diy solar

diy solar

Need Help building a system I will expand later- several questions

Mountianview

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Jul 28, 2020
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I need to build out a functional battery/ inverter system that I would like to expand and refine later. I have about a $1200 budget to work with but I can stretch that to a higher number if it were critical. The vehicle? A step van. In some ways its pretty much ideal for a solar system even though that's not what I need to start with. There are some reasons that wouldn't seem obvious without explanation, so let me cover that. I need to do all this in short order, I have several demands on my time, and when I add solar panels I want to have a roof rack and do a professional quality job. Also, I have some concerns about stealth. For these reasons and more I've decided that I'll be better off sticking with an alternator charged system. I know just like any system there are limitations to these designs and I'm hoping to live within those limitations until I can add solar. I had the thought that I could have a generator in storage and run it for an hour or so to charge my system if the alternator didn't keep up.

What I've got in my head so far:

Batteries:
4 Fortune 100Ah Lithium Battery LiFePO4
https://www.electriccarpartscompany.com/Fortune-100Ah-Aluminum-Encased-Battery

Inverter:
Giandel Pure Sine Wave Power Inverter 3000Watt
https://www.amazon.com/Inverter-3000Watt-120Volt-Display-GIANDEL/dp/B07NZN4K48/ref=sr_1_13?dchild=1&keywords=3000+inverter&qid=1595951547&sr=8-13


Renogy 40A 40A DC to DC Battery Charger- this is one of the recommendations Will has for this type of charging, yes?
https://www.amazon.com/dp/B07Q4SVX3M/?coliid=IWGAN0W61VXNM&colid=3NF7HCA9Y4SLM&psc=1&ref_=lv_ov_lig_dp_it


While I have a background working with electricity, I have no experience with solar other than casually watching youtube videos, so I'm here asking for help with this project. I know I've left things out- (BMS, battery heat pad, and???)

I picked the batteries based on price and Will's recommendation, the same goes for the Inverter and DC to DC charger. The inverter size was based on the heaviest load I anticipate and the manufacturer's recommendation.

Questions:

On batteries- I thought I would start out with a twelve volt system, but when I add Solar I might transition to 24v. Additionally I might add additional battery capacity, but I vaguely remember that adding batteries later is not recommended. Do I have this right? If so I guess I need to either use the minimum battery capacity to replace later, or alternately max out on batteries now, correct?

DC to DC charger: how do you correctly size these things? All I can tell you right now is that I believe that alternator is a 105 Amp alternator as that appears to be stock for this truck.

Are there any key components I'm leaving out? Is this a big hot mess only suitable for abandonment? Any other advice?

About the only other thing I can add is that when I do add Solar it will be in the 300-800 watt range.

Thanks for all your advice!
 
Not sure what your loads are, but I don't think you will be able to supply the full 3000W from 4 of those cells. They are rated for 2C continuous. You may want to consider 8 cells. You can run them in 2P4S for 12V and that will give you the flexibility to change to 8S if you need 24V down the road.
 
On batteries- I thought I would start out with a twelve volt system, but when I add Solar I might transition to 24v.

I would caution against this approach. Its doable but not very economical. The Inverter, DC-DC charger, and often the BMS (depending on the model) would need to be replaced if you change system voltage down the road.

Best to determine the voltage you want upfront and make the investment now, so you don't have to spend more replacing components down the road.
 
What do you need 3000W for? I got a Giandel and it's loud. Had to switch the Fan.

I got a 1200W Inverter now - and it supplies all my needs. Just can't run two big appliances at once, have to turn of the coffee maker to turn on the microwave or the induction cooktop.

The bigger a inverter is the more power it wastes in Standby. So get the smallest one you can get by with.
 
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