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Post by bupkis on Nov 14, 2018 3:13:17 GMT
First QUESTIONS: What would be the advantage of wiring 3 pairs in series and then into parallel? It still combines to 24v/15.6a right? Or would you wire one set of 3 in series and then another set of 3 in series and connect the 2 sets in parallel? Wouldn't that math out to 36v/10.4a? Is this where your recommendation for bigger wire gauge comes in?
if we use '12v' for one panel then 3 is series in 36v x 5.2a - this is one 'string of 3' if you parallel another 'string of 3' the result is 36v x 10.4A That seems to be lower amps than your 3 is parallel (12x15.6) in series with another 3 in parallel (12x15.6) result in 24x15.6. That is the same as 3 strings of 2. Please drop the parallel then series concept! series than parallel is the norm. Strings of series panels connected in parallel. If one string is totally shaded the other string still works, if you did parallel then series, if on string was shaded then all output would stop! As you can see 2 strings of 3 results is lower current (same wattage) and that is what determines voltage drop - current - amps. So ya connect three panel is series (5.2A) then run 10g 15' where the other three panels in series combine (10g, 15', 5.2A). Now they are combined as 10.4A. This is where you might need to increase wire gauge depending on how far it is to the controller. No fusing of the strings would be needed! How far is it from the combined strings to the controller? Now the controller is gonna bump up current to say a max of 45A (600w) so you would need 6g from the controller to batteries unless it is a long run and then you would go with larger wire. This is the most critical voltage drop section. "New QUESTION: My controller manual mentions using 6g/90C or 4g/75C minimum for "carrying the system current" Does that mean out of the charge controller going to the battery?" yes, they are suggesting that for 60A or ~800w, you only have 600w or 45A. "Supplies: You mentioned that if I went with series into strings and then wire 2 strings into parallel that I'd need to boost the gauge: "I also agree he must at each panel's outputs increase AWG to at least 8AWG, then combine them all into 6AWG before they drop into the house.... He will need 7 pairs of 10/12 to 8 AWG MC4 conversion connectors, fusing for each panel, a combiner box, and lengths of wire as required." This is bunch of BS which has previously been refuted, it is total ignorance. It had to do with paralleling all 7 panels and is garbage.
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Post by swampmonster on Nov 14, 2018 7:47:12 GMT
Wow, guys, THANKS! Great detailed responses! And thank you for the compliment on my Tiny House & on my choice of controller.
Irrelevant Point of interest: I do have a total of 8 panels. But 1 is already installed on my 6x10 ft "Cottage Camper" I built 5 years ago. I had purchased 8 to put onto a cabin I built in the mountains, but I sold the cabin before I ever installed the solar. So that's why I have 7 left now for my 20ft THOW.
OK, I do have a basic knowledge of series/parallel math, so I follow what you're saying. I will "ditch one" panel for now and make 2 sets of 3.
The Renogy panels I have are 100watt/12v/5.2amp. The controller max Voc is 125 so no, I can't put them all in series, I agree. Nor all in parallel.
First QUESTIONS: What would be the advantage of wiring 3 pairs in series and then into parallel? It still combines to 24v/15.6a right? Or would you wire one set of 3 in series and then another set of 3 in series and connect the 2 sets in parallel? Wouldn't that math out to 36v/10.4a? Is this where your recommendation for bigger wire gauge comes in?
Supplies: You mentioned that if I went with series into strings and then wire 2 strings into parallel that I'd need to boost the gauge:
"I also agree he must at each panel's outputs increase AWG to at least 8AWG, then combine them all into 6AWG before they drop into the house.... He will need 7 pairs of 10/12 to 8 AWG MC4 conversion connectors, fusing for each panel, a combiner box, and lengths of wire as required."
I'm still thinking to wire the 3 in parallel (12v/15.6a) and then the 2 sets together in series. That brings its math to 24v/15.6a. Wouldn't this allow me to keep using 10g between the panels as well as the 12ft drop into the controller? Would you still recommend bigger wires if I did it my way = 3 in parallel, 3 in parallel and then connected into series? Or is there a reason you'd series first, then parallel?
