diy solar

diy solar

Please advise

Kos

Kos

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Joined
Jan 7, 2021
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21
Hello.
Forgive me I'm a beginner. Had to start from somewhere, so
I just bought 4PCS LiitoKala 3.2V 280Ah lifepo4 battery DIY 12V 280AH rechargeable battery pack and 3x280w solar panels.
Can you please advise what gadgets will be needed in between these batteries and the solar panels for a smooth operation of my DIY system?
 
What is the Voc of your solar panels?
Do you have a solar charge controller budget or idea what quality/reliability range?
 
Thank you for your reply.
Forgive me Voc?
Yes budget ok. Whatever is best and needed I'm in
 
Called the warehouse and said probably around 40Voc but I will have confirmation of this number later on today.
Thanks again for the reply
Will be back later on
 
Kos said:
Called the warehouse and said probably around 40Voc but I will have confirmation of this number later on today.
Thanks again for the reply
Will be back later on
Click to expand...
Look at the back of your solar panel. Should be a sticker there with several stats. If you can post a pic of that, it would make your life and the lives of people helping you easier.
 
Sorry brother i didn't collect the panels yet. Waiting for the back up from the warehouse. Told me in the evening Athens gr. time.
Thanks for your patience and will to help me. I will post the info as soon as I get it.
Thanks again
 
Hello
Seems like i got no feedback from the warehouse. Probably i will cancel my order with them.
Let's assume i will cancel. Can you please include in your suggestions on which gadgets are needed, the kinds of panels aswell?
Thanks again for your patience and your will to help
 
There are some blueprints for different sized systems on the sister site:
www.mobile-solarpower.com

Mobile Solar Power: Made Easy! DIY Off-grid Solar Power!

Building a vehicle mounted solar power system? Let me help.
www.mobile-solarpower.com

If you find something that looks similar to what you are trying to do, it should have a good list of parts.
If you have to charge one of these blueprints to better suit what YOU want to do, we can likely suggest
how to accomplish this.

You should perform an energy audit to get an idea how much power your system needs to product for your goals.
This will help you size the system to meet those needs. It saves a LOT of money in the long run.

The size of your array will need to harvest more energy than your daily use. Your batteries will need to store the energy for use outside of solar harvesting times. The last big piece is the solar charge controller that works with the panels you've selected and battery bank. The blueprints will detail all the connecting pieces.
 
Thanks for your reply.
As i mention earlier I bought 4PCS LiitoKala 3.2V 280Ah lifepo4 battery DIY 12V 280AH rechargeable battery pack.
Thinking of buying a dali 250A bms and a 4000w inverter.
About the panels from what I read 800w in total will it be able to go with this batteries?
 
Kos said:
About the panels from what I read 800w in total will it be able to go with this batteries?
Click to expand...
800w / 12.8v = 62.5a

Yes, that is a good size.

You should be very mindful of the Voc of the panels you purchase. That will dictate which SCCs will work well with it.

A top rated SCC such as the Victron 150/60 will provide 60a of charge current. The trick for matching panels is to have the array voltage around 130-140Voc.

For example 3x 300w panels with a Voc of 40 each, in series would produce and array Voc of 3x 40 = 120. This is a good fit.
Perhaps up to 45Voc good for Athens because it does not get freezing temps often.

Whereas 48Voc would be a bad fit as you could only get 2 in series to safely stay below 150Voc.

Voc is rated for 25deg C. As temps drop, voltage increases by about .4% per degree.

Exceeding input voltage on SCCs is usually very bad.

So if you find panels, check in if you want someone to evaluate if they can be setup to work for you. Before buying (this mistake has hurt a few people lately and its an expensive mistake).
 
Here is a new thread that might interest you.
It involves determining power needs and sizing an inverter and BMS(s).

diysolarforum.com

8p4s battery bank?

Hi, I intend to purchase 32 fortune 100ah batteries. I want to stay with 12v I want to use a 8p4s configuration for 800ah GIANDEL 4000W Heavy Duty Pure Sine Wave Power Inverter DC12V to AC120V It has been suggested by seller of batteries to use 4p4s X 2 with two 200a BMS to an appropriate amp...
diysolarforum.com diysolarforum.com
 
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Hello
I just want to power only basic stuff of the house lights, modems, fridge and washing machine average use. For now at least since I'm learning everything from the internet..?
 
You REALLY should do an energy audit. This is a necessary first step, and if you are interested in learning, this will teach you the most important things.

Really.

There is an energy audit link in my signature.

The tricky bit of what you are powering will be the washing machine. The motor in it will require a pure sine was inverter. And, the surge amps can be 5-10x more than running current.

Everything else will be how many watts they use and how long they run each day (in watt hours).

Its hard to go wrong from there.
 
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Thanks again for your reply
I know about the washing machine possible issue so a fast wash up to 40c for 30min during sunlight I think it can do the job. But not sure. Looking for the link you mentioned above the energy audit link but I can't find it
 
Thanks
Just managed to see it.
By the way finally i got the specs for the panels. Let me know what you think.
 

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Kos said:
By the way finally i got the specs for the panels.
Click to expand...
Great. 39Vc is the critical number when selecting a SCC.
3 of these in series is 117v and would be a nice fit for a lot of inverters that take 145-150 max input voltage.

The question is how many watt hours per day your array has to replace and this is the number you get from your energy audit (it all comes down to covering this number!).

And you can determine your expected charging hours here:
How many "solar hours" of sun do I get per day throughout the entire day at a city near me?

Take your expected daily use in watt hours (different for summer and winter?) and divide by the number of "solar hours" (try for summer and winter) to get the size of your array operating at 100% efficiency. You should add 25-50% of the calculated array size for your daily use.

If you want to plan for rainy days, you'll need more batteries to cover that and more solar to recharge more than a single day of use back into the batteries.

Make sense? If you share the numbers you come up with we can do a sanity check.
 
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