How Much Solar Power Do I Need? How to Calculate Your Needs

Hey everybody Michael here with you, a justice welcome to today’s. Video, if you’ve got a chance to see last week’s. Video. I talked about the goals of this Solar series as well as some things you need to consider.

If you’re still asking yourself is solar power right for me now, if you’re asking yourself that question be sure to go check out that video first, but for those of you who have made the decision to move forward with Your solar ambitions today, I’m gonna be talking about how to properly size your solar system.

Before I jump into today’s topic, I’m gonna take the time to remind you to hit that red subscribe button below. If you haven’t already, there’s, also a bell icon right next to that that will keep you notified and up-to-date on any future videos that we post in this series.

Ok, now that I got that out of the way let’s get started so how much solar do you need? Well, what I’m about to tell you is the most important thing you need to remember when designing any solar system.

Every component you buy and every decision you make regarding your solar system, revolves around the idea of knowing how much power you need to power. The appliances that you want, for example, the size of your solar array, aka.

The number of solar panels that you need solely depends on how much energy you use on a daily basis. The size of your battery bank depends on how many days you want your energy storage to last you through cloudy days, the charge controller you need.

It needs to properly manage the energy between your solar panels and your battery banks, and the inverter you need depends on what appliances you want to run off your system. Even the sizes of wires and fuses depends on how much energy is going to be flowing through them, so you may be asking yourself: how do i size my system? How do I know how to calculate all this stuff? Well, I’m gonna go ahead and tell you right now.

The first thing you need to do is you need to list out every appliance that you intend to run off your solar system. I know this might sound tedious, but you need to go around to every appliance and find what’s called the power consumption rating label.

This is a label that could either be imprinted on the device or charger itself or it’s. Printed on a label that is stuck to the device or charger what you’re gonna want to be looking for is the output rating for the device.

Now this can either be listed as watts or volts and amps or milliamps. Ultimately, what you’re going to be looking for is the wattage of the device. If it already says it on the label, go ahead and write that number down.

But if you’re left with volts and amps, I’m gonna give you an easy equation to use, so you can convert those into your output wattage. The equation is, Watts, equals volts times amps and if you have milliamps, as your variable, all you’re.

Going to need to do is take that number and divide that by a thousand. So if you have five hundred milliamps divide that by a thousand, that will give you point five amps. If, for some reason, you can’t locate the power consumption rating label, try to find the model number of your device and either Google search it or just find something that’s similar to it online so that you can get an Idea of how much power that will draw once you list out every appliance that you intend to use with your solar power system, along with the corresponding output wattage, what you’re gonna want to do! Is you’re gonna? Ask yourself with each appliance: how long are you gonna use it each day and for this number, you’re, going to use hours as your variable.

So if you & # 39, re gonna use an appliance two hours a day. You’re gonna write down two in that space. If you’re gonna use it and apply in 30 minutes, you’re gonna write down 0.5 hours. If you’re gonna use, an appliance 15 minutes write down 0.

2 five hours. I think you get the point after you’ve written down all of the hours that you intend to use all of your appliances. What you’re gonna want to do is take the output wattage and multiply that by the hours per day that you intend to use each device.

For example, let’s. Take that 85 watt computer charger that we had earlier. We’re gonna take that 85 and multiply it by the four hours we intend to use it and then, since we have two of those chargers, we’re gonna multiply that by two so 85 times 4 times 2 is Going to give you about 680 watt hours per day, you’ll, want to repeat this process for each appliance that you have on your list and at the end of it all each appliance should have a corresponding watt hour figure.

Now, with all of those watt-hour figures, you’re gonna want to add them up and at the end of your list, you should have a figure that is the total number of watt hours that you’re, going to be using On a daily basis, with your solar system, now that you have your total watts per hour that you intend to use on your system, what you’re going to want to do is calculate your solar needs, and to do this, you can go in One of two directions you could either go nerdy like I did and try to find the technical details and energy losses in the system, or you could use this really easy calculator online and for the sake of ease, I’m gonna use the Online calculator, so I’m gonna jump on the computer and show you guys exactly what you need to do.

Ok guys, I’m here online, taking you through a real-time walkthrough of how to properly sized your solar system, and I’m here on the alt East or solar calculator. If you type in solar calculator onto the computer on to Google, you will find a million calculators.

The only reason I’m using this one is because it made the most sense to me, and I hope it will to you as well. If you want to see the link to this solar calculator, I will have it in the video description below.

So if you want to follow along, go ahead and go to the video description and click on that link – and I will take you through it right now, so when it comes to battery bank sizing, this, this website is actually going to calculate the size of your Battery bank, your solar panels and your charge controller, so it’s, going to do three separate things, but we’re, going to first start with a battery bank sizing.

Now, when it comes to the battery bank sizing here in step one, it says you need the total number of watt hours per day. Now when it comes to that we just calculated that number out, and if you recall from our previous spreadsheet, we had 2030 point.

Five: five total watt hours per day that we consume and that’s, going to take us now to step two and it’s, going to ask you how many days you want your solar system to run without Sun. This is basically saying during cloudy days how many days of storage do you want for your battery bank and for our specific needs? We just decided to go ahead and do two days.

This is on the low end because we travel around in an RV and we can kind of compensate for the lack of Sun by moving to different occations. But if you’re in a stationary position with enough money and enough space to store all these batteries, you’re, probably going to want to do more like anywhere from five to seven days of storage.

But basically what I & #! 39 m gonna do is I’m going to type in two, because that’s for our system. It works best for us again. We’re, just showing you what works well for us. So now, on to step three, we’re, going to talk about the lowest amount of temperature that your batteries are exposed to and for us again, since we move around, we don’t, get into freezing temperatures that frequently, but worst-case scenario: 30 degrees is going to be the lowest that our battery bank is going to see and again, if you live in a warmer climate, you’re gonna be warmer.