And once you help me understand my choices at this point, then we can ponder a new question: New QUESTION: My controller manual mentions using 6g/90C or 4g/75C minimum for "carrying the system current" Does that mean out of the charge controller going to the battery? And yes, I will put the charge controller near the battery and also near the inverter.
I have one AGM battery now but will get at least one more. Being that they are sealed, do I still want to put the cc and inverter in a separate compartment? The battery lives inside the storage bench/couch.
Again, gentlemen, I am most grateful for your knowledge and input! Thanks! LOL, us guys sometimes piss on each others sneakers, but that's ok as long as in the end someone gets help. Sounds like you have a quick grasp of the details and will finger it out.....BUT, you still need to think carefully about exactly how you want to split the panels into arrays. You already fingered out the different values when configured into two 3 panel arrays, or three 2 panel arrays and understand each array should be connected in series, then those arrays combined into parallel feeds to your controller...COOL! AND, you learned from bupkis, to FIRST series your panels into an array, and THEN then parallel all the arrays to the controller....So, from now on when thinking arrays, think of each array in series, then those arrays paralleled to your controller/controllers....Based on your controller and the size of your panels, you may be only able to parallel your panels in each array, like me....Where IF that is the case, then you will really have to worry that you will have nuff voltage at the controllers to push those sweet amps into your battery....And THAT is where large gauge wiring, short runs, and minimum number of connections really become important. That said, now, go a step further and consider possible shading in your travels.....As already stated, arrays in parallel or single panels in parallel suffer much less power loss than those in series....So that is a plus 1 for parallel, huh? But arrays or single panels in series offer much higher volts to push the amps to the controller, so that's a plus 1 for series. And seeing as how you will have 24V @ 15.6A with 3 pairs of 2, where each of the 2 are connected in series, And 36V @ 10.4A with 2 pairs of 3....Where each of the 3 are connected in series, Then either way you are good to go and it will work well with your install distances and your controller, huh?...Yep, so why select one over the other? Why select three 2 panel arrays with the 3 panels in each array connected in series, over two with 3 panel arrays connected in series? That answer really only boils down to your expectations of shading....So if you expect frequent partial shading, then you will get quicker charges with 3 pairs of 2, because you will have more arrays connected in parallel than if you linked it all up with just two 3 panel arrays in parallel....Fall is in full swing here where I am at, and those huge trees of mine are dropping leaves like a hail storm, but no worries later this winter when I will be way out there in the desert....So shading is situational for all of us, but at least know what to expect after your choice. Enjoy your new system!
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Post by cottagecamper on Nov 15, 2018 3:23:16 GMT
Great, thanks. So let me summarize what I think I should do given all y'all's advice plus my circumstances:
I will make 2 strings of 3 panels in series (12v x 3 = 36v@5.2a) and connect the 2 strings together in parallel (making 36v @10.43a).
I'm in Florida and I'm not too concerned right now about the shade factor, but I will be putting one string along one pitch of the roof of my Tiny House, the other string on the other side of the pitch. The roof is nearly flat, but both strings will not be at the same angle of the sun at any time.
Each PV panel is pre-wired with a 10/12 MC4 on a 1.5 ft lead wire from the diode box. I am laying the panels end to end on the roof of the Tiny House. The furthest panel will connect its 1.5ft Positive lead to the middle panel's Negative 1.5ft lead. (short wire to short wire) And the center panel will connect its other lead to a 4ft extension to the front panel's lead. (I would think the 4ft extension will be ok at 10AWG, yes?) But the furthest panel's Negative lead will have to run 15ft to the front of the house where it will be connected into the MC4 branch in parallel to the other string. Q: Does that 15ft wire need to be bigger gauge? (It will be carrying 5.2a @36v, right?)
Once connected in parallel at the front of the TH, the wires will drop down from the roof into the house to the controller (12 more feet down). Two questions here: Do I need a combiner box at this connection or just the double Y MC4 branches? Does that 12 ft wire need to be a bigger gauge? (That will be carrying 10.4a @36v)
I really want to nail this down & order the lengths/AWG & MC4s so I can hook these babies up over Thanksgiving week.
