As far as wire size Id consult with the manufacturer for their recommendations lest you risk voiding an warranty. That means you have 14.8 amps output to the 12 volt battery which means only 12 volts x 14.8 amps = 177 watts out of 400 watt input. August 3 in Technical Tips and Tricks. Grape Solar GS-400-KIT 400-Watt Off-Grid Solar Panel Kit. Im considering two 400 watt panels (41vmpp per panel with mc4) in parallel for a 12 volt system on a van. If you already have the panels, then be sure you test them for shading before making decisions about parallel or series. You may want to skip forward to about the 2:30 minuet time to see the last panel go up. You can buy it on amazon or a local place which sells welding cable. As far as multiple panel connections are concerned, in series voltage is additive meaning there's less current down to the solar charge controller, however, in series if one panel is shaded that reduces the net energy harvest. It is possible to find the amperage from kilowatts if you know the voltage of the circuit using Watt’s law. Trying to bend #8 or larger stranded wire you buy at a hardware store around tight corners is a real pain. A fairly safe value for most people for amount of Sun is 4.5 hours noon equivalent sun per day. 400 watts / 12.6 volts ( Battery ) = 31.74 amps coming out of the charge controller . HOWEVER that being said let me run a couple calculations FOR EXAMPLES ONLY AND NOT recommendations. New to the site. For the wire size, use a wire size calculator like this one:  http://nooutage.com/vdrop.htm. I am running 120 volts on series panels on my coach, and 240 volts on my series/parallel panels on the house. Nominal Operating Cell Temperature Conditions (NOCT), https://www.solarchoice.net.au/blog/partial-shading-is-bad-for-solar-panels-power-systems/#:~:text=In conventional solar panel strings,as the shadow sits. The solar panel voltage as measured by the controller is 35.4V. --  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. Depending on the intensity and the hours of direct sunlight received through the day, the panel generates between 20- and 30-amp hours (Ah) throughout the day. Great information.   Pasted as rich text. From the roof to the mppt is going to be 8 gauge. 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. Are You Planning a Home Improvement Project? If we assume 6 usable hours of sunlight per day, that's 32.58 amp-hours per day, which is pretty close to our ballpark figure of 30 amp-hours per day. 2) Ive observed situations where MC4 connectors on open rooftops (it can get hot up there in bright sunlight) have failed, but perhaps that was due to excess current ??? Display as a link instead, × ... Then, divide the battery capacity which is 50 AH by the Ampere per hour rating of the solar panel which is 1.25 amps which will be the Charging Time. Two runs of 10 gauge wire, lot easier to run than 6 or 4 gauge I would need if I was running in parallel. Ideal for. Because 1 kilowatt is equal to 1,000 watts, it is possible to use the formulas above to also convert kW to amps, but watts need to be converted to kW first. WindyNation 200 Watt (2pcs 100 Watt) Solar Panel Kit with 1500W VertaMax Power Inverter for RV, Boat, Off-Grid 12 Volt Battery Systems. Watts ( 508 watts for the pair ) amps, remember the equation amps x volts = 300.. 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