Off Grid Solar System Design: 4 Easy Steps + Diagram (load analysis)

In this video, I'm going to show you how to design an off-grid solar system step by step, including how to calculate your energy needs, select the right components, and understand the wiring diagram. This guide is perfect for anyone looking to design and size their own off-grid solar system for a remote cabin or similar application.

First, we will calculate your daily energy needs by determining the watt-hours for each appliance you plan to use. For example, let's say you want to run certain appliances; we find out the power of each device, multiply by the time the device is on, and add these figures together to get the total daily energy consumption. For this system, we have a total daily consumption of 720Wh.

Next, we need to calculate the size of the battery. If we use lithium batteries, we can use 100% of their capacity, whereas lead-acid batteries only allow 50%. Lithium batteries have an efficiency of 95%, while lead-acid batteries have an efficiency of 80%. We also need to account for the inverter's efficiency, which is about 90%. Additionally, we need to ensure three days of autonomy to cover periods without sunlight. Using these factors, we calculate the battery capacity needed. For a 12V system with small appliances, we will use a 12V 800W inverter, resulting in a 200Ah battery. I recommend using the Redodo battery because it's construction is well made with quality components. I trust this brand. They have several options like low temperature protection and two BMS options. One 100A BMS and one 200A BMS. You can have an inverter of 1280W or 2560W.

Then, we determine how many solar panels are needed. We start by checking the sun hours for our location; for Houston, Texas, this is 3.5 sun hours in December. To recharge the battery in one day, we divide the battery capacity by the sun hours, giving us 730W of solar power needed. We choose three 250W solar panels to provide a total of 750W.

Selecting the right charge controller is crucial. We divide the total solar panel power by the charging voltage of a 12V battery. For three 250W panels, we need a 52A charge controller, such as a Victron 150V/60A.

The wiring diagram for the system includes wiring the three panels in series, adding a breaker before the charge controller, and connecting the charge controller to the 12V 200Ah battery with an 80A fuse mounted on a Marine-rated battery fuse terminal. The inverter is attached to the same fuse, using 6 gauge welding cable for the connections.

[BlackjackArmyCaptain]

Thank you, thank you.Thank you.Thank you so much for sharing your knowledge my friend

[TimandLiamsEastcoastkoillc]

Great video . I have to say i got your book off of Amazon and when he got here I was very impressed on how thick it was and I'm about two chapters in and it is great reading and I'm starting to learn and understand the solar power system once I'm done reading the book I will comment

[wilfredopicos]

Saludos espero que tu libro este tan Bueno como tus videos porque acabo de comprarlo em Amazon .Grasias

[malachygallagher]

Hi Nick
Hope you get better soon!
Your videos are excellent!
Can you do a video on calculating capacitors for single phase start/run motors!
Keep it going!
Regards mg.

[Bonifacio_]

Well Done Nick. In a situation were VOC of the Panel is not known how should one do the series-parallel calculation? Thanks

[malachygallagher]

Hi Nick
Love your videos!
Can you do one on sizing capacitors for single phase motors start/run!
Thanks m.

[johncanada]

Excellent introduction. Just bought your book from Amazon.

[danielbornhorst]

Is there a way to add a generator to charge the batteries for extended periods with no sun?

[kennethverhoeven]

could you make a risk analisys video where you explain what happens in all the worst case scenarios like a ground fault at the a battery cable or on one of the pv modules or a short circuit or a parallel/series arc etc. and what components can be used to protect people and equipment from shock/breaking when that happens and how to safely diagnose and repair the system if it does happen

[owolabiadeteye]

Excellent lecture, pls in your calculation for battery sizing, while did you divide the 2, 517Wh by 12.8V, whereas you are using system voltage of 12V. I was expecting you to divide by 12V. Thanks for your effort

[JimNobles-gvky]

Great video:)) Can this system handle the added 7 panels if needed( charge controller size, or inverter size)?So that we could estimate this system maxed out:)))

[LloydMComes]

Hi Nick, I have seen your multiple videos but unable to find answer to my problem. I have 100A MPPT controller, 20-585 W solar panels in series, 12v battery of 185Ah. I have a load of 450Wh, means 24x450=10, 800 Wh perday. Min sun hours 5. My problem is that solar panels are not fully charging batteries. At the end of day battery is exhausted by 30%. I want that whole day solar should run the load and charge the battery as well.
Thanks

[donroher]

I need a bit of help and your suggestions are needed. I live on a remote island n the Alaska rain forest. We have lots of cloudy days. I have 4 each, 255 watt panels. They are roughly 32 volts at 8 amps on a good sunny day. However on a cloudy day only about 13 volts at one or two amps. the panels are hooked in parallel. the controller in use is a Epever MPPT 100 V max, input at 40 amps, charging 2 six volt L16S batteries with a capacity of 380 amp hours in series. Now with the shorter days I have to run our generator to power a 20 amp IOTA battery charger to keep the batteries from dropping below 50 %. Would parallel/series panel connection help to get more out of the panels. The batteries in normal use are enough to provide for our daily use.

[arinzeosigwe]

In choosing a circuit breaker does it have to do with the size of your solar system?

[AdA-dy]

Hi. I have a question. I have a 12v system with 2x 100a batteries in parallel, and a 2000watt inverter. The appliance that uses the most power is my 2000 watt cooker. What size cable should I use to connect the batteries in parallel and what size cable to the inverter? Thanks in advance

[rk_bhartiya]

Full appreciation for your great effort, except calculation mistake for battery size, for 3 days autonomy, multiply by 3×24, please confirm.

[robmaultby]

What about 24v or 48volt systems? with a 3000watt invertor powering a standard household fridge/ freezer?

[ЛУПО]

Assembling the 3*250W solar panels in series or parallel. Describe the point of difference and how it affects the system?

[OrsoGrigio]

are you sure to wire the panels in series? Doesn't it add up to the voltage?

[mainecultivation]

Hello I’m looking for a system that can power 2500 watts continuously for 12 hours what do you guys recommend??