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Post by Deleted on Apr 18, 2020 6:24:31 GMT
A towel is always your friend when dealing with solar!π I just turn off the DC rated mcb to the panels, Midnite told me to install one so I did. DC mcb to panels? I wondered about the 15 amp fuse, part of a trio of blade fuses, I can't be sure it is sited twixt panels and controller, though it seems probable........ but if I remove the fuse, does this act in the same way as an isolator switch. btw there is an isolator switch in the area, it isolates the radio and the Webasto, not sure about anything else.
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Post by bodger on Apr 18, 2020 6:53:58 GMT
OK, challenge ahead: my electrics leave a lot to the imagination, I now have three x 135ah new agm domestic batteries at the stern, two older agms at bow on a separate line, these are used to charge electronics. The existing solar works in bright sunlight, but I have to use engine to charge them if fridge is ON and it is cloudy. I now have to consider swapping existing solar set up for my new one, a two panel x 275W panels with 40amp controller. I intend to replace existing panels, wiring and controller, I am not sure where to start! Wouldn't your best plan be to leave the existing solar panels in situ and to increase the total generating capacity by installing the new ones on any sufficiently large vertical interior surface that you normally stand or sit facing away from ? you forgot to mention the ceiling !
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Post by Telemachus on Apr 18, 2020 8:52:50 GMT
I just turn off the DC rated mcb to the panels, Midnite told me to install one so I did. DC mcb to panels? I wondered about the 15 amp fuse, part of a trio of blade fuses, I can't be sure it is sited twixt panels and controller, though it seems probable........ but if I remove the fuse, does this act in the same way as an isolator switch. btw there is an isolator switch in the area, it isolates the radio and the Webasto, not sure about anything else. You donβt need an isolator between panels and controller, although it might be convenient to have some sort of means of disconnecting panels. You donβt need a fuse between controller and panels, although again that can be a convenient way to disconnect the panels as you suggest. You only need fusing of individual panels with a multi-panel configuration where a short circuit at a panel could sap the current of all the other panels and overheat the panelβs local wiring. You donβt want an isolator between controller and batteries as itβs too easy to turn off accidentally. But you do need a fuse between batteries and controller, located very near the batteries, since batteries are a potential source of extremely high current in the event of a short circuit.
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Post by Jim on Apr 18, 2020 9:20:32 GMT
DC mcb to panels? I wondered about the 15 amp fuse, part of a trio of blade fuses, I can't be sure it is sited twixt panels and controller, though it seems probable........ but if I remove the fuse, does this act in the same way as an isolator switch. btw there is an isolator switch in the area, it isolates the radio and the Webasto, not sure about anything else. You donβt need an isolator between panels and controller, although it might be convenient to have some sort of means of disconnecting panels. You donβt need a fuse between controller and panels, although again that can be a convenient way to disconnect the panels as you suggest. You only need fusing of individual panels with a multi-panel configuration where a short circuit at a panel could sap the current of all the other panels and overheat the panelβs local wiring. You donβt want an isolator between controller and batteries as itβs too easy to turn off accidentally. But you do need a fuse between batteries and controller, located very near the batteries, since batteries are a potential source of extremely high current in the event of a short circuit. The last bit, shouldn't the controller to battery wire go to the "dead" side of the battery isolation switch? AIUI the only thing to remain live with the isolator off is a fused bilge pump? This is why I put a switch between panel and controller (post 2). Just have to remember to switch them off in the right order. panel switch first.
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Post by Telemachus on Apr 18, 2020 9:53:23 GMT
You donβt need an isolator between panels and controller, although it might be convenient to have some sort of means of disconnecting panels. You donβt need a fuse between controller and panels, although again that can be a convenient way to disconnect the panels as you suggest. You only need fusing of individual panels with a multi-panel configuration where a short circuit at a panel could sap the current of all the other panels and overheat the panelβs local wiring. You donβt want an isolator between controller and batteries as itβs too easy to turn off accidentally. But you do need a fuse between batteries and controller, located very near the batteries, since batteries are a potential source of extremely high current in the event of a short circuit. The last bit, shouldn't the controller to battery wire go to the "dead" side of the battery isolation switch? AIUI the only thing to remain live with the isolator off is a fused bilge pump? This is why I put a switch between panel and controller (post 2). Just have to remember to switch them off in the right order. panel switch first. No, there is a list of items in the BSS which can be connected direct to the batteries. Consider a battery charger - if the charger is connected boat-side, not only will it not trickle charge the batteries with the isolator off, it will keep all the boat services live. Same with solar (if you forget to isolate the panels.). Humans make mistakes and at some point, you will turn off the isolator with the panels live, it is just a matter of time. This is the text from the BSS, giving a list of things that can be connected directly to the battery (via a fuse): Identify any d.c. electrical circuits bypassing the battery isolator. Check that any electrical circuits bypassing the battery isolator supply the following equipment: β’ automatic bilge pumps; β’ security alarms (including marine radios); β’ fire pumps; β’ electronic navigation equipment with memories; β’ any other equipment where the manufacturerβs instructions indicate or specifically require direct connection to a battery, such as dieselβfired central heating boilers; β’ battery charger outputs; β’ inverters or combination inverter/chargers; β’ solar panels and wind turbines. Check electrical circuits supplying any equipment on the specified list, and which bypass a battery isolator, for the presence of a fuse or circuitβbreaker, where the circuit can be seen.
