A 500 amp battery disconnect doesn't have near the resistance as a 50 amp fuse or CB. HOWEVER AGAIN even bigger wire (say 2 or 4 Gauge) = less voltage drop and I have seen 4 Gauge (even if overkill based on current) used under similar conditions PROVIDED all the connections are suitable for that size wire ???? Parts List: 2 – Renogy 100 Watts 12 Volts Monocrystalline Solar Panel Plus, check out the formula for the conversion with example calculations. Cause that's what I have, and according to my Charge Controller it's only putting out 5 amps on sunny days, I thought I would be getting more amps like 25-30 amps. All home systems run in series or series/parallel at high voltage because it is just not practical to run high amperage cables. I plan on using mc4 combine connectors with 20amp fuses to combine the 2 panels on the roof. The same goes for the 2 to 4 feet of the heavier cable (#2 to 4/0) to go from the controller to the batteries or battery to inverter. It is a minor cost to go from 3% loss to 1% loss. That panel is rated at 100 watts at peak efficiency – meaning on a 78 degree cloudless day at solar noon on the equator during the equinox. It is my understanding that cutting off the MC4 connector will void the solar panel warranty. Here is what conditions the spec sheet states is Nominal, as versus "Standard Test Conditions" which would only happen in a lab environment. This means, that at 400 watts and 12.6v we can expect up to 31.74 amps coming out of the solar controller. ALL SUBJECT TO any max input voltage range of your charge controller, although many MPPT have a wide input voltage range maybe even as high as 100 volts or more. The solar panel voltage as measured by the controller is 35.4V. Using this, we learn that this panel will produce 25 amps. Hello. Check Wire, Lug, and Fuse List at Bottom of List You are planning on putting the solar panels on a van. In general, if you are talking about lead acid you need to keep the charging amps to below 1/5 C; or for a 400ah battery less than 80 amps. I don't have any MC4 specs or data sheets handy to see what size wire they can accept. https://www.solarchoice.net.au/blog/partial-shading-is-bad-for-solar-panels-power-systems/#:~:text=In conventional solar panel strings,as the shadow sitsI. current = 10A. I … Ideal for. Use our kW to amps calculator to solve for kilowatts. Help mount solar panels to the roof; Qty: 1 – MC4 Connectors. Everything thing is 12volt in the van also. Started September 29, By --  For the wire run to your controller: Measure the distance from the combiner box to the controller, then in the voltage drop calculator use the max amperage & voltage output of both panels, and buy the wire size that gives you less than 1% loss. A 300 watt solar panel on a 12 volt system should have how many amps in it? Solar Charging System: Qty: 1 – 300 Watt Solar Panel – 2 Pack. Everything thing is 12volt in the van also. I'm considering two 400 watt panels (41vmpp per panel with mc4) in parallel for a 12 volt system on a van. By   Pasted as rich text. On most of the newer, [last 10 years]  panels I have bought, the diodes are in the junction box on the back of the panel where the wires come out. If you have a 75-watt panel and 5 hours of sun per day, you would produce 375 watts per day per panel. Also, can mc4 connectors be attached to 2 and 4 gauge? They simply use the array current. At a full charge, a 100 watt light bulb ( incandescent) lasts less than 2 hours before the inverter shuts down. I have heard about panels with diodes, but have not seen diodes mentioned in the panels specs I have looked at in the past. You can buy it on amazon or a local place which sells welding cable. × And new to solar. $40 for 50 ft of 10 gauge,  $100+ for 50 feet of 4 or 6 gauge. This state-of-the-art 400 watt solar panel with Pure Black™ technology optimizes power, performance and aesthetics. I plan on using mc4 combine connectors with 20amp fuses to combine the 2 panels on the roof. New to the site. I would greatly appreciate your knowledge and experience. I am concerned about sun blocking/ shade over panels. The controller shows that it is putting out: 520 watts. There are two types of mc-4 connectors. As far as wire size Id consult with the manufacturer for their recommendations lest you risk voiding an warranty. Fusing from panel to controller is not needed, and causes an extra voltage drop. By Jason, thanks for the update, here's my response: 1) 8 Gauge copper is rated FOR AT LEAST 40 Amps, subject to if jacketed or in conduit or single conductors in open air which makes it even greater, so the possible 15 to 30 amps of current I used above should make it adequate being 15 ft shouldn't cause any excess line voltage drop. 99. Therefore, if the solar array can produce 40 amps of current and the charge controller you’re using is only rated to 30 amps, then the controller could be damaged. 1) If your two panels were producing full 800 watts (Yeah right lol) at lets use ONLY FOR AN EXAMPLE  24 Volts (even though it should be higher) 800/24         =   33 Amps, 2) If your two panels were producing 800 watts at 41 volts, 800/41 =   19.5 Amps, 3) Next there will be a line voltage drop from the panels to your solar charge controller which depends on 1) Current 2) Wire size and 3 ) Distance and if its excessive you would increase the wire size, Okay, that all being said and NOT knowing your actual current (depends on sun and panels etc) and NOT knowing the wire length but ONLY what my training and experience has taught me,  if I were doing it and had NO OTHER instructions to follow, I might use a very MINIMUM of say 8 Gauge (subject to length and larger if necessary to reduce line voltage drop) fine stranded copper conductors, Marine grade moisture and UV rated insulation. 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