enough coffee yet to remember). You can determine very precise amounts of maximum irradiance at NREL.com for your location, but for spitball estimation, we use 5 hours of solar for anything in the Southern US and 4 hours for our friends in the Northern tier. 

        So, for your draw using the V x A = W math...which assumes 100 percent efficiency (and nothing is 100 efficient) ....and based on 8 hours of cooler run time...your draw is 32 Ah to run cooler.. A 100 W, 12 W panel will provide ~8.3 A per hour. Using 5 hours of direct sun that's ~41 Ah of power gen. Used in concert with an MPPT solar charge controller, that should be adequate to support the load and even put a little more in the bank. Just a numbers game. Important, too to balance solar with battery bank size so you don't over/under cycle batteries, but that's another post for another time.

        You can email me directly at work if you or anyone has any more questions cpotts@...
        I'm happy to help!!! 
        You all have helped me a lot so far on other things

        Ceal #13 s/v Wooden Shoe

        On Nov 16, 2017, at 11:57 PM, bob storrar bobst9234@... [catalina28] <catalina28@yahoogroups.com> wrote:

         

        I have a portable 12v cooler that draws 50 watts or 4 amps. Has anyone tried to use a solar panel to power a 12v cooler all day? Like when you are at anchor  and you will be gone all day.

        Will an overcast day have a significant effect on the output of the solar panel?  Do I need a voltage regulator of some kind?  Should I run the solar panel wires to the house battery and draw of the that?


         Is there any reason  that I can't plug the panel directly to the cooler and walk away for the day?

        Thanks in advance for your input
        Bob
        Moon Dance #177


        Sent from Yahoo Mail for iPhone

      • dfokdfok
        Last season I had two 50 watt panels running through a Morningstar Duo (pwm) controller. At the top of the Chesapeake Bay that gave me about 5.5 amps for 6 or
        Message 3 of 6 , Nov 17
          Last season I had two 50 watt panels running through a Morningstar Duo (pwm) controller. At the top of the Chesapeake Bay that gave me about 5.5 amps for 6 or 7 hours each day. It was enough to run the isotherm refrigerator but still required running the engine to keep all the batteries charged. The boat is on a mooring, no shore power at all.
          I added another 100 watt panel ( all mounted astern on top of the bimini) for a total of 200 watts. Batteries are two 6 volt for the house bank and a 12 volt starter/emergency bank. Everything is connected to a Blue Star ACR.
          Now I can leave the fridge on while on the mooring if I want; on a cruise the fridge will run all the time for the duration of the trip. 
          Denis
          Brazen Article #108
          1991 Catalina 28 
        • Mike Smalter
          Cecilia, I agree that a cruising sailboat should use an MPPT controller for maximum efficiency/power generation, but for a user with minimal power needs, a PWM
          Message 4 of 6 , Nov 17

            Cecilia, I agree that a cruising sailboat should use an MPPT controller for maximum efficiency/power generation, but for a user with minimal power needs, a PWM at $30 can be an effective solution. I have a 100W panel and PWM controller that powered my Engel cooler 24/7 all summer long. The Engel draws 2.5 amps when running and draws only 9 amp hours a day. On a sunny day the controller is on trickle charge mode by 11AM or noon. I’ve read that the MPPT’s are up to 30% more efficient than PWM’s, but that is when they are cool. The difference is more like 10-20% in the summer when we use our boats. However I respect you do this for a living, so please correct me if I am wrong.

             

            Bob—My controller has a load circuit that measures battery voltage and shuts off the load if the voltage drops to a certain level. That prevents the battery from being discharged too much. The load circuit is re-energized when the controller senses the battery is being charged again (either by solar or alternator). I connected a  cigarette lighter socket to the load contacts and plug the 12V plug from the cooler into it. That way I don’t have to worry about over discharging the battery. When you hook the solar panel to the controller and the controller to the battery, make sure you size the wires for less than 3% voltage drop, or else you will be throwing energy away.

             

            Mike Smalter

             

            From: Cecilia Potts ceciliapotts@... [catalina28]
            Sent: Friday, November 17, 2017 8:20 AM
            To: catalina28@yahoogroups.com
            Subject: Re: [Catalina 28] Solar panels

             

             

            Never directly connect solar panels to a 12 V battery, damage will occur. I work for a solar company that specializes in portable power solutions for defense and cruising sailboats. 

