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Clue me in about portable solar panels, please

In recent months I’ve acquired two “solar generators”  — the MAXOAK Bluetti 150 and the massive Goal Zero Yeti 3000X.  (Hot tip: if you are in Northern California and are a PG&E medical baseline customer, meaning you use some sort of medical equipment and get a special electricity rate for that, you can actually apply to receive a free Yeti 3000X, which normally runs over $3000.)

Now I’m trying to acquire solar panels to charge these batteries. But I know almost nothing about electricity and about solar panels specifically. I have some specs from the manufacturer and some customers on Amazon (listed at bottom), but what else do I need to keep in mind?

I notice different panels are listed as being made of different materials? Does it matter?

Some panels are flexible, which wouldn’t work for setting them outside when I need to charge my generator, but is there a way to attach these to a rigid surface, like a board?

Some of them come with controllers. I don’t know what these are for? I know that the generators come with their own hardware that’s their interface for the panels.

Anything else I should keep in mind? Because otherwise I would literally go out and buy the cheapest panels I can find that meet the specs. Which are:

Bluetti 150
*≈10 Hours (Using 200W Solar Panels simultaneously with full sun)

The recommended solar input for the Bluetti EB150 is 400 watts at 12 Volts. This will fully recharge your unit in around 3.5-4 hours of ideal sunlight.

Solar/AC Recharge: 1)This Power Generator Can be Recharged from the Sun with Solar Panel (Open Circuit Voltage must be 16V~60V(Max),Max 500W,Solar Panel not Included). 

This is the solar panel set they sell, which looks nifty but is way overpriced: https://www.bluetti.com/products/120w-solar-panel

Yeti 3000x

100W (Boulder/Nomad 100 (BC) ): 36-72 Hours
200W (Boulder (BC) ): 18-36 Hours
400W (Boulder 200 X 2): 9-18 Hours
600W (Boulder 200 X 3): 6-12 Hours
800W (Boulder 200 X 4): 6-9 Hours
1200W (Boulder 200 X 6): 6 Hours

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  • Comments (13)

    • 4

      I will post my experience with solar here in the near future.  I knew absolutely nothing about solar but was able to learn a lot by reading on line.  There are loads of UTube videos and information available.  I went ahead and made the investment to get into solar earlier this year.  I’m still working on getting everything installed but do have a working system up and running now.  I will say one thing about it, the most important thing I learned so far.  It is NOT economical.  It is so much cheaper to purchase power from your utility than to produce it yourself.  That being said, prepping is about having multiple ways to ensure your ability to take care of yourself and your loved ones.  Having multiple ways to do that just makes sense to the prepper side in me.  471B5902-8345-43EA-8F55-A93CEBD50E32I will post a series of pictures of my progress in the next couple days.

      • 3

        Just to be clear. I’m not talking about a setup that would power my whole house. Nothing as big or as permanent as what you show there. I’m looking for something I can use to recharge my solar generator from the sun when needed. I use the generator for emergencies and also, potentially, in the future, to go camping. Mainly I need it to make sure my CPAP machine keeps running when I’m off the grid.

        But, since you mention it, for the record, I do have solar panels newly installed on my roof. That was all done by the solar company and contractor. It’s not a DIY project and not my concern here. But, in my area, it IS more economical than getting your power from the power company. We have some of the highest power rates in the country.

      • 3

        You are right about if you do a grid tie system and especially if you install it yourself you can actually break even or a little better.  There is a lot more expense in an off grid system with battery storage.  My system in theory could break even in I think about 8 years, but that’s without maintenance, replacement of parts, and of course the big one is replacement of the batteries.  With that in mind I will never break even.  I also didn’t factor in that the power Bill I’m comparing with runs my AC and heat.  The solar I’m doing will never do that.  At best I could run a small window unit to cool off a bedroom at best.  Even with these drawbacks the peace of mind knowing I can run most things after the grid goes down is pretty good.