If you live in a colder climate, go ahead and put 20 degrees. This just gives them a good idea of how the batteries will be able to function in the temperatures that they’re, going to be exposed to now that you got that all entered in it & # 39.

S got the results here and you & # 39. Ve got the total number of watt hours that you need for your battery, but for our specific circumstances, we’re, going to be focusing on this right here. It’s. The number of amp hours that you need for your battery bank, because in the solar battery category they usually categorize everything in amp hours, not in watt hours.

So for us we need 1090 amp hours of battery bank. Just keep in mind. This compensates for a 50 % discharge rates of your batteries, depending on the type of technologies that you use for your batteries.

Most of them can only be discharged about 50 percent before you actually damage the batteries. I will go into a lot more of this in the future, but this calculator already compensates for that 50 percent discharge.

So keep that in mind, if you’re using a newer technology like lithium-ion, where you can get 80 plus percentage of usage out of the battery. Just keep that in mind that the calculations are going to be off.

Also right here, you’ll notice that it’s, 12 24 or 48 volt systems for our system. It’s a small system, so we’re, going to keep it a 12-volt system. If you do have a larger system, you might be 24 or 48 volts.

I will explain more of that in the future. If you are going to be doing that, but for our circumstance, we’re, going to be keeping it at a 12 volt system. Okay, now that we’re done sizing the battery back, we’ve got it here at 1090 amp-hours, we’re gonna go ahead and go on to the solar panels and the charge controller sizing, and for this the First, step takes you into the average sunlight per day that you get in your area, so this is for the United States.

It has a bunch of major cities that you can type in and for us, I’m gonna go ahead and type in our original home state in city, where we started from we launched from Columbia, Missouri – and this is this – gives you about 3.

2 hours of sunlight on average per day now, to give you a generalized idea of different areas of the world and the United States, where you get different amounts of sunlight, you can go ahead and click on this map here and that will take you through.

As you see, the different colors represent different amounts of sunlight per day, so we decided to just enter in an average of about 4 hours per day and the reason we did that did. That is because we were going to be traveling between the Northeast and the southwest of the United States and, as you see in the southwest, it gets anywhere from you know.

Five to six and in the Northeast gets anywhere from maybe one to three. So we just decided to average out it out at about four. So if you need to see the different areas and locations and the averages go ahead and click on that map, but I’m gonna go ahead and navigate back to our solar calculator, and I’m gonna enter in four Hours for our not 34 hours, four hours for our average sunlight per day now in step, two, it’s, going to give you the amount of watts that you need based on your total consumption and that lots of solar panels that you need.

So this is about six hundred and sixty watts of solar panels that you need, and then the last thing you need to know last couple things you really need to know is how many watts per panel are you gonna have for us? We decided to go with a hundred and fifty watt panel, but again there are a bunch of different options, as you can see here.

So if we chose 150 watt panels, we would need five panels. That would give us about 750 watts of energy. Now that’s, 750 watts of energy is obviously more than 660 that we currently need, but what it’s going to do.

Is it’s, going to always overcompensate for the of watts that you need? So if you had maybe let’s, say hundred watt panels, you would only need seven panels for 700 watts, because that puts you the closest number, that’s above 660.

So, but for our situation again, we chose 150 watt panels and it’ll, give us five panels that will produce 750 watts of power. The last thing you’re going to need to know is the solar charge controller sizing? Basically, our solar charge controller needs to be capable of handling about 63 amps of current going between the solar panels and the batteries.

So now that you have a good idea of what your system will require, I encourage you to go out and do some more research on what’s out there, but it may seem overwhelming because there’s, tons of options and combinations Of components that you can put together to create your system, but I want to reassure you that I will be covering all of this material.

The major components as well as what we incorporated into our system in future videos also now would probably be a good time to go back and look at those limitations that I talked about in the previous video, specifically the space limitation, the budget limitation and the place That you live geographically limitation and if, for some reason that those limitations are conflicting with your needs, it’s not over.

You can do something about it. If you need to go back to your appliance list, look at the appliances that you can do without and then cross them off. Recalculate your needs wash rinse and repeat: okay, guys, I’m jumping back here on the solar calculator and, as you saw, Jenny went ahead and sacrificed one for the team.

We decided to go ahead and take the hair dryer off the appliances that we were going to use with our solar system. There’s, a lot of factors that go into that, but basically I had to do with budget and spatial limitations at the time of us calculating our solar needs.

It also has to do with the amount, the size of the inverter that we need to power that appliance, so all of that taken into account. Basically, what I’m going to do is I’m, going to go ahead and enter in our new watt hours per day after the hair.

Dryers were moved from that list, and that leaves us with about fifteen hundred and sixty two don’t forget to press ENTER. If you go ahead and recalculate this as you & # 39, ll, see nothing changes in step two or three, but you’ll notice that the results are much different.

Instead of about 1000 and 960 amp hours of battery, we only need 839 amp hours and then, when it comes to the solar panels and the charge controller, again, nothing changes with the average sunlight per day.

But you do notice that, instead of needing 660 watts of panels, you only need 507 watts, so that reduces the number of panels that we need from five 150 watt panels down to just four and that’s exactly what we have in our system.

Also, the last thing you’ll notice. Is the solar charge controller instead of needing to compensate for about 63 amps of current? It only needs to compensate for about 50 amps of current. Just from removing that hairdryer, you may need to make some sacrifices on your end, but if you really want solar power to work for you and your specific needs, that may be the only option that you have: okay, guys that’s gonna.

Do it for me, I hope you enjoyed this video on how to properly size your solar system, if you did make sure to hit that like button down below also, let us know what you think in the comment section below and you guys know the drill.