diy solar

diy solar

I need help. Tiny Off grid DIY LiFePO4 system.

tekids

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Oct 31, 2020
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Hello. I'm new to solar and I'm trying to make a simple and cheap system just to power the following:

4 mobile devices
1 laptop
1 fan
4 lights

I decided that the following system will be able to satisfy these needs (please correct me if I'm wrong)

1 12V 100W Solar Panel
12v 100Ah LiFePO4 Battery (I will be making this with prismatic 3.2V 100Ah batteries in series and a 100A BMS)
20amp mppt controller
750W psw inverter
Fusebox


I'm inspired by the basic 12V BMS Protected LiFePO4 System here on the website but when I check the other systems (like the diy solar generator), a battery protect, circuit breakers, etc. were being added and it's confusing me on what I really need to properly take care of the system.

Did I size everything correctly? To maximize the system, do I need to increase or decrease anything? How do I connect the BMS to the fusebox because the wire gauge is different? The fusebox I find online only has one main port and not the ones in the video. I'm also concerned about the temperature because I live in a tropical climate. If I wanna add another solar panel then do I do it in parallel or series?

I apologize in advance for my lack of knowledge. Thank you so much for taking the time to read this.
 
Well... you list the devices you wish to power, but not the watts they draw.
“Lights” could mean very different things...
same with fan, and mobile devices...

to know if you have sized things correctly, we need to know the wattage consumption for the loads...
A 4W LED, will pull far less than a 20W fluorescent, or a 250W flood light.
Same goes for portable... etc.
To know what loads total, having a Wh meter ant actually testing the load is important.
 
The power audit process will help you understand your needs much better.

You need to work out how many watts each item will use on average each day

This will help you size your battery and inverter properly

From this info you will also be able to size your solar panels so they can replace the power used easily

Where about are you in the world?
 
Welcome to the Forums!

Hello. I'm new to solar and I'm trying to make a simple and cheap system just to power the following:
So, you'll first want to do an energy audit as suggested above, see my signature below for a link to get you started on that.

I decided that the following system will be able to satisfy these needs (please correct me if I'm wrong)...Did I size everything correctly?
We can't know/help without the energy audit.

I'm inspired by the basic 12V BMS Protected LiFePO4 System here on the website but when I check the other systems (like the diy solar generator), a battery protect, circuit breakers, etc. were being added and it's confusing me on what I really need to properly take care of the system.
Batteries make solar expensive currently. If you live somewhere with net-metering, you'll get more bang for your $ by skipping over the batteries for a few years.

If I wanna add another solar panel then do I do it in parallel or series?
This might help: What does it mean to have solar panels in parallel and series?
You might also check out some of the other entries in the FAQ section.

WHY [why why why]? ... And what the hell is it with people wanting to use pissy little 100W Panels all the time??
Somebody woke up on the wrong side of the solar panel, stubbed their tow, spilt their coffee on the missus's new blouse, and got judgmental! ? I also agree about how much more they'd learn with a larger scale and they'd be better served saving until they get a system they have a hope of growing rather than having to throw out in a year because the components won't scale economically.

Small panels are used for small places (e.g., RV roof geometries), were you need something easily portable, old geezers like me that can't lift a big panel onto the roof, or the worst possible reason.... they're all shiny and cute looking at the big box store and the marketing is geared toward the impulse buy rather than something meaningful.
 
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WHY?

Why do you want to make a system to power these low draw devices?
The cost to do this is going to be magnitudes more than the cost of the power you could save. You obviously have power or you'd be wanting to power a lot more things.

And what the hell is it with people wanting to use pissy little 100W Panels all the time??
If this is just to much around and play Tiddly winks, Fair enough. In that case you'll learn a lot more by doing so add a Multi-meter to the list , spend you money, set it up and run with it and see what happens. You WILL learn a lot and can see how solar actually works. You really need to be doing more homework before asking these questions but putting it into practice will teach you more than any questions or amount there of you could ask.

I would suggest upping the game a bit and get something that uses real power and put in some real panels and generation capacity.
When you start putting in real loads, you'll see how the game changes. Try powering a Fridge and your Kettle. Those real and Ongoing practical loads will give you a far better idea of what solar really takes.
I have a condo with an HOA, and getting decent solar would be challenging.
My homestead in Belmont has a ton of solar, but it’s hard in the condo. I have a 300WATT array on my suburban, and a 375W panel leaning against the patio wall... fine for powering solar generators, and charging laptops and such...
keeps my projects off the grid.

I’m not sure why you wanna be on this forum if helping new people learn is so irritating to you.

This site is here for members to learn, and for the more experienced With free time to assist.

I think Will said it best, sometimes it’s best to just hit like, and move on. Commenting isn’t needed sometimes.
 
Well the OP isn’t going to learn anything here, he’ll have run for the hills

Note - this post is in beginners corner, a place designated for beginners to ask newbie questions

Come on guys, play nicely with the newbies
 
Maybe the OP simply wants a small backup for essentials with a potential power failure. That's what I have although it is 400w of panels and 220AH of storage, two packs, one is also used with my kayak.
 
100ah lifepo4 equates to about 80ah of usable capacity or about 1000watt hrs.

You want a solar array that your replenish the usable capacity of your battery in 4hrs of sunlight (4-5hrs is a good rule of thumb).

A 20amp mppt controller will allow you to use 250-260w of solar. Solar panels are cheap, I would get the biggest you can fit and at the highest open circuit voltage your controller is rated for.
 
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