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  • I just want to power a laptoo

    I'm completely new to Solar technology so my knowledge is limited.

    I need a simple kit to power a 65w laptop voa it's own standard wall socket charger. And with 2 or 3 hours storage.

    As far as i've been told so far i just need to buy a 100w -150w Solar Panel with controller. And a power inverter with storage.

    is this correct?

    My budget is

  • #2
    Originally posted by nvisibl View Post
    I'm completely new to Solar technology so my knowledge is limited.

    I need a simple kit to power a 65w laptop voa it's own standard wall socket charger. And with 2 or 3 hours storage.

    As far as i've been told so far i just need to buy a 100w -150w Solar Panel with controller. And a power inverter with storage.
    OK first off if you reduce the charge power that helps. Dells, for example, allow two different charge rates - I think it's 60 and 90 watts.

    Secondly it's a lot easier to go DC/DC. Use a panel, a smallish battery and a DC/DC converter to provide power to your laptop. They are available off the shelf, often called "cigarette light adapters" or "auto adapters." They will generally work on 10-16 volts, although some have a higher minimum (since car systems are almost always at 13.8 volts.)

    Next decide where you want to use it, what sort of sun you will see and what time of the day you will use it. If it's 10am-2pm in a good location then you can count on 70-80% of the rated power of the panel assuming good weather. Winter some place it's warm and humid? You might get less. Summer at high altitude in the snow? You might get close to 100%. It's possible to size a system to run when it's cloudy out but that takes a lot more panel - and not all clouds are the same.

    Do you want a portable panel or is this a fixed mount? Fixed mounts allow very cheap panels to be used (i.e. low cost per watt.) Portable panels are much more expensive.

    As you go through the design you will end up with a power requirement (65W) an energy requirement (i.e. 65W for 4 hours, or 260 watt-hours, per day) and other requirements that you are going to add based on your own needs (what sun you'll expect to see, what time, what location, max weight, max size etc.) Your energy use per day will determine your panel sizing, and your battery will have to match that to within loose guidelines based on chemistry chosen, life desired and things like days of autonomy (how long you want to be able to use your laptop if its cloudy for X days in a row.)

    Anyway if you want to proceed, let us know where you will be using it, what time you will be using it, weight limits, size limits, whether it's fixed or portable, how many hours a day you need to use your laptop and your price limits.

    Oh and BTW when you reply try not to use much punctuation; the website barfs on many kinds of punctuation. Safest bet is to write it in Notepad or some other ASCII-only editor and then copy and paste it in.

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    • #3
      Originally posted by jflorey2
      Secondly it's a lot easier to go DC/DC. Use a panel, a smallish battery and a DC/DC converter to provide power to your laptop.
      This is the way to go, it is so much more electrically efficient than DC-AC-DC, that the size of your equipment
      can be scaled way down for similar results. Bruce Roe

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      • #4
        I had to just proceed with purchase earlier as i need something quick. And wasn't sure if i was going to receive reply here.

        i bought a 150w panel with charge controller and a 500w sine wave inverter.

        i am in Glasgow Scotland. Definately not the sunniest place.

        i'm also in a tent beneath tree though the tree cover isn't thick. There is clear sky space. I may be able to fit it part way up a tree.

        I want to use the laptop for between 6 - 8 hours each day.

        i don't have any storage a d recognise i may need to get some.

        thanks for your replies

        Comment


        • #5
          Originally posted by nvisibl View Post
          I had to just proceed with purchase earlier as i need something quick. And wasn't sure if i was going to receive reply here.

          i bought a 150w panel with charge controller and a 500w sine wave inverter.

          i am in Glasgow Scotland. Definately not the sunniest place.

          i'm also in a tent beneath tree though the tree cover isn't thick. There is clear sky space. I may be able to fit it part way up a tree.