Again, Thanks in advance.
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Post by swampmonster on Nov 15, 2018 4:17:07 GMT
Well, now that you supplied the extra info....you are screwed...Not totally, but kinda sorta.
Experience shows that if panels and / or panel arrays face different exposures, then each exposure is best connected to it's own controller.
OTHERWISE the total of all arrays will be diminished to the array with least exposure when connected to one controller.
In your case it is not a game stopper, but your total system will suffer somewhat....There will, at high noon be a period of best high average from both arrays, but as the sun travels it's arc, the panel array more orientated with the sun will deliver better power than the array not so well oriented, but the total will be dragged down lots by the other array...Then, depending on the orientation of your house to the suns arc the other array will be top dog but be dragged down by the opposite array...No problem if each array is connected to it's own controller, but on one controller the lesser array will have a big effect on the other.
So, what may happened, depending on you roof design and alignment with the sun's arc, is half your total system will deliver great power, while the other half doesn't, but the controller will see it as a lesser power level of both arrays...Then as the sun hits noon the controller cheers, but as the sun travels it's arc, the controller again will sag.
I know it's kinda questionable and you wanna say BS because ok, there will a once peak and twice wane everyday, but what you are missing is the fact when one array is in the wane, it will effect the other array output AT the controller....YEP.
With two controllers where one is assigned to each array, each will deliver it's full potential independent of the other.
Not saying you need two controllers, but suggesting you MAY want to buy that 8th Panel you are already equipped to support to help mitigate those losses....Keep in mind the losses I described may be very minimal, or extreme depending on roof pitch and angle of each array, and house orientation to sun's arc.
As far as cable sizing, you already have the info available to construct a system that will serve within published "Standard Acceptable Losses" of = or less than 3 volts from panels to controller, but you can reduce loses much more with larger cable and maybe should also reduce # of connections.
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Post by bupkis on Nov 15, 2018 13:17:58 GMT
Great configuration, 10g is ample for all wiring from panel to controller, ~1% or .5v. You input voltage will near 50v.
One of the great things about mppt controlls is they find the peak power of panels, especially those paralleled together
Edit: the branch connectors take place of a combiner box.
Edit 2: consider some sort of cutoff switch near the controller cuz you need to disconnect the panels before disconnecting the battery, the reverse is true for hook up, first you connect the controller and then the panels. You can always unscrew one of the panel wires but a cutoff is easier.
Tray cable (battery to controller) 6g or larger, fused >45A, 60A fuse/circuit breaker would be appropriate @ the battery bank.
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Post by cottagecamper on Nov 15, 2018 22:31:07 GMT
Well, now that you supplied the extra info....you are screwed...Not totally, but kinda sorta. Experience shows that if panels and / or panel arrays face different exposures, then each exposure is best connected to it's own controller. OTHERWISE the total of all arrays will be diminished to the array with least exposure when connected to one controller. In your case it is not a game stopper, but your total system will suffer somewhat....There will, at high noon be a period of best high average from both arrays, but as the sun travels it's arc, the panel array more orientated with the sun will deliver better power than the array not so well oriented, but the total will be dragged down lots by the other array...Then, depending on the orientation of your house to the suns arc the other array will be top dog but be dragged down by the opposite array...No problem if each array is connected to it's own controller, but on one controller the lesser array will have a big effect on the other. So, what may happened, depending on you roof design and alignment with the sun's arc, is half your total system will deliver great power, while the other half doesn't, but the controller will see it as a lesser power level of both arrays...Then as the sun hits noon the controller cheers, but as the sun travels it's arc, the controller again will sag. I know it's kinda questionable and you wanna say BS because ok, there will a once peak and twice wane everyday, but what you are missing is the fact when one array is in the wane, it will effect the other array output AT the controller....YEP. With two controllers where one is assigned to each array, each will deliver it's full potential independent of the other. Not saying you need two controllers, but suggesting you MAY want to buy that 8th Panel you are already equipped to support to help mitigate those losses....Keep in mind the losses I described may be very minimal, or extreme depending on roof pitch and angle of each array, and house orientation to sun's arc. As far as cable sizing, you already have the info available to construct a system that will serve within published "Standard Acceptable Losses" of = or less than 3 volts from panels to controller, but you can reduce loses much more with larger cable and maybe should also reduce # of connections. Thanks, swampmonster. True I didn't lay out all the info upfront cuz there's just so many details & I didn't want to overwhelm anybody. Good to know about the reduced output due to the differing angles. The house currently points into the south, (gable peak pointing north to south) so the sun's arc comes up on the east side of the roof pitch, peaks at the gable & sets on the same angle of the other. So yes, I think I will be getting the 8th panel after Christmas.
