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Advice Needed: Want to build a solar panel LED light setup for entire backyard.

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  • Advice Needed: Want to build a solar panel LED light setup for entire backyard.

    I am hoping someone can shed some light on the setup I want to build. I have multiple large strands of various LED string lights that will take up most of my backyard. Each string is around 10m / 100 small LED lights each. From what I have read they use 11-15W each. I will be using at least 10 strings if not more later. Figure 5-6 hours of usage per night. Automatic shut-off. What kind of panel, controller and battery should I be looking at getting? I will need room to grow. I am fine with doing the electrical myself.

    I would really like to make it a modular plug in system so that if I purchase another string, I can simply plug it into a board of some sort instead of wiring every string together on one connection. Can I get this type of setup for each individual connection?

  • #2
    Welcome.

    Trying to "grow" a system to handle a "few" more strings later, does not work. I must be designed from the beginning.

    I'll assume 120VAC LED holiday light strings that are UL certified for outdoor use

    10w each. 20 strings = 200w load. x 6 hours = 1200 watt hours per night.

    Daily use, unless it's cloudy, and you are not likely to be outdoors that night.

    3 nights of use stored in the batteries (33% discharge on a single normal day)

    1 sunny day harvest will recharge 2 days of usage (not a mission critical, does not need to recharge 3 days of use on 1 sunny day)

    Single 12v deep cycle battery 90ah = 1080wh too small.
    pair of 6v 205ah golf cart batt = 2460 wh = only 2 nights storage, but going larger gets progressively more expensive

    PV panels to harvest 5,000wh in 4 hours solar time = 1250 watts Panel racks. Inverter. Charge controller $$$$$$$$$$$$

    Houston, we have a problem. An expensive one,

    Or some direct burial power cord to the yard to power the lights = <$200
    All for $89 per year worth of electric ? ( at 20¢ per KWh )
    Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister

    Comment


    • #3
      Unfortunately what Mike has stated is correct. You have now crossed into the twilight zone to learn that a solar/battery system is expensive for small loads and really expensive for anything exceeding 1kWh of daily usage.

      And unlike most things a solar/battery system can't "grow" without throwing away some of the existing hardware/batteries and purchasing all new and bigger stuff.

      In most parts of the US it will always be less expensive to run a power line from the home to your outdoor loads.

      The best payback for solar is to go with an approved grid tie system.

      By the way, hello and welcome to Solar Panel Talk

      Comment


      • #4
        Thanks again for the quick response! Perhaps I should (split) the load to say 3 smaller setup's around the yard? The main idea here is not so much the cost for the material and annual power usage as much as the freedom to plant these around the property without the need for power coming from the house and digging trenches.

        If the panel, inverter and controller are just small enough to be housed in a water proof/Resistant enclosure at each spot, it gives me the flexibility to place the strips pretty much anywhere I want. If that were the case I could perhaps run (4) per solar box lets call it and that should give me the proper amount of LED's for the given area.

        If I go with that scenario what's the most efficient small panel to run that load each and the controller and inverter ideal for the setup? Thank again for the help. This is going to be a fun project.

        Comment


        • #5
          Originally posted by aztecsurf View Post
          Thanks again for the quick response! Perhaps I should (split) the load to say 3 smaller setup's around the yard? The main idea here is not so much the cost for the material and annual power usage as much as the freedom to plant these around the property without the need for power coming from the house and digging trenches.

          If the panel, inverter and controller are just small enough to be housed in a water proof/Resistant enclosure at each spot, it gives me the flexibility to place the strips pretty much anywhere I want. If that were the case I could perhaps run (4) per solar box lets call it and that should give me the proper amount of LED's for the given area.

          If I go with that scenario what's the most efficient small panel to run that load each and the controller and inverter ideal for the setup? Thank again for the help. This is going to be a fun project.
          Even if you go with a set of lights that only requires 300watt hours a day you can easily spend up to $1000 for each set including solar panels, batteries, charger and inverter if those are 120volt lights.

          Are you looking for approval from friends and family that you can light your yard using solar or do you feel this is going "green"?

          For simplicity sake (and cost) getting a few 50ft extension cords will do the job without trenching.

          Comment


          • #6
            My lights may not require that much power. These are the typical (tear drop) style string lights. The box reads:

            -- Voltage:110V(US standard).
            -- Length: 10 M. 100 LED
            -- Power:6W.

