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200W solar panels are fast becoming the standard power range for RVs and portable solar users. It’s obviously got more power than the 100W panel but doesn’t require as much space as a 400W panel or array. Like all solar panels, power is measured in watts. But what if you want to convert it to amps? How would you know how many amps is in a 200W solar panel?
There is 11.1 amps in a 200W solar panel. The calculation formula is watts / volts = amps. In this example it is an 18 volt, 200W solar power system, so 200 / 18 = 11.1. This is the basic process but you have to consider other factors if you require more precise numbers or calculate other voltage systems.
How to Convert Solar Panel Watts into Amps
The example above shows you must know the system’s voltage to find the amps. If it’s 18V you divide the wattage by 18. If it’s 24, 36, 48 etc., replace 18 with that figure. If our 200W solar system uses 36V, the amps would be 5.5 instead of 11.1.
A 200 watt 12V solar panel delivers up to 18 volts when it charges, so it produces 11.1 amps. To reach 18 volts you need a high quality solar panel like the Newpowa 12V monocrystalline Solar System which is designed for RVs, homes and off grid locations.
If you know the amps and volts and want to find the watts, it’s amps x volts = watts. With these conversion formulas you’ll have no trouble figuring your solar panel’s wattage or amperage. But why is the result similar in all 200W solar panels regardless of brand? The answer has to do with how solar panels produce current.
Amps and Volts Explained
Solar panel sizes differ, but each panel segment usually generates 0.5 volts. It is the size of each one that determines how much amps the panel will generate. For 18 load volts that’s 36 segments. This specification is ideal for 12V batteries including our favorite the Mighty Max ML-100 because it needs a voltage system greater than 12V. This applies to all batteries: the voltage panel must always be greater than the voltage of the battery you are charging.
You can also see why we used 18 volts in our example instead of 12 volts, which many consider as the “standard”. As explained above, your voltage panel has to be higher than the battery voltage. If you tried 12 load volts on a 12V battery, it won’t work. You need at least 18V to produce a charge.
Solar panels often have 36 segments for 18V load. In other systems you may see 36 load volts and 72 panels. For more power you can configure two or three of them in a parallel or series to produce more amps. if you wired three then you’ve got 108V load. With this setup it’s easy to charge 36V and higher batteries above 50 volts.
Load Volt vs. Open Circuit Voltage. We want to make clear we are referring to load voltage and not open circuit voltage. These are not the same as open circuit voltage is higher. If your load volt is 18V then the open circuit voltage will be around 21V. We put more emphasis on load voltage because voltage always goes down when there’s a load. it’s the voltage and the amps that generate the wattage for your system.
Why is My Solar Panel Not Showing Amps?
If you place a 200W solar panel (or any panel size) under sunlight, you won’t see any amps on the display readout. You see the open circuit voltage but no amps. Even if you turn the panel from the sun there’s still no amps. Don’t worry there’s nothing wrong with your system.
Now hook the panel to a load. You’ll see the voltage drop and amps appear. For best results you should get a charge controller (preferably MPPT). It will lower the voltage to the optimum level as the battery starts to charge.
Can a 200W Solar Panel Charge a 100ah (amp hour) Battery?
Yes, a 200W solar panel can charge a 100ah battery in about 5 hours. But you should know some facts and figures behind so you’ll understand why on certain occasions, the charge takes longer.
In this example we’re using the typical 12 volt,100ah deep cycle battery, 12 volts x 100ah = 1200 wh (watt hours). Proper use means recharging at 50%, so you just need 600 watts to fully charge the battery.
A 200W solar panel can’t produce 200 watts an hour even under perfect condition. Some power will be inevitably lost. But even under less than ideal circumstances it should be enough. If the panel produces 120 watts an hour (just above 50% of its possible output), the battery gets charged in 5 hours.
Under sunny weather it will take less time, maybe 4 hours or so. It’s another matter if it’s overcast. In that case expect charge time to take longer, maybe double. We’re also assuming best battery practices and maintenance, i.e. you’re recharging at 50%. Expect charge time to take 12 hours or more if the battery is completely depleted.
The 5 hour charge time also assumes there is at least 5 hours of sunlight. More sun plus proper solar panel positioning and you’ll see a faster charge. This rule is applicable to all batteries and solar panels. You should also have a charge controller installed to ensure the process runs smoothly.
Can a 200W Solar Panel Charge a 200ah (amp hour) Battery?
But suppose we double the battery capacity to 200ah. can your solar panel still deliver? The answer is yes, but again the charge time will depend on the factors mentioned above. Namely, sunlight availability and battery level depletion.
On a good day a 200W solar panel produces around 15 amp hours. So you just multiply that by the depth discharge for the battery.
If you start with a 35% depth discharge, you need 67 amp hours to top the battery (from 200 to 133 is 35%). A solar panel that generates 15 amp/hours needs 4 and half hours to fully charge it under full sunshine.
If the depth discharge is at 50% (100 amps down from 200), it will take the panel 7 hours to top it off. Under less than ideal conditions be prepared to wait longer.
But what if you need all 200 amp hours from the battery? Can’t you just drain it to 0% and charge it? We don’t advise that because it will take days to top a 100% depleted battery. A better choice is to buy a 400ah or 600ah battery. Pair this with a 300W solar panel and you’re set.
With a 300W solar panel you can use 200ah and it will take about 10 hours to fully recharge. If you can get two 200W panels, that’s even better and will take less time. But before you buy, determine how much solar power you actually need so you don’t end up spending too much on power you will not use. If you’re just charging phones, a portable solar charger will do.
Figuring out all the volts, amps and watts might seem confusing at first. But it’s necessary and as we’ve shown, really quite simple. Once you have the formula, you can use it to calculate the power of your solar panel easily. This is what allows you to make the most out of your system.