Once I do install #7 & #8, I will have 4 in series per string. Can I still use #10AWG? (48v@5.2a) per string.
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Post by tattoo on Nov 15, 2018 22:46:59 GMT
Once I do install #7 & #8, I will have 4 in series per string. Can I still use #10AWG? (48v@5.2a) per string.
Yes sir you can run the same size wire that is on the panels right now all the way to your CC..... That's the same set up I have.... It's been doing just fine for two years...
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Post by cottagecamper on Nov 15, 2018 22:57:26 GMT
Great configuration, 10g is ample for all wiring from panel to controller, ~1% or .5v. You input voltage will near 50v. One of the great things about mppt controlls is they find the peak power of panels, especially those paralleled together Edit: the branch connectors take place of a combiner box. Edit 2: consider some sort of cutoff switch near the controller cuz you need to disconnect the panels before disconnecting the battery, the reverse is true for hook up, first you connect the controller and then the panels. You can always unscrew one of the panel wires but a cutoff is easier. Tray cable (battery to controller) 6g or larger, fused >45A, 60A fuse/circuit breaker would be appropriate @ the battery bank. Thanks, bupkis. I do intend to put a cut off disconnect before the battery. I already have it in my box of supplies. It's a mega size for a marine application. Should do the trick.
Also, yes, thanks for the clarification re: the Tray Cable. I will indeed use 6g for that and fuse it at 60amp.
I hope to eventually have 400 ah of battery bank, but with AGMs running $285 each, that won't be til the new year rolls around.
I also have a 2000watt pure sine wave inverter in my box of tricks. I have a 300amp ANL fuse to connect that so I won't zap anything out. But I have a new question about inverters. If I hook up a 2000 watt inverter and turn it on, does it start drawing out power immediately or as I would imagine it adjusts its draw based on its load at any time during the day. In other words, if I only draw max about 800 watts at any one time (besides peaking) would it be better for me to get a smaller inverter and "save" the battery power?
And once I get the 7th & 8th panels hooked up (will result in 2 strings of 4 each) would I then need to bump up my wire size? or, becuz it should still be 48v@10.4a that I can still run the 10g wire?
I really appreciate knowing the branch connectors take the place of the combiner box. very glad.
You guys have been great. And patient with me that I have so many questions. Thanks again.
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Post by tattoo on Nov 15, 2018 23:58:08 GMT
I also have a 2000watt pure sine wave inverter in my box of tricks. I have a 300amp ANL fuse to connect that so I won't zap anything out. But I have a new question about inverters. If I hook up a 2000 watt inverter and turn it on, does it start drawing out power immediately or as I would imagine it adjusts its draw based on its load at any time during the day. In other words, if I only draw max about 800 watts at any one time (besides peaking) would it be better for me to get a smaller inverter and "save" the battery power?
And once I get the 7th & 8th panels hooked up (will result in 2 strings of 4 each) would I then need to bump up my wire size? or, becuz it should still be 48v@10.4a that I can still run the 10g wire? Yes your inverter uses power when it's on even when there is no draw..... That's why I have a 2000w and a 500w inverter..... The 500w runs 24/7 and the 2000w inverter is for things like table saws etc.... You know for larger things.....
What kind of 10g wire are you talking about wanting to use? Are you talking about the wire that comes on the panels? Or solid or braided wire? I figured I had better ask...