             

            Some panels have solar charge regulators built in, but those are usually the mA variety or lower voltage.

             

            Pick up a BlueSky Solar charge controller ~$180. These are MPPT (maximum power point tracking) and for your and many other applications, far superior to their PWM cousins.

             

            Overcast and any shading will significantly impact your panel output. Panels are rated using STC which is standard testing conditions at 77 degrees F and a specific atmosphere. (Haven't had enough coffee yet to remember). You can determine very precise amounts of maximum irradiance at NREL.com for your location, but for spitball estimation, we use 5 hours of solar for anything in the Southern US and 4 hours for our friends in the Northern tier. 

             

            So, for your draw using the V x A = W math...which assumes 100 percent efficiency (and nothing is 100 efficient) ....and based on 8 hours of cooler run time...your draw is 32 Ah to run cooler.. A 100 W, 12 W panel will provide ~8.3 A per hour. Using 5 hours of direct sun that's ~41 Ah of power gen. Used in concert with an MPPT solar charge controller, that should be adequate to support the load and even put a little more in the bank. Just a numbers game. Important, too to balance solar with battery bank size so you don't over/under cycle batteries, but that's another post for another time.

             

            You can email me directly at work if you or anyone has any more questions cpotts@...

            I'm happy to help!!! 

            You all have helped me a lot so far on other things

             

            Ceal #13 s/v Wooden Shoe


            On Nov 16, 2017, at 11:57 PM, bob storrar bobst9234@... [catalina28] <catalina28@yahoogroups.com> wrote:

             

            I have a portable 12v cooler that draws 50 watts or 4 amps. Has anyone tried to use a solar panel to power a 12v cooler all day? Like when you are at anchor  and you will be gone all day.

             

            Will an overcast day have a significant effect on the output of the solar panel?  Do I need a voltage regulator of some kind?  Should I run the solar panel wires to the house battery and draw of the that?

             

             

             Is there any reason  that I can't plug the panel directly to the cooler and walk away for the day?

             

            Thanks in advance for your input

            Bob

            Moon Dance #177



            Sent from Yahoo Mail for iPhone

             

          • Cecilia Potts
            Mike, I think I fat fingered the word cooler in my reply. That s actually not the biggie. Of course everything likes cooler, but the biggie in the MPPT vs
            Message 5 of 6 , Nov 18
              Mike,
              I think I fat fingered the word "cooler" in my reply. That's actually not the biggie. Of course everything likes cooler, but the biggie in the MPPT vs PWM performance is taking advantage of a solar panel or array's output. A 12 V solar panel had a much higher Voc (open circuit voltage) than 12 V. PWM chargers don't take advantage of that whereas MPPT chargers do. To charge a battery, the voltage of the incoming current must be greater than the voltage of the battery. PWM chargers regulate that charge closer to the voltage of the battery. That means the current is less and the battery charges slower. At that point, you're not accessing the full potential of your panels. The MPPT charge controller uses an algorithm to maximize more of the panels rated open circuit voltage. This also increase the current, which allows you to charge faster. Where the MPPT is especially more advantageous than PWM is in lower light and shaded conditions. 

              As long as the load is supported, and there's enough power generated that's the most important thing. :-)

              On Nov 17, 2017, at 10:20 AM, Mike Smalter msmalter@... [catalina28] <catalina28@yahoogroups.com> wrote:

               

              Cecilia, I agree that a cruising sailboat should use an MPPT controller for maximum efficiency/power generation, but for a user with minimal power needs, a PWM at $30 can be an effective solution. I have a 100W panel and PWM controller that powered my Engel cooler 24/7 all summer long. The Engel draws 2.5 amps when running and draws only 9 amp hours a day. On a sunny day the controller is on trickle charge mode by 11AM or noon. I’ve read that the MPPT’s are up to 30% more efficient than PWM’s, but that is when they are cool. The difference is more like 10-20% in the summer when we use our boats. However I respect you do this for a living, so please correct me if I am wrong.