            However if I google the average (10M LED Light) string it says up to 15W.

            These are very small lights on each strand. I have a few of the cheap solar panel included models to run each string, but they are way under powered and the lights are always too dim when they turn on. Most likely due to the cheap 6x6 inch panel and battery they come with.

            Maybe the best route is to get the smallest quality panel and a small controller to run 3-4 of these on it and see what the cost is after the total build? This is more of a test in the beginning I think to measure the power / size of the unit needed.

            Comment


            • #7
              Originally posted by aztecsurf View Post
              My lights may not require that much power. These are the typical (tear drop) style string lights. The box reads:

              -- Voltage:110V(US standard).
              -- Length: 10 M. 100 LED
              -- Power:6W.

              However if I google the average (10M LED Light) string it says up to 15W.

              These are very small lights on each strand. I have a few of the cheap solar panel included models to run each string, but they are way under powered and the lights are always too dim when they turn on. Most likely due to the cheap 6x6 inch panel and battery they come with.

              Maybe the best route is to get the smallest quality panel and a small controller to run 3-4 of these on it and see what the cost is after the total build? This is more of a test in the beginning I think to measure the power / size of the unit needed.
              Lets say each string is rated 10w and you have 4 of them used for 5 hours a night. That comes to about 200 watt hours. You will need a 12 volt battery around 85Ah, a 150watt solar panel, 15amp charge controller and 200 watt inverter plus wiring, fuses, connectors and mounting bracket for the panel.

              You can google prices for those items. You might be able to get all that for around $600.

              Comment


              • #8
                Excellent! I have a number to work with. Let me break this down to see the size / cost.

                "You will need a 12 volt battery around 85Ah, a 150watt solar panel, 15amp charge controller and 200 watt inverter"

                1. What is the smallest 12V Battery at this rating I can buy? Ideally it will be in the same housing as the panel, behind it and self contained. Perhaps a sealed boxed area behind the panel that can be accessed by lifting one side up from a latch to access all the components. Do they make flat batteries? Or cylindrical?

                2. 150W panel. What sizes do these come in? Or what is the smallest most efficient panel to do the job? This is going to be sitting somewhere in the back yard disguised if possible but access to the sun.

                3. Since these lights basically are two wires across the span, I would imagine I am going to cut the end leads to the size I want and wire them into the inverter. Is there a (power board) of some sort I can get that will make this less messy and allow me to connect each light strand to contacts on the board?

                Great information here. Yes, the price seems steep, but I will start researching parts and costs as this comes to a close.

                Comment


                • #9
                  Originally posted by aztecsurf View Post
                  Excellent! I have a number to work with. Let me break this down to see the size / cost.

                  "You will need a 12 volt battery around 85Ah, a 150watt solar panel, 15amp charge controller and 200 watt inverter"

                  1. What is the smallest 12V Battery at this rating I can buy? Ideally it will be in the same housing as the panel, behind it and self contained. Perhaps a sealed boxed area behind the panel that can be accessed by lifting one side up from a latch to access all the components. Do they make flat batteries? Or cylindrical?

                  2. 150W panel. What sizes do these come in? Or what is the smallest most efficient panel to do the job? This is going to be sitting somewhere in the back yard disguised if possible but access to the sun.

                  3. Since these lights basically are two wires across the span, I would imagine I am going to cut the end leads to the size I want and wire them into the inverter. Is there a (power board) of some sort I can get that will make this less messy and allow me to connect each light strand to contacts on the board?

                  Great information here. Yes, the price seems steep, but I will start researching parts and costs as this comes to a close.
                  You might find a seal AGM battery rated 85 to 100Ah. There are also some "high end" sealed FLA type made by Optima. There are plastic battery boxes for about $15 that will fit either of those type batteries.

                  Most 150watt panels are the same size about 2 1/2 feet wide by 6 ft tall. Some are shorter but also wider depending on the brand.

                  The Inverter usually has a receptacle similar to what you find on the wall of your house. So if those LED lights already have a plug on one end they should be able to connect to the inverter.

                  The 15amp charge controller is small and has terminals to connect the solar panel and batteries. Since you want to go low cost for fun you won't have to spend much but it has to be protected from the weather so you might need another plastic box to put it in.

