I’m going to talk about how to truly properly size your solar system how much power batteries can really store and the way of solar system really works because it’s pretty amazing how many people that have solar systems don’t truly understand how much power they have and it’s important to know because if you end up with a situation where your modules break your solar panels aren’t functioning.
For a period of time or you have a series of cloudy days it’s good to understand exactly how many kilowatt hours you can actually pull out your battery safely so how many days and how you can ration your power and also that really helps you sighs your system properly without with what appliances you’re using so I’m.
Going to start by explaining how the batteries are set up that first one to say the caps are off the batteries right now because I’m equalizing explain that in another tutorial but hydrogen gas is escaping right now and you don’t want these caps on while that’s happening so right here I have eight Deka LT16 batteries now these are 350 amp hours batteries.
I’m going to explain as part of what i can explain today what that means but before I do that these are set up in two strings parallel together so we have four batteries a group of four batteries that are in series which means that they’re wired from the positive to the negative positive to the negative positive to the negative and then positive to the positive and negative to the negative.
Over to the next string when you wire for batteries in series every time you do that the amperage stays the same but the volts double so each of these batteries is 6 volts so when I put 4 in series i end up with essentially one bigger 24 volt battery the amps are still the same though so what i have here are two 24 volt batteries and then they’re parallel together negative 2 negative and positive to positive and when you parallel.
Two batteries together you double the amprage so i have sized my battery system to make this 24 volts with double the amperage of a single battery so each of these batteries is 350 amp hours ok so first i want to clarify that when your solar panels on the roof the electricity that they generate you’re not using that electricity directly.
You’re never using that electricity directly any time you pull power from solar system you’re always pulling from the batteries the solar panels send electricity to the charge controller and the charge controller reads what the voltage of the battery system is and maybe even a couple other metrics and it determines how it should charge these batteries so if you’re using power during the day the pleading power from these batteries when.
The sun’s out that electricity from the panels is actually directed into the batteries to charge them but it’s not actually but the the power that you’re using your pulling power from the batteries and the solar modules through the charge controller are charging the batteries back up that’s the best way to look at this so that being said you only have as much power to use as what’s stored in the batteries.
What can I power with a 100W solar panel
Hi this is amy at the alte store. we sell a lot of solar panels for diy offgrid solar projects. Generally when we design a solar system, we start with your loads, what you are trying to power, and from there you figure out what size solar panel you need. Weve got lots of tutorials walking you through the calculations . But now we are going to look at it the other way around, what can you power with a 100W solar panel? A solar panel is rated by the amount of power it creates at.
Standard test conditions, or stc. these conditions include the intensity of the sun, 1000 watt per square meter, the angle of the light hitting the panel directly, the temperature, 25 or 77, and other criteria. So as they say, actual mileage may vary, based on all of these factors in the real world. So we generally reduce the calculations based on the difference between the lab setting and your actual installation. When a 12V solar panel is rated at 100W, that is an instantaneous rating, if all of the test conditions are met, when you measure.
The output, the voltage will be about 18 volts and the current will be 5.55 amps. since watts equals volts times amps, 18 volts x 5.55 amps = 100 watts. Watts is like the speed of a car, miles per hour, how fast is it going at that instant, 50 miles per hour. To figure out how much power is generated over a period of time, you can to multiply the watts times the number of hours it is running. So in one hour, 100W x 1 hour = 100 watt hours. Again, with your car, 50 miles per hour x one hour equals 50 miles. Now that we know the math.
Behind it, we need to figure out how many hours to plug into the equation to determine how much power the solar panel will generate in a day. How many hours of sunlight that is equal to the intensity of standard test conditions, which is basically the sun at noon, will the solar panel be exposed to during the day? The number of hours of sunlight equal to noon is called sun hours. As you well know, even though the sun is up at 8 in the morning, it is not as bright as it is at noon. So you cant just say that.
The sun is shining for 10 hours, so ill multiple 100w x 10 hours. the hour between 8 and 9 in the morning is probably only half as strong as the sun from noon to 1 in the afternoon, so the morning hour would probably only be equal to sun hour. But the days are so much shorter in the winter than the summer, the number of sun hours would be dramatically different throughout the year. Also, the amount of sunlight Id get in Miami Florida would be different than the amount of sun hours Id get in Portland Maine. Ugh, this can.
Get complicated. luckily, some very smart people have taken decades worth of weather data and calculated out the number of sun hours for all over the world, broken out by month, and even the tilt angle that the panels are mounted. So I can look at the charts to see if I have a 100W solar panel, in Portland, Maine, installed at about 45 degrees angle, on annual average, Id get 4.6 sun hours a day. Likewise, if I took that same solar panel in Miami Florida, installed it at a 25 degree tilt, Id have an annual average.
Of 5.2 sun hours. just as a little aside, i want to make sure you see that during the months of June and July, Im going to get more power out of that solar panel in Maine than I will in Florida. With Miami being closer to the equator and Maine being closer to the north pole, the days are longer in the summer in Maine, and so the sun shines on the solar panels longer. Kind of cool, huh? OK, back to the question at hand, what can I power with a 100W solar panel? I need to figure out my worst case scenario, what is the worst.
Performing month that ill be using the panel? since for this example im going to be using it in Maine, during ski season, I need to figure on December. So how can I squeeze out as much power as I possibly can in December? By tilting the solar panel steeper so it points right at the low winter sun. So Im going to mount my 100W solar panel at 60 degrees and figure on 3.2 sun hours. Ill now take 100W x 3.2 sun hours and get 320 watt hours a day in December. Now, as you know, nothing in real life is perfect,.