All d.c. electrical circuits must pass through a battery isolator, except those which feed equipment requiring a continuous supply which must be protected by a suitable fuse or circuitβ breaker.
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DIY SOLAR
Apr 18, 2020 10:00:58 GMT
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Post by Jim on Apr 18, 2020 10:00:58 GMT
The last bit, shouldn't the controller to battery wire go to the "dead" side of the battery isolation switch? AIUI the only thing to remain live with the isolator off is a fused bilge pump? This is why I put a switch between panel and controller (post 2). Just have to remember to switch them off in the right order. panel switch first.Β No, there is a list of items in the BSS which can be connected direct to the batteries. Consider a battery charger - if the charger is connected boat-side, not only will it not trickle charge the batteries with the isolator off, it will keep all the boat services live. Same with solar (if you forget to isolate the panels.). Humans make mistakes and at some point, you will turn off the isolator with the panels live, it is just a matter of time. This is the text from the BSS, giving a list of things that can be connected directly to the battery (via a fuse): Identify any d.c. electrical circuits bypassing the battery isolator. Check that any electrical circuits bypassing the battery isolator supply the following equipment: β’ automatic bilge pumps; β’ security alarms (including marine radios); β’ fire pumps; β’ electronic navigation equipment with memories; β’ any other equipment where the manufacturerβs instructions indicate or specifically require direct connection to a battery, such as dieselβfired central heating boilers; β’ battery charger outputs; β’ inverters or combination inverter/chargers; β’ solar panels and wind turbines. Check electrical circuits supplying any equipment on the specified list, and which bypass a battery isolator, for the presence of a fuse or circuitβbreaker, where the circuit can be seen.
All d.c. electrical circuits must pass through a battery isolator, except those which feed equipment requiring a continuous supply which must be protected by a suitable fuse or circuitβ breaker.OK, I see. I'll move the panel feed to the live side of the isolator or the positive bus bar then.
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Post by peterboat on Apr 18, 2020 13:59:32 GMT
I just turn off the DC rated mcb to the panels, Midnite told me to install one so I did. DC mcb to panels? I wondered about the 15 amp fuse, part of a trio of blade fuses, I can't be sure it is sited twixt panels and controller, though it seems probable........ but if I remove the fuse, does this act in the same way as an isolator switch. btw there is an isolator switch in the area, it isolates the radio and the Webasto, not sure about anything else. I have a midnite controller which has a 5 year warranty and to keep the warranty I have to have an MCB between the panels and the controller plus one between the controller and batteries here is a Midnite diagram for installation
Classic Simple Flow Diagram - Midnite Solar www.midnitesolar.com βΊ pdfs βΊ classic_simple_flow_dia... PDF
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Post by Telemachus on Apr 18, 2020 14:05:48 GMT
DC mcb to panels? I wondered about the 15 amp fuse, part of a trio of blade fuses, I can't be sure it is sited twixt panels and controller, though it seems probable........ but if I remove the fuse, does this act in the same way as an isolator switch. btw there is an isolator switch in the area, it isolates the radio and the Webasto, not sure about anything else. I have a midnite controller which has a 5 year warranty and to keep the warranty I have to have an MCB between the panels and the controller plus one between the controller and batteries here is a Midnite diagram for installation
Classic Simple Flow Diagram - Midnite Solar www.midnitesolar.com βΊ pdfs βΊ classic_simple_flow_dia... PDF What purpose does a breaker between solar and controller serve?