               

              Bob—My controller has a load circuit that measures battery voltage and shuts off the load if the voltage drops to a certain level. That prevents the battery from being discharged too much. The load circuit is re-energized when the controller senses the battery is being charged again (either by solar or alternator). I connected a  cigarette lighter socket to the load contacts and plug the 12V plug from the cooler into it. That way I don’t have to worry about over discharging the battery. When you hook the solar panel to the controller and the controller to the battery, make sure you size the wires for less than 3% voltage drop, or else you will be throwing energy away.

               

              Mike Smalter

               

              From: Cecilia Potts ceciliapotts@... [catalina28]
              Sent: Friday, November 17, 2017 8:20 AM
              To: catalina28@yahoogroups.com
              Subject: Re: [Catalina 28] Solar panels

               

               

              Never directly connect solar panels to a 12 V battery, damage will occur. I work for a solar company that specializes in portable power solutions for defense and cruising sailboats. 

               

              Some panels have solar charge regulators built in, but those are usually the mA variety or lower voltage.

               

              Pick up a BlueSky Solar charge controller ~$180. These are MPPT (maximum power point tracking) and for your and many other applications, far superior to their PWM cousins.

               

              Overcast and any shading will significantly impact your panel output. Panels are rated using STC which is standard testing conditions at 77 degrees F and a specific atmosphere. (Haven't had enough coffee yet to remember). You can determine very precise amounts of maximum irradiance at NREL.com for your location, but for spitball estimation, we use 5 hours of solar for anything in the Southern US and 4 hours for our friends in the Northern tier. 

               

              So, for your draw using the V x A = W math...which assumes 100 percent efficiency (and nothing is 100 efficient) ....and based on 8 hours of cooler run time...your draw is 32 Ah to run cooler.. A 100 W, 12 W panel will provide ~8.3 A per hour. Using 5 hours of direct sun that's ~41 Ah of power gen. Used in concert with an MPPT solar charge controller, that should be adequate to support the load and even put a little more in the bank. Just a numbers game. Important, too to balance solar with battery bank size so you don't over/under cycle batteries, but that's another post for another time.

               

              You can email me directly at work if you or anyone has any more questions cpotts@...

              I'm happy to help!!! 

              You all have helped me a lot so far on other things

               

              Ceal #13 s/v Wooden Shoe


              On Nov 16, 2017, at 11:57 PM, bob storrar bobst9234@... [catalina28] <catalina28@yahoogroups.com> wrote:

               

              I have a portable 12v cooler that draws 50 watts or 4 amps. Has anyone tried to use a solar panel to power a 12v cooler all day? Like when you are at anchor  and you will be gone all day.

               

              Will an overcast day have a significant effect on the output of the solar panel?  Do I need a voltage regulator of some kind?  Should I run the solar panel wires to the house battery and draw of the that?

               

               

               Is there any reason  that I can't plug the panel directly to the cooler and walk away for the day?

               

              Thanks in advance for your input

              Bob

              Moon Dance #177



              Sent from Yahoo Mail for iPhone

               

              <1906E66ED8374DEF81B6EC01DF55D25D.png>
            • bob storrar
              blockquote, div.yahoo_quoted { margin-left: 0 !important; border-left:1px #715FFA solid !important; padding-left:1ex !important; background-color:white
              Message 6 of 6 , Nov 19
                Thanks to all who responded. It seems as though I’ll be doing a bit more studying. I was a little  naive thinking I could just plug something in without a lot of thought. But can that even happen when you are installing something on a boat?

                Enjoy your thanksgiving 

                Bob
                Moon Dance #177


                Sent from Yahoo Mail for iPhone

                On Saturday, November 18, 2017, 3:11 PM, Cecilia Potts ceciliapotts@... [catalina28] <catalina28@yahoogroups.com> wrote:

                 

                Mike,
                I think I fat fingered the word "cooler" in my reply. That's actually not the biggie. Of course everything likes cooler, but the biggie in the MPPT vs PWM performance is taking advantage of a solar panel or array's output. A 12 V solar panel had a much higher Voc (open circuit voltage) than 12 V. PWM chargers don't take advantage of that whereas MPPT chargers do. To charge a battery, the voltage of the incoming current must be greater than the voltage of the battery. PWM chargers regulate that charge closer to the voltage of the battery. That means the current is less and the battery charges slower. At that point, you're not accessing the full potential of your panels. The MPPT charge controller uses an algorithm to maximize more of the panels rated open circuit voltage. This also increase the current, which allows you to charge faster. Where the MPPT is especially more advantageous than PWM is in lower light and shaded conditions. 

