Charging Behind A Patio Door

We just purchased a Bluetti AC200P for storm backup. Our only option as we are in a high rise condo. We can count on losing juice 3 times a winter. We have 3 large glass panels that are exposed to 4.5 hours of direct sunlight and can only get better after the shortest day coming up in December. I know the capacity of a panel will be greatly reduced behind glass. I need light weight flexible panels to hang in the windows because I do not want to drill anything into the frame. This will all be removed in spring. I have gotten some results as an experiment by placing a 100 watt foldable Jackery panel on the floor to charge my Jackery 1000 over a few days. Panel of course had obstructions from the sun by the frames of the door. The panels I will hang will be free of obstruction. I have thought about hanging two or three 200 watt flexible panels. I doubt they will exceed the input of an AC200P. Can I use these panels for the AC200P and should I not have panels with built in controllers. I know the Bluetti has its own controller. Even if the partially help with a charge, I would not depend on it long term. Worst case is, I remove the AC200p to my shop for recharge. If the juice is out there too, I can run my gas generator there. I hope this makes sense, I kind of know what I’m doing but I don’t. The sun on the patio doors which I curse in the summer just seems like a lot to leave unused in this situation.

Welcome to the forum!

I’m not entirely sure what you are asking, tbh :sweat_smile: but if you’re thinking about buying flexible panels, please be aware that they cost a steep premium. So if I was in your position, I’d try anything I can to make do with one 420+ Wp or two 350Wp rigid solar panels, no additional MPPT controllers required. They are not only cheaper but also more efficient.

Maybe you can store them under your bed or behind a closet during summer?

Great choice for condo. Should serve you well during outages. You could even expand with a B230 battery if you fid you need more run time. Cheers

Thank you Winnie. I like the rigid panels but concerned about the weight. A frame would need to be built to support them which I could do but would just be disassembled and stored in the off season. Storage is not an issue. I am learning that I would need a minimum of 35 volts and accounting for the losses behind the glass I’m going to take a wild guess and would be looking at between 450 and 600 watts of panel. Rigid panels are a whole lot less expensive as you said and I like that considering the prices of the flexible panels. Thanks again and Happy Thanksgiving.

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Thanks for the heads up Woody, I was not aware that this could be expanded. That changes things a little bit. Happy Thanksgiving.

I am curious what kind of power output you saw in your 100W Jackery panel experiment with full sunlight through your window?

Ben, to answer that I would need the numbers from that and I did not pay to much attention to that. The reason being is that I had only had it a few days and just wanted to see if it indeed received anything at all. After testing the Jackery on appliances to learn what to expect in terms of what it would run and for how long, I just wanted to see if it would charge at all. Then I moved it to my shop to test it there on tools, and appliances including deep freezers and 12 volt Alpicool coolers. Again I used one 100 watt panel and painstaking slow. If I use solar to charge it again, I will use the two 100 watt panels that came with it. I could only use one here at home because there was not enough room in front of the windows as it had to be propped up on the foldable stand. I know this does not answer your question but I feel any charging done through the glass will need to be from panels mounted or hanging close to the glass and input nearly double that recommended. Were I to be charging the Jackery 1000, I would be looking to use 2-3 100 watt panels for a closely watched 1-2 day outage. Mainly for the refrigerator and an over night electric blanket. I have not had an outage as yet, and in that event, I will use the Bluetti, but would not have an issue using the Jackery either. Sorry about the lack of numbers, I am new at this. i am looking more at the numbers now because I learned that is what everything is related to with these things.

I see. It would be nice if you update here when you try again. Just curious. Thanks!

Here in Germany, we have loads of so-called “balcony power plants” with specialized mounting solutions. Maybe that can serve as an inspiration for finding a spot for your solar panel outside your high rise building and a specialized provider for mounting solutions in your area…?

I’d be amazed if you got anything worthwhile through the glass (and I’m not saying that as any kind of expert - just my gut feel). I guess I’m basing it on campervan trips where I learned you really did need to put the panels on the windscreen - not inside.

What about sticking flexible panels actually on the outside of the glass? I’m not sure how, but there must be some way to do this?

It has been my experience that it is very possible and has been done. I’m not trying to put lipstick on a pig here and have stated that the solar capacity of the panels would need to be nearly doubled from behind glass. Glass is not impenetrable but deflects. Much as we look for the proper angle from the sun outdoors that same proper angle would be deflected away from optimal through glass and that deflection is the part we can not recapture. Aside of deflection of direct sunlight a certain amount is also lost in overall reflection. The question now becomes how much panel can I expose to available glass? In my case I have a maximum of three times the suggested amount need to charge any of these units that I have. A windshield from the inside could not approach the area needed for even the smallest generators. I had some ideas on front and rear panels cut to match the dash and rear panels in an automobile but that is a different story and would require outside sources. Solar does charge a small outdoor landscape light in the rear of my car and also will charge my battery pack for recharging phone etc so it does work. Just not enough to provide sustainable energy for a camper, survival or similar situation.

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Thank you. I will look at any ideas however nothing at all can be mounted outside on my balcony. It is in the Commie by-laws of the condo association and agreed to follow when I purchased the place. Its nice but living so close to others has its drawbacks and this is one of them.