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Post by swampmonster on Nov 16, 2018 0:02:52 GMT
Great configuration, 10g is ample for all wiring from panel to controller, ~1% or .5v. You input voltage will near 50v. One of the great things about mppt controlls is they find the peak power of panels, especially those paralleled together Edit: the branch connectors take place of a combiner box. Edit 2: consider some sort of cutoff switch near the controller cuz you need to disconnect the panels before disconnecting the battery, the reverse is true for hook up, first you connect the controller and then the panels. You can always unscrew one of the panel wires but a cutoff is easier. Tray cable (battery to controller) 6g or larger, fused >45A, 60A fuse/circuit breaker would be appropriate @ the battery bank. Thanks, bupkis. I do intend to put a cut off disconnect before the battery. I already have it in my box of supplies. It's a mega size for a marine application. Should do the trick.
Also, yes, thanks for the clarification re: the Tray Cable. I will indeed use 6g for that and fuse it at 60amp.
I hope to eventually have 400 ah of battery bank, but with AGMs running $285 each, that won't be til the new year rolls around.
I also have a 2000watt pure sine wave inverter in my box of tricks. I have a 300amp ANL fuse to connect that so I won't zap anything out. But I have a new question about inverters. If I hook up a 2000 watt inverter and turn it on, does it start drawing out power immediately or as I would imagine it adjusts its draw based on its load at any time during the day. In other words, if I only draw max about 800 watts at any one time (besides peaking) would it be better for me to get a smaller inverter and "save" the battery power?
And once I get the 7th & 8th panels hooked up (will result in 2 strings of 4 each) would I then need to bump up my wire size? or, becuz it should still be 48v@10.4a that I can still run the 10g wire?
I really appreciate knowing the branch connectors take the place of the combiner box. very glad.
You guys have been great. And patient with me that I have so many questions. Thanks again.
Base the selection of your inverter on your estimation of peak loads you can expect...Peak, even if it is not daily might be your best selection depending on budget. However inverters of any size have different Idle draws, where some consume very little power when left on with no 120V loads....Idle draw is the power required to keep the inverter fired up even when it is not providing inverted power....Often the inverter maker leaves this spec out of their product description because it is spec item they don't want to wave in your face when shopping inverters....Many better inverters have a power switch position that allows you to place the inverter on, but in low idle power draw where the invertor will wake up only if it senses certain levels of 120V load....Mine is fixed at 40 watts load before it will wake up...And when asleep in standby it uses VERY little power.....But in my experience all inverters consume some level of battery power whenever they are turned on.
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Post by cottagecamper on Nov 16, 2018 0:24:22 GMT
What kind of 10g wire are you talking about wanting to use? Are you talking about the wire that comes on the panels? Or solid or braided wire? I figured I had better ask...
Ya the wire is 10g solar. Has MC4 connectors already. (the pieces I already had purchased) so I'll get more of same for the longer runs I'll need as I had described about my planned array.
Thanks for the clarification...you never know!
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Post by cottagecamper on Nov 16, 2018 0:38:21 GMT
…
I also have a 2000watt pure sine wave inverter in my box of tricks. I have a 300amp ANL fuse to connect that so I won't zap anything out. But I have a new question about inverters. If I hook up a 2000 watt inverter and turn it on, does it start drawing out power immediately or as I would imagine it adjusts its draw based on its load at any time during the day. In other words, if I only draw max about 800 watts at any one time (besides peaking) would it be better for me to get a smaller inverter and "save" the battery power?
You guys have been great. And patient with me that I have so many questions. Thanks again.
Base the selection of your inverter on your estimation of peak loads you can expect...Peak, even if it is not daily might be your best selection depending on budget. However inverters of any size have different Idle draws, where some consume very little power when left on with no 120V loads....Idle draw is the power required to keep the inverter fired up even when it is not providing inverted power....Often the inverter maker leaves this spec out of their product description because it is spec item they don't want to wave in your face when shopping inverters....Many better inverters have a power switch position that allows you to place the inverter on, but in low idle power draw where the invertor will wake up only if it senses certain levels of 120V load....Mine is fixed at 40 watts load before it will wake up...And when asleep in standby it uses VERY little power.....But in my experience all inverters consume some level of battery power whenever they are turned on. Thanks, Swampmonster. I already purchased the 2000 watt pure sine wave inverter. It was for my cabin I never finished... so I have all kinds of solar stuff I'm working into this array. I'll reveal it in posts as we move along in the coming months...I'm only getting started and I've forgotten most of what I had already figured out. LOL.
