New to solar, need fusing information

DenyseDenyse Registered Users Posts: 8
I will be setting up 3-100 watt (Renogy) panels and will be using a 1000w/2000w inverter. I can find no information on how to's on what size fuses/fuse holder/fuse box to use--both on the panel to controller end and between the battery(s) and inverter. I am not sure of what ah battery(s) I will be using at this time.

Thanks

Comments

  • PhotowhitPhotowhit Solar Expert Posts: 4,996 ✭✭✭✭
    Re: New to solar, need fusing information

    3 or more panels in parallel need to be combined, you can search for combiner boxes, and find videos and other info, the panels will have a series fuse rating, likely 15 amps, so each panel will have a 15 amp fuse or breaker, then combined into a single line to your charge controller. I often suggest a DC disconnect box as an all propose box if your panels are near your charge controller, and batteries. You can search the Northern Arizona Wind and Sun site (NAWS our sponsor) for 'Mini DC disconnect' and 'combiner box'. The Combiner box is located near the panels and the DC disconnect box would include a main breaker from your battery to your inverter and a smaller breakers for your incoming(if you want one) and out going current to and from your charge controller.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: New to solar, need fusing information

    Welcome to the forum.

    I think you better back up and determine what size battery bank you need before you commit yourself to any panels, controller, and wiring. 300 Watts of PV is not going to support much battery; maybe a couple of 220 Amp hour 6 Volts on a 12 Volt system. That really needs to be determined first.

    And there should be a fuse or breaker between the charge controller and the batteries as well as between the batteries and the inverter. These two are the most important. Whether or not there are any per-string fuses/breakers depends on the final array configuration which depends on how much PV is needed to recharge the batteries selected.
  • ZakarumeZakarume Solar Expert Posts: 143 ✭✭
    Re: New to solar, need fusing information

    Listen to Cariboocoot and Photwhit they have helped me out alot. You might want to think about switching to a 24v system instead of a 12v. But if not, you need a combiner box. Here is the one i am using http://www.solar-electric.com/mnpv6.html. And for the fuse between inverter and batteries. http://www.amazon.com/Scoshe-EWFH-Single-Fuse-Holder/dp/B000KIR8M0/ref=sr_1_2?ie=UTF8&qid=1416490493&sr=8-2&keywords=150+amp+fuse
    1460 Watts Solar @24v. 675 AH Battery Bank using 12 6v Trojan T-105. 1 Midnite Classic 150. 1500 Watt 24v Samlex Pure Sine Inverter
  • DenyseDenyse Registered Users Posts: 8
    Re: New to solar, need fusing information

    Thank you for this. One would think that the company selling the product would provide more information than they do.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: New to solar, need fusing information
    Denyse wrote: »
    Thank you for this. One would think that the company selling the product would provide more information than they do.

    That depends on the company. All the good ones have documentation available on-line before the purchase: installation manuals. They go into detail about what wire and fuse/breaker sizes to be used under what circumstances. It is a good idea to read up on what you are about to undertake before buying any equipment as it may affect your choices. If you can't read up on it, don't expect best results.
  • DenyseDenyse Registered Users Posts: 8
    Re: New to solar, need fusing information

    Yes, I am somewhat working backwards and working off general information as to minimal RV "needs". These panels will be going on a RV (for now) and right at the moment I have no idea what I might be powering in total other than the 12v lighting and a built in radio. The RV is basically a project I will be working on although I am camping/living in it currently and the most power resources I would need to plan for in addition to the previous would be for maybe a tv and a coffee pot. I'm sticking with the bare minimum. The refrig runs off propane. I won't be using a microwave or other appliances of that sort. I will also have a generator for higher consumption needs.

    I am currently using a 150 watt (Renogy) panel to charge 4-35ah batteries which I am only using to charge / power my computer and 1 light with a 13-watt CFL bulb. That basically covers my important "needs" and will remain separate from the other.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: New to solar, need fusing information

    You might want to rethink the coffee pot: it can use as much power as a microwave, and perhaps more in terms of Watt hours. Generally any heating element is in the 1kW range.

    Otherwise if your limit is being able to fit only three of these 100 Watt panels, you're kind of hemmed in. You can either restrict the battery bank to what they will recharge properly (about 5 Amps per panel on those as I recall - 15 Amps total) and accept the available power limit, or you can opt for generator charging of a larger bank and use the panels to extend the run time/finish charging it. As with everything either choice is a compromise.
  • zonebluezoneblue Solar Expert Posts: 1,218 ✭✭✭✭
    Re: New to solar, need fusing information

    BTW ANL fuses dont really belong in RE setups. Midnites Carling and CBi breakers are the best bang for buck, and 10 times safer. If abused ANL fuses can explode quite extensively. Its all about interupt capacity when your dealing with batteries with low internal resistance.