                  Like I said you can find these items using google but if you can get some junk if you do not buy quality items which cost more than the cheaper ones.

                  Comment


                  • #10
                    Ok, after going over some of the specs of these lights and requirements I think I was able to simplify this. First I don't believe I need the inverter at all. All my LED lights are DC and basically we are going from the panel - controller - battery - step down DC-DC converter for each strand. No AC in the chain. I will be using bare wire on the LED strands with no AC adapters. Some of the DC step down models have USB fittings on the output and I can simply wire each strands two wires into a USB connector. That would make this more of a modular setup.

                    Some of my lights that are longer require up to 120 Volts, 0.25 Amps. So if I am correct do I calculate the 0.25 into how many hours I will want and that will determine the battery storage?

                    Thanks..

                    Comment


                    • #11
                      Originally posted by aztecsurf View Post
                      Ok, after going over some of the specs of these lights and requirements I think I was able to simplify this. First I don't believe I need the inverter at all. All my LED lights are DC and basically we are going from the panel - controller - battery - step down DC-DC converter for each strand. No AC in the chain. I will be using bare wire on the LED strands with no AC adapters. Some of the DC step down models have USB fittings on the output and I can simply wire each strands two wires into a USB connector. That would make this more of a modular setup.

                      Some of my lights that are longer require up to 120 Volts, 0.25 Amps. So if I am correct do I calculate the 0.25 into how many hours I will want and that will determine the battery storage?
                      You are way ahead if you can power the LEDs directly from low voltage DC. Devices for converting DC
                      to AC and back to DC at lower power levels are notorious for poor efficiency. What is the voltage and
                      current of those?

                      120V X 0.25A = 30W, which is bigger than you mentioned before. Bruce Roe

                      Comment


                      • #12
                        Ok, those I mentioned are the outdoor lights that have a solar power unit connected. I could only find info on Google for something close since its not marked on the unit. The info I got may be incorrect.

                        However, I remember I also have a 100LED 33FT strand for indoors that uses an AC Adapter. Here is the output on that device = DC 5V - 1000mA. That string is very close to my outdoor setup so I would think that's going to be the average load needed per strand.

                        Of course if I need to I can step it down with a small converter.

                        This seems to be the smallest 100W panel I can find that gets good ratings: http://www.ebay.com/itm/271222475269...%3AMEBIDX%3AIT

                        Comment


                        • #13
                          Originally posted by aztecsurf
                          However, I remember I also have a 100LED 33FT strand for indoors that uses an AC Adapter. Here is the output on that device = DC 5V - 1000mA. That string is very close to my outdoor setup so I would think that's going to be the average load needed per strand.

                          Of course if I need to I can step it down with a small converter.
                          That is 5V X 1A = 5W. For a couple bucks you can pick up a very efficient buck regulator to
                          run them from 12V. Bruce Roe

                          Comment


                          • #14
                            Originally posted by aztecsurf View Post
                            Ok, after going over some of the specs of these lights and requirements I think I was able to simplify this. First I don't believe I need the inverter at all. All my LED lights are DC and basically we are going from the panel - controller - battery - step down DC-DC converter for each strand. No AC in the chain. I will be using bare wire on the LED strands with no AC adapters. Some of the DC step down models have USB fittings on the output and I can simply wire each strands two wires into a USB connector. That would make this more of a modular setup.

                            Some of my lights that are longer require up to 120 Volts, 0.25 Amps. So if I am correct do I calculate the 0.25 into how many hours I will want and that will determine the battery storage?

                            Thanks..
                            I am sorry. It is getting hard to follow what you need since your hardware description keeps changing.

                            I don't want to send you down the wrong path on purchasing hardware if I really don't know what your LED lights need to be powered or how many watts they burn up.

                            Comment


                            • #15
                              Thank you, I appreciate your help on my questions. The issue is I have several different light strip lengths and power requirements I have found. I have a indoor strip that requires 5V - 500mA that is only 10M. I have the same strip for outdoor with no output on the label so I assume it's the same.

                              Since these strips are all very close to each other as far as needed power depending on the length and LED count should I just buy a few of these converters and step each strand to the proper voltage it wants?

                              http://www.ebay.com/itm/DC-DC-Buck-V...item2a52ce74d3

                              It looks like I am getting close. Just need to pick the correct battery and panel to match.

                              Comment

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