    • 6

      Unless you are planning on walking out with your solar generators and panels, which I doubt, why portable?  I charge mine with full sized panels. If you need something a bit more secure than leaning your panel on the side of a building, you can always attach them to some fencing panels or make a brace with some lumber.  I’ve seen online plans for making the structure out of pvc.

      solar

      • 3

        Maybe I’m using the wrong terminology. When I say portable, I don’t mean the kind you can carry in your backpack. I mean the kind that’s not permanently attached to, say, a roof, the kind I can take out and put away as needed and also the kind I could take with me in a car if I go car camping.  I would be fine in principle leaning it against a building, except that the angle you show there isn’t a good one, as I understand, for effective exposure to the sun. But right now that’s not my primary concern. My concern is figuring out what panels to buy.

      • 5

        Depending on your car, you might have trouble getting full sized panels in there but sure you could put them on a roof rack.  The best angle for a panel changes constantly, depending on your location in the country, time of year and time of day.  That is the advantage of leaning panels as opposed to having them in fixed mounts.  Fixed mounts find the best AVERAGE position with those three factors considered, meaning rarely are they in a perfect position for optimized charging.  Often they are constrained by the angle of a roof or direction of the roof.  When you lean a panel to charge a solar generator, you can lay it flat on the ground if the sun is high in the noontime sky or prop it up like I did when the sun is low in the sky.  Optimizing the angle by moving the panel during the day means quicker charging.

        I bought mine several years ago and they are 280 watt panels.  I think the technology today can get you around 400 watts in a similar panel.  I suggest reading reviews and going to different online stores to find the best panels available today.  You just want basic panels.  Certainly don’t need built in controllers to charge a solar generator.

      • 2

        goal Zero recommends their Boulder 200 panel as a good mate for the Yeti 3000 – retail cost is 500 bucks.  Movable so you can adjust the angle to the sun for optimum charging;  https://www.goalzero.com/shop/solar-panels/boulder-200-solar-panel-briefcase/

      • 4

        I bet they do.  I see pricing for panels with double the wattage, 400 watts, for less than half that amount… $225.  If you don’t want to just lean the panel to charge a solar generator, I’m sure most could rig up a frame for very little.

        IMO, if one is just charging a solar generator, I’d go for the most wattage for the least $.

      • 4

        One thing I just read is they are extending the 26% tax credit for two more years now!  It was going to drop for 2021 but is still good now.  That’s a really good discount for a home system.

      • 2

        Right. This is what I’m thinking. But are there any other considerations wrt material, rigidity, brand, etc.?

      • 2

        I was also going to say I bet they do, but Redneck beat me to it. If I wanted to just buy what the manufacturer sells I wouldn’t have started this thread. But their stuff is vastly overpriced so I’m looking for alternatives, of which there are many. I just don’t know which one to choose because I don’t really know much at all about solar panels.

    • 3

      I would try and calculate what you are going to want to run off of your solar generators, and that will give you what size panel/s to get. 

      If you are just doing the cpap machine, that can use around 53 watts or 90 watts if you use an integrated humidifier. Look at the power cable or where the power cable plugs into the machine and you can see how much yours will use. If it doesn’t say how many watts you can calculate it by multiplying amps X volts = watts. So a machine that runs off your normal wall outlet in America will be 110-120 volts, and if your machine says that it uses 0.50 amps then 0.50amps X 120 volts = 60 watts/hour. So you could run this device off of your 3000 watt Yeti for about 50 hours. 

      That being said, you need to look at your battery type in your solar generator. I believe that lithium ion batteries (which both of your generators have Jonnie) can be drained further down than lead acid batteries and the built in circuitry will stop it from over discharging. You do not want to drain lead acid batteries below 50% as that can put strain or kill the battery. 

      Once you know what your usage will be, lets say you want to use 200 watts of power a day, then you will only need to buy a panel that can produce that 200 watts. Always plan a bit more than you think you will need incase there is a rainy/cloudy day. Look at how much strong sunlight you get every day in every season. (there are online solar panel calculators that can help you figure this out)

      I am going to get a solar generator and start out with one panel. I’m going to get the cheapest one that produces the most amount of watts and that is in a form factor that I want. I’m going to look out for the connection types, and the ability to link multiple panels together for increased charging speed and buy one or two more in the future. 

      This all is just what I have learned about solar generators, solar power, and batteries from looking online. I don’t have a solar generator yet, but have been doing research so I can get one someday. Pretty awesome you were able to get a Yeti 3000x for free!