    Short answer: Midnite Solar. All the products and documentation you could ever need.
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
    http://zoneblue.org/cms/page.php?view=off-grid-solar


  • DenyseDenyse Registered Users Posts: 8
    Re: New to solar, need fusing information

    Yeah, the coffee pot was just thrown in but not a necessity. I have a campfire and stove for that part. Restricting the battery bank to what the panels are capable of is the point I was actually working from--a point from which it is hard to get information and I understand that it is backwards. This is for the learning experience and I learn better from the end point backwards. Someday in the future, when I can afford to build a home on the land I am camped on, solar is the route I wish to go so I want to work my way through the process on a limited scale and get an understanding of the capabilities and limitations.I fully realize there are "inputs" one needs to get proper information. I have a friend that lives completely off grid so I have a basic understanding of that part. Thank you for your assistance.
  • DenyseDenyse Registered Users Posts: 8
    Re: New to solar, need fusing information

    I'd rather go the safest regardless of cost. Thanks.
  • PhotowhitPhotowhit Solar Expert Posts: 4,996 ✭✭✭✭
    Re: New to solar, need fusing information
    zoneblue wrote: »
    BTW ANL fuses dont really belong in RE setups. Midnites Carling and CBi breakers are the best bang for buck, and 10 times safer. If abused ANL fuses can explode quite extensively.

    I don't know about safer, a fuse will interrupt the flow of current, but breakers are much nicer, since they can be reset. I'm not sure how an ANL fuse would explode. FWIW - My Prosine and Exeltech inverters both have fuses inside. The Prosine has a Littelfuse Mega 125, a fuse used in autos/trucks.

    I like the idea of having a fuse in the battery box incase of a short there, this would be behind a breaker at the Power center, though I don't have one. I think some here have used the marine button fuses mounted on the battery.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • Mountain DonMountain Don Solar Expert Posts: 494 ✭✭✭
    Re: New to solar, need fusing information

    Cheapy ANL's have been known to blow casing pieces all over the place. I believe the preferred fuse between the battery + and the inverter is a type T. Very quick blow and totally encased so there is no flame arc when it blows. Very safe even right there beside the battery.
    Northern NM, 624 watts PV, The Kid CC, GC-2 batteries @ 24 VDC, Outback VFX3524M
  • DenyseDenyse Registered Users Posts: 8
    Re: New to solar, need fusing information

    Thank you for the info.
  • DenyseDenyse Registered Users Posts: 8
    Re: New to solar, need fusing information

    It seems that a breaker would be the most preferable option then.
  • zonebluezoneblue Solar Expert Posts: 1,218 ✭✭✭✭
    Re: New to solar, need fusing information

    More about AIC (ampere interupt capacity).

    "The interrupt rating for a fuse or breaker is the fault current it is capable of interrupting. Every circuit breaker has a time delay before it trips and during this period, which may be extremely brief, the current may rise to the maximum the system can sustain. If this fault current exceeds the interrupt capacity of the fuse or breaker it may weld itself in the closed position or otherwise not function correctly." -http://www.pkys.com/circuit_protection.htm

    Its counter intuitive, but the last thing you want is a fuse that does the exact opposite to what its supposed to do. And the wrong device will do exactly that. Large LV DC battery banks are kind of unique in their ability to produce large short circuit currents. Your typical AGM cell has a internal resistance of 1.5 milli ohm, and capable of some serious amps.

    Now the AIC of a typical ANL is 6000A, which is actually much better than i thought, compared to automotive and other garden variety fuses which are significantly less, typically less then 1000A. However a panel mount Carling breaker is 10000A, and the larger 125-250A Carlings are 20000A. These numbers do vary a bit depending on who you ask. BTW a class T is also rated at 20000A.

    Given that the price difference isnt all that much if any, and that you gain a switch, and never being without a fuse, to most of the RE industry, breakers are a a good choice.

    Note: for DC applications you must use a properly rated DC breaker. AC breakers perform poorly with direct current. DC sustain plasma arcs that can easily span the distance across a fuse or breaker that does not have arc supression technology. In practical terms for breakers that limits you to the devices marketed by Outback and Midnite. For fuses, T class / HRC.

    Note2: all fuses and breakers (excpet those that are ignition rated) should be located at least 500mm from a battery. When they blow/trip the resulting arc may start a fire if the battery is venting hydrogen at the time.

    Note3: take care to distingish between ANN and ANL. ANN has a lower 2500A AIC. There is a pretty good summary of fuse AICs here: http://assets.bluesea.com/files/resources/reference/Quick_Guide_to_Blue_Sea_Systems_Fuses_and_Fuse_Holders.pdf and for breakers here http://www.carlingtech.com/sites/default/files/documents/Renewable-Energy-Brochure-09-11.pdf. Note that many of those fuses cant be used on 48V systems, as they have a 32V limit.

    Note4: in general terms its easier to construct a high AIC fuse than it is a high AIC breaker. Fuses will usually trip faster as well. But either way high AIC = high cost.

    Note5: Theres an interesting article on the subject in this old home power mag: 'Overcurrent Protection for Battery-Powered Systems', Christopher Freitas , 1992 http://ketabkhanemelli.com/Scientific/Magazines/Environment/Home.Power.Magazine.Environment/1992.Full/Home.Power.Magazine.Issue.027.1992.02.03.pdf

    My point really is that those using fuses for cost reduction might inadvertently end up with a low AIC product that fails to operate. This is particurly so with system voltages above 12V. 150V DC, Carling and CBi breakers are however an easy and cost effective way to meet AIC requirements.
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
    http://zoneblue.org/cms/page.php?view=off-grid-solar


  • DenyseDenyse Registered Users Posts: 8
    Re: New to solar, need fusing information

    Thank you. I'll check out the links and get informed.
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