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Post by peterboat on Apr 18, 2020 15:56:06 GMT
I have a midnite controller which has a 5 year warranty and to keep the warranty I have to have an MCB between the panels and the controller plus one between the controller and batteries here is a Midnite diagram for installation
Classic Simple Flow Diagram - Midnite Solar www.midnitesolar.com βΊ pdfs βΊ classic_simple_flow_dia... PDF What purpose does a breaker between solar and controller serve? Ask Midnite they are the experts after all and they as you can see from the link put one in, maybe its for a short circuit over amps coming down the lines and it protects the controller other strings of panels? They are market leaders in the USA and they would not do it without good reason Actually I do know I have just googled it and here is the link its because the USA has decided to make regulations for safe solar installations
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Post by Telemachus on Apr 18, 2020 19:31:31 GMT
What purpose does a breaker between solar and controller serve? Ask Midnite they are the experts after all and they as you can see from the link put one in, maybe its for a short circuit over amps coming down the lines and it protects the controller other strings of panels? They are market leaders in the USA and they would not do it without good reason Actually I do know I have just googled it and here is the link its because the USA has decided to make regulations for safe solar installations
I think the document, for all its wiffle waffle, explains it in as much as it is designed for housing and building where you could have a very large number of panels. I only skimmed it but it seems that a βbreakerβ is just a switch, rather than an over current device, and the purpose of the switch is to isolate the potentially dangerously high voltages coming from a series string. Iβd agree that if your string voltage is over say 80v then an isolator switch is a good idea for reasons of electric shock protection. But if you just have a couple of panels, or panels in series/parallel and the max open circuit voltage is say 50v, there isnβt much point. There is certainly no point in putting a fuse or other over-current device in the main feed to the controller because the laws of physics says that a bunch of panels canβt suddenly start producing way over their rated output. Moreβs the pity!
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Post by peterboat on Apr 19, 2020 16:56:03 GMT
Ask Midnite they are the experts after all and they as you can see from the link put one in, maybe its for a short circuit over amps coming down the lines and it protects the controller other strings of panels? They are market leaders in the USA and they would not do it without good reason Actually I do know I have just googled it and here is the link its because the USA has decided to make regulations for safe solar installations
I think the document, for all its wiffle waffle, explains it in as much as it is designed for housing and building where you could have a very large number of panels. I only skimmed it but it seems that a βbreakerβ is just a switch, rather than an over current device, and the purpose of the switch is to isolate the potentially dangerously high voltages coming from a series string. Iβd agree that if your string voltage is over say 80v then an isolator switch is a good idea for reasons of electric shock protection. But if you just have a couple of panels, or panels in series/parallel and the max open circuit voltage is say 50v, there isnβt much point. There is certainly no point in putting a fuse or other over-current device in the main feed to the controller because the laws of physics says that a bunch of panels canβt suddenly start producing way over their rated output. Moreβs the pity! Its used for RVs as well, They do use MCBs or midnite do anyway. The problem is that 2 panels now can be over 80 volts as we use more of the big panels on boats, mine is running at close to 200 volts and a fair few amps which is why its so effective on the immersion heater, my water is now to hot to run on your hand, the system is safe as the immersion is in the heat store so if the water gets to hot it turns on the central heating pump
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Post by Telemachus on Apr 19, 2020 17:14:41 GMT
I think the document, for all its wiffle waffle, explains it in as much as it is designed for housing and building where you could have a very large number of panels. I only skimmed it but it seems that a βbreakerβ is just a switch, rather than an over current device, and the purpose of the switch is to isolate the potentially dangerously high voltages coming from a series string. Iβd agree that if your string voltage is over say 80v then an isolator switch is a good idea for reasons of electric shock protection. But if you just have a couple of panels, or panels in series/parallel and the max open circuit voltage is say 50v, there isnβt much point. There is certainly no point in putting a fuse or other over-current device in the main feed to the controller because the laws of physics says that a bunch of panels canβt suddenly start producing way over their rated output. Moreβs the pity! Its used for RVs as well, They do use MCBs or midnite do anyway. The problem is that 2 panels now can be over 80 volts as we use more of the big panels on boats, mine is running at close to 200 volts and a fair few amps which is why its so effective on the immersion heater, my water is now to hot to run on your hand, the system is safe as the immersion is in the heat store so if the water gets to hot it turns on the central heating pump Having an overcurrent device is nevertheless completely pointless. The panels can produce a certain maximum current at max power, which the wiring should be able to cope with. The short circuit current of the panels is only a bit more. Not really enough for an MCB to differentiate between the normal state and the short circuit state. Yes the voltages can be very high (hence the need for a switch) but that is nothing to do with an overcurrent. It is not like a battery which, under fault conditions, could produce very high currents. Unless you can explain how a significant overcurrent could possibly arise I shall continue to consider an overcurrent device completely pointless despite what some yanks might say.
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Deleted
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Post by Deleted on Apr 21, 2020 8:03:44 GMT
sorry, what I should have explained is that I don't know what "mcb" stands for [weep]
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Post by JohnV on Apr 21, 2020 8:04:27 GMT
Miniature Circuit Breaker
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Post by Jim on Apr 21, 2020 8:17:39 GMT
Miniature Circuit Breaker A push button to reset fuse.
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