                As long as the load is supported, and there's enough power generated that's the most important thing. :-)

                On Nov 17, 2017, at 10:20 AM, Mike Smalter msmalter@... [catalina28] <catalina28@yahoogroups.com> wrote:

                 

                Cecilia, I agree that a cruising sailboat should use an MPPT controller for maximum efficiency/power generation, but for a user with minimal power needs, a PWM at $30 can be an effective solution. I have a 100W panel and PWM controller that powered my Engel cooler 24/7 all summer long. The Engel draws 2.5 amps when running and draws only 9 amp hours a day. On a sunny day the controller is on trickle charge mode by 11AM or noon. I’ve read that the MPPT’s are up to 30% more efficient than PWM’s, but that is when they are cool. The difference is more like 10-20% in the summer when we use our boats. However I respect you do this for a living, so please correct me if I am wrong.

                 

                Bob—My controller has a load circuit that measures battery voltage and shuts off the load if the voltage drops to a certain level. That prevents the battery from being discharged too much. The load circuit is re-energized when the controller senses the battery is being charged again (either by solar or alternator). I connected a  cigarette lighter socket to the load contacts and plug the 12V plug from the cooler into it. That way I don’t have to worry about over discharging the battery. When you hook the solar panel to the controller and the controller to the battery, make sure you size the wires for less than 3% voltage drop, or else you will be throwing energy away.

                 

                Mike Smalter

                 

                From: Cecilia Potts ceciliapotts@... [catalina28]
                Sent: Friday, November 17, 2017 8:20 AM
                To: catalina28@yahoogroups.com
                Subject: Re: [Catalina 28] Solar panels

                 

                 

                Never directly connect solar panels to a 12 V battery, damage will occur. I work for a solar company that specializes in portable power solutions for defense and cruising sailboats. 

                 

                Some panels have solar charge regulators built in, but those are usually the mA variety or lower voltage.

                 

                Pick up a BlueSky Solar charge controller ~$180. These are MPPT (maximum power point tracking) and for your and many other applications, far superior to their PWM cousins.

                 

                Overcast and any shading will significantly impact your panel output. Panels are rated using STC which is standard testing conditions at 77 degrees F and a specific atmosphere. (Haven't had enough coffee yet to remember). You can determine very precise amounts of maximum irradiance at NREL.com for your location, but for spitball estimation, we use 5 hours of solar for anything in the Southern US and 4 hours for our friends in the Northern tier. 

                 

                So, for your draw using the V x A = W math...which assumes 100 percent efficiency (and nothing is 100 efficient) ....and based on 8 hours of cooler run time...your draw is 32 Ah to run cooler.. A 100 W, 12 W panel will provide ~8.3 A per hour. Using 5 hours of direct sun that's ~41 Ah of power gen. Used in concert with an MPPT solar charge controller, that should be adequate to support the load and even put a little more in the bank. Just a numbers game. Important, too to balance solar with battery bank size so you don't over/under cycle batteries, but that's another post for another time.

                 

                You can email me directly at work if you or anyone has any more questions cpotts@...

                I'm happy to help!!! 

                You all have helped me a lot so far on other things

                 

                Ceal #13 s/v Wooden Shoe


                On Nov 16, 2017, at 11:57 PM, bob storrar bobst9234@... [catalina28] <catalina28@yahoogroups.com> wrote:

                 

                I have a portable 12v cooler that draws 50 watts or 4 amps. Has anyone tried to use a solar panel to power a 12v cooler all day? Like when you are at anchor  and you will be gone all day.

                 

                Will an overcast day have a significant effect on the output of the solar panel?  Do I need a voltage regulator of some kind?  Should I run the solar panel wires to the house battery and draw of the that?

                 

                 

                 Is there any reason  that I can't plug the panel directly to the cooler and walk away for the day?

                 

                Thanks in advance for your input

                Bob

                Moon Dance #177



                Sent from Yahoo Mail for iPhone

                 

                <1906E66ED8374DEF81B6EC01DF55D25D.png>
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