diy solar

diy solar

Complete newby to solar - seeking suggestions for small portable system that can be expanded

cbc59

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Joined
Feb 17, 2023
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Location
North Carolina
Hi - As the title says - I am a complete newby to solar and have watched many videos on small portable solar builds that people have made using a plastic toolbox and some components. Everyone seems to do things a little differently and I know that there are all level of components out there.

I would like to ask - if you were building a good quality portable system that could charge phones, run a portable fridge for camping, some lights and a laptop or two... what would you use? The main question relates to expanding such a system if you wanted to add more power down the road - maybe a couple of more batteries and panels.

What I am trying to avoid is building a small portable system - and then having to scrap everything in it to build something bigger down the road. Any info is appreciated.
 
What I am trying to avoid is building a small portable system - and then having to scrap everything in it to build something bigger down the road
Have you done an energy audit so that you can size the system properly the first time?

Getting the number of watt hours you expect to pull from your system each day (or before needing to somehow (?) recharge) is what you need to calculate.
 
Fridge… 2kWh average daily…
Laptop depends heavily on amount of use… but a 60W low power laptop running 4 hours will be around 240Wh
Lights, again, depends on brightness and quanta, but figure 30 watts, and you have 240Wh in 8 hours…
 
Blurb time!

Well, I'll start the default answer to these questions and we can work from there. Here's you To-Do list:

1: Power audit! This will give you some important information on how big your inverter needs to be as well as how much battery capacity you'll need. There is a link in the FAQ section (I think, or someone here will post it shortly) so fill in the blanks and see what it comes up with. You'll probably need some sort of Kill-A-Watt to get accurate measurements. Are you going to be running a 12v system? 24v system? 48v system? What are the specs on your solar panels? VoC? Vmp? Being as this is a new build, throw together a wish list of what you want and estimate on the high side.

1a: Where do you live? Speccing out a system for Scotland is a LOT different numbers than Arizona due to the amount of light you actually get. Someone here can post the link to the PVwatts.com or JCR Solar Uber-Sun-Hours calculator sites to help figure out how much you'll have to work with. That will be a box in the Power Audit form.

2: Parts list: You don't need a make & model list, just a parts list to start from for reference. You'll need an inverter, a MPPT charge controller, fuses, shunt, buck converter, batteries, wire, etc. Once you have a basic list it can be fine tuned to make & models after that. If you're looking at the All-In-Ones check for correct voltage outputs (120v or 240v Split Phase for North America, 220v Single Phase for European type areas) and make sure it has enough capacity for a little bit of growth and fudge factor.

3: Budget!: Steak is great but doesn't mean anything if your wallet says hamburger. :) Figure out what you're able to spend now vs what you'll have to cheap out on now and upgrade later.

4: Tape measure! Figure out where you're going to stick all the stuff you'll need. A dozen 3000AH batteries sounds great until you're sleeping on the floor because there's no room left for a bed. Is there a compartment that can house all this stuff? Will the server rack batteries fit? Are you going to have to make space? Physics can be pretty unforgiving.

5: Pencil out what you think you need and throw it at us so we can tell you what you've missed (because we ALL miss stuff the first go-round :) ) and help figure out which parts and pieces you're going to want to get.

Well that's the thing about solar systems, there is no 1-Size-Fits-All answer. Your system will need to be designed to fit YOUR needs. When you design and built the system, it's not going to be the perfect system for me, or Will or 12vInstall or anyone else, but it Will be the right system for You and that's the goal.

As for where to get started, let me throw my standard blurb in here to help point you in the right direction. There's going to be a lot of math and research involved, but that's going to be a LOT cheaper than just buying parts off of someone's list and finding out that it doesn't do what you need.

Don't panic on the Power Audit, you'll actually be doing that a few times. When you do the first pass put in ALL the Things that you might want. AirCon? Sure. Jacuzzi? Why not. MargaritaMaster-9000? Go for it.

The second pass will be the "I Absolutely Need This To Survive" list that isn't going to have much on there.

The third pass will be the "This is what is realistic" audit that you'll use to design the rest of the system.

The Power Audit is going to tell you 3 primary things: 1: How big does your inverter need to be to power your loads? 2: How much battery bank do you need to last $N number of days with krappy weather? and 3: How much solar panel will I need to install to refill those batteries in a 4 hour day (the average usable sun hours rule-of-thumb).

Once you know what you Want and what you Need and what your budget can Afford there will be somewhere in that Venn diagram where those three things meet.

After that, THEN you can start looking at parts.

Yes, it's a long drawn out process, but it's worth it in the end. Not every house has the exact same floorplan, not every vehicle is the same make & model, and not every solar system is designed the same.
 
It depends on if you are approaching this as a learning experience or have a definite goal. Small systems (especially portable ones) are of limited use. They can provide you with experience in how the various components work and what you can expect from using the sun as a power source. But they are not really all that expandable or reusable. If you start with regular solar panels you may be able to incorporate them in larger arrays as time goes by (This I have done with my own solar journey down the rat hole). However things like matching panel specifications for voltage and wattage can trip you up.

By and large you can go for a designed goal or you can wing it knowing that what you start with is not what you will finish with years from now.
 
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