That said, I do understand the "idle power draw" any appliance will use when "on" but my specific ignorance is about how the inverter provides power to something plugged into it. For example, I will have the inverter hooked up to the 120v Romex which will have 4 outlets on the run. If I plug in a coffee pot that uses say 100watts, how much will I be drawing off my batteries? a bit over 100watts? (coffee pot plus conversion loss, etc adjusted for efficiency?) OR the full 2000 watts that the inverter is capable of? In other words, does the inverter adjust its output based on need?
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Post by tattoo on Nov 16, 2018 1:09:17 GMT
Ya the wire is 10g solar. Has MC4 connectors already. (the pieces I already had purchased) so I'll get more of same for the longer runs I'll need as I had described about my planned array.
Thanks for the clarification...you never know!
Yes those wires will work just fine with 4 100a panels in series...... Like I said that's what I'm using with my system...
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Post by playersz28 on Nov 16, 2018 2:06:56 GMT
That said, I do understand the "idle power draw" any appliance will use when "on" but my specific ignorance is about how the inverter provides power to something plugged into it. For example, I will have the inverter hooked up to the 120v Romex which will have 4 outlets on the run. If I plug in a coffee pot that uses say 100watts, how much will I be drawing off my batteries? a bit over 100watts? (coffee pot plus conversion loss, etc adjusted for efficiency?) OR the full 2000 watts that the inverter is capable of? In other words, does the inverter adjust its output based on need?
The draw on the batteries caused by the inverter will depend on how many watts of AC power it is supplying. If you have a 100w load attached and turned on then for 100% efficient conversion it's drawing 8.3A off the batteries. The 100% doesn't exist though so maybe 85-90% with a good inverter (PSW is better than MSW). The easy way to avoid the standby usage from the inverter is to simply turn it off when you don't need the AC power. I have a 2000w PSW with a remote switch and even though it has a small standby draw I just turn it on when I need it and turn it off when I don't.
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Post by swampmonster on Nov 16, 2018 2:44:53 GMT
Base the selection of your inverter on your estimation of peak loads you can expect...Peak, even if it is not daily might be your best selection depending on budget. However inverters of any size have different Idle draws, where some consume very little power when left on with no 120V loads....Idle draw is the power required to keep the inverter fired up even when it is not providing inverted power....Often the inverter maker leaves this spec out of their product description because it is spec item they don't want to wave in your face when shopping inverters....Many better inverters have a power switch position that allows you to place the inverter on, but in low idle power draw where the invertor will wake up only if it senses certain levels of 120V load....Mine is fixed at 40 watts load before it will wake up...And when asleep in standby it uses VERY little power.....But in my experience all inverters consume some level of battery power whenever they are turned on. Thanks, Swampmonster. I already purchased the 2000 watt pure sine wave inverter. It was for my cabin I never finished... so I have all kinds of solar stuff I'm working into this array. I'll reveal it in posts as we move along in the coming months...I'm only getting started and I've forgotten most of what I had already figured out. LOL.
That said, I do understand the "idle power draw" any appliance will use when "on" but my specific ignorance is about how the inverter provides power to something plugged into it. For example, I will have the inverter hooked up to the 120v Romex which will have 4 outlets on the run. If I plug in a coffee pot that uses say 100watts, how much will I be drawing off my batteries? a bit over 100watts? (coffee pot plus conversion loss, etc adjusted for efficiency?) OR the full 2000 watts that the inverter is capable of? In other words, does the inverter adjust its output based on need?
An A/C load will draw it's full load from the inverter. If that load is 100 watts, the load will draw 100 watts. The battery will however experience the full load plus the losses of efficiency consumed by the inverter + the power required to operate the inverter..... So, in the case of any load, the load will get it's full load up to the limits of the inverter, but the battery will suffer extra losses due to inverter losses plus inverter operating requirements....Sometimes this factor alone might help you select the best inverter.
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