          I want to use the laptop for between 6 - 8 hours each day.

          i don't have any storage a d recognise i may need to get some.

          thanks for your replies
          OK. If you are in a tent beneath a tree then you can't use solar, unless you put the panel in the sun and run some wiring. You cannot use solar with a "mostly sunny" space under a tree (or in a tree.) With a 150W 12V panel you'll get about 6 amps of charge power, which means you'll need a battery between 50 and 70 amp hours. The Crown CRV55 might work OK for you. You do not want to discharge more than about 50% (i.e. never let OCV get below about 12V.)

          You CANNOT use the inverter without a battery. Make sure to protect the battery with proper fusing and cabling; even a small battery like that can start fires.

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          • #6
            Okay thanks

            i've found another spot for the panel on complete wide open space without shade.

            i now have the panel, charge controller and inverter but no battery.

            i didn't realise i needed a battery. Seller didn't inform me of that. Ho hum

            i wasn't sure if i needed to hook up the inverter to the controllers load or battery section.

            Is it 100% fact that i need a battery. And if so which one would you recommend?

            Thank you

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            • #7
              Crown CRV... got you, thanks

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              • #8
                I'm unable to find any battery of that model.

                Is it okay for me to buy any 12v battery that is 100ah?

                Sorry for my complete noobnes. I'm very thankful for your time

                Comment


                • #9
                  Originally posted by nvisibl View Post
                  I'm unable to find any battery of that model.
                  Is it okay for me to buy any 12v battery that is 100ah?
                  Probably. It will tend not to charge fully, so you might need another panel. Might be OK if you allow the occasional stretch of several days to fully recharge (i.e. no use on those days.) The issue is that you want to provide the battery at LEAST a C/13 rate of charge, which is AH divided by 13. So at 100 AH you'd need 7.7 amps. Your 150W will give you 8.3 amps in perfectly ideal conditions with that PWM controller you have. You will never see ideal conditions, so 6.6 amps is a more likely real-world charge current - which isn't quite enough. But it's close enough that if you let it charge for a few days in the sun with no load you may get the battery close to full charge.

                  BTW that's important because not fully charging a battery is hard on it.

                  Get a flooded or AGM battery; do NOT use a gel battery. Those are great for UPSes but not so great for cyclic applications.

                  Comment


                  • #10
                    Originally posted by nvisibl View Post
                    I'm unable to find any battery of that model.

                    Is it okay for me to buy any 12v battery that is 100ah?

                    Sorry for my complete noobnes. I'm very thankful for your time
                    Both of my batteries were 12V and 100 Ah each. I bought two Durecell Ultra's. I wanted 100 Ah, so I bought two so that 100 Ah would be 50% of both. Do you have a Kill A Watt device to check the actual wattage used?

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                    • #11
                      Hi guys, thanks

                      Would then a 75ah 12v battery do the trick?

                      Really i'm just looking for the right spec battery to use with the current 150w Solar Panel setup that will help me power the 65w laptop

                      I live in Scotland, so for more than 50% of the year the weather will be grey, wet, and overcast

                      Comment


                      • #12
                        Originally posted by nvisibl View Post
                        Hi guys, thanks

                        Would then a 75ah 12v battery do the trick?

                        Really i'm just looking for the right spec battery to use with the current 150w Solar Panel setup that will help me power the 65w laptop

                        I live in Scotland, so for more than 50% of the year the weather will be grey, wet, and overcast
                        Anything will work. It all depends on how much time you use it. Instead of running something for 6 to 8 hours non stop, you may be only able to run it for an hour or two with a single 75 Ah. You can only run a single battery down 50% before it does permanent damage. You could get two 75 Ah batteries and wire them in parallel to get longer use. I've seen Renogy AGM 100 Ah ones go for like $200. So a 75 Ah should be cheaper.

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                        • #13
                          Awesome, thanks

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                          • #14
                            All is good. I am setup now

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                            • #15
                              Originally posted by nvisibl View Post
                              All is good. I am setup now
                              Just get something to measure the voltage of the battery. Once you get below 10.7 volts, stop using it until it is recharged again. I had no problems running an iMac off of my 200 Ah of batteries and 310 watt solar panel. What kind of laptop do you have? Those usually use considerably less power. As long as you're using the laptop while solar power is coming in, you should easily get many hours of use from that per day. What country do you live in?

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