Solar + power bank for household appliances in apartment - can I reduce my electricity bill?
Comment box
- Scope: exploring a wacky idea
- Tone: being open-minded
- Opinion: none
- Sarcasm/humor: a couple dry jokes
I watched the video "Dirt-Cheap Solar Generator Setup - What Can It Power?" by Alex Beale yesterday. In the video, the presenter purchases a cheap solar panel and power bank for a total of $250 and tests household devices to see what kind of wattage it can take.
Turns out the cheap device can power most household objects. I'm curious if it's possible to try a similar setup to meaningfully cover my electricity usage on a day-to-day basis. Unlike the creator of this video, I don't have a yard. I'm exploring whether a solar solution could work with my constraints.
I wanted to share this idea with Tildes and hear any ideas/feedback/experiences from people who have tried something similar.
My goal
- Investigate whether it's feasible to save money with this setup
- If so, find a setup that I can use to power some or all of my household devices off-grid
- Pay less in electricity costs
- Be able to rely on my power bank when the building's power goes out
My current situation
- I live in an apartment in an urban area in the US northeast (southeastern Pennsylvania).
- I do NOT have a balcony (sadly).
- I have two south-facing windows and four west-facing windows (two of which get a LOT of light, two of which get a decent amount but not as much). However, my south-facing windows don't get direct sunlight most of the day since there is a building in the way (just a bit in the late afternoon).
- The dimensions of the windowsills are about 16 inches in depth and about 55 inches in width. That's enough for a small or medium-sized solar panel, but not most panels designed for outdoor use.
- I can open the windows all the way and it would be physically possible, in theory, to hang something outside rather than keeping it on the windowsill (we'll get into this...)
- I pay for all my electricity. The heat/air is central and inaccessible, as are a couple of the overhead lights (there are only a couple), but everything else could theoretically be replaced with energy from a power bank, I think.
- I already have a power purchase agreement with a renewable energy supplier. All my energy is "green" in the sense that I'm making it slightly more economically feasible to produce green energy.
- In a less expensive month, the bill might come to around $75. In an expensive month, it might come to around $350. If I heated the unit as much as I would like, it would be higher.
- I'm pretty sure most of my electricity use is the heat/AC.
- I'm pretty sure most of the remainder is the
washer and dryerdishwasher, followed by the washer and dryer. - I spend some amount heating my water otherwise (shower, sinks), but I can't address that with a solar panel.
- I wouldn't mind saving money on the rest if that's all that's feasible.
My power needs (I think)
- I don't know much power my oven uses. It's electric, which the internet says averages around 2500 W.
- My dishwasher runs at 120 V and 18.7 A. That is... uh... 2244 W. Also a lot.
- My dryer says 120 V on the machine, and if I look up the model number, it seems to be at 15 amps. So that's 1800 watts.
- My washing machine, uses....... IDK how many watts. No information on this thing exists. But it uses a 120 V outlet. The internet says an average washing machine could use up to 1400 W (sounds high, but okay).
- My computer has a 520 W power supply, but I doubt it ever uses that much. It's old and mostly runs Solitaire. Maybe one day I will get a fancy new machine that does like 1000 W.
- My fridge uses 115 V at 4.5 A. Let's pretend that's 120 V and say 540 W.
- I can't tell how many watts my TV uses, but the internet says it could be up to 200 W.
I would want a bit of breathing room with the rated wattage so that the power bank doesn't explode.
No way I can run all these devices simultaneously off the power bank, but perhaps I could time them. Even partial coverage could be adequate if it makes financial sense.
Possible spatial configurations
I see a few possibilities here:
- Stick a bunch of solar panels in the windowsills, propped up at a suitable angle.
- Stick the panel directly in the window like an air conditioner. In this case I would want to use a two-sided panel, since there would be some ambient light coming from the inside. This would inevitably reduce my home's energy efficiency, which I would have to account for.
- Weld some sort of counterweight to a mounting system that I can use outside the window to perch the panel at an ideal angle. This would also reduce my home's energy efficiency, but maybe by less since the gap could be minimized. It is also probably illegal. And dangerous.
- Just fill my living room with solar panels. I will need to have a conversation about that. But it could be done.
I think #1 is the only one that is actually reasonable. #2 would cost me too much in heating bills to make any sense. I think #3 would get me evicted or sued by the city. And #4 is unreasonable considering that I like to use my house to live in.
My budget
I would maybe spend $500-1000 on this if the payback period was a few years. Not more than 5 because panels by then will be a lot more efficient.
I guess I could spend more than that if it makes sense. I have good credit and a high credit limit. I don't make that much money but I could save for a bit or carry a balance for a bit. I think I would draw a hard line around $3000.
The power doesn't go out here too often, so that isn't the main selling point, more of a nice-to-have.
My research
I'm just looking on Amazon. I know I could maybe get something a little cheaper elsewhere. I'm searching for "power bank with solar panel".
- 4000+ W range: OUPES Mega 5 for $3300+ with panels (I think?). That's a lot of money for something that might not even work. And I don't believe it would be $3300, most other models I'm seeing are closer to $5000.
- 2200 W range: Jackery Explorer 2000 for $2500 with the 2 panels. Maybe this could cover my energy-intensive appliances, one at a time. Still expensive. The solar panels will... maybe fit in the window with about 1/2 inch to spare? I could angle them slightly if needed?
- 1800 W range: (maybe) Anker SOLIX C1000 for $800 with 1 panel. It also says 2400 W so idk what it is really. Can't determine the width of the solar panel.
- 1000 W range: EF ECOFlow River 2 for $700 with 1 panel. I am also not sure how big the panel is.
- 600 W range: SinKeu Portable Power Station for $230 with 1 panel.
- 300 W range: Marbero Solar Generator for $230 with 1 panel.
I'm discovering that these companies never specify the dimensions of the solar panels because they assume no one would ever use them indoors. Probably for good reason. If they don't fit horizontally, I guess I could stand them up lengthwise.
I'm sure it would be possible to find a cheaper solar panel separate from the power bank. But as a ballpark, those are my initial numbers.
Math
Imagine I spend $2500 on the 2200 W Jackery model, with 2 panels. I could put them in the two bright west-facing windows. Let's just pretend they can get their maximum output and that charging time isn't an issue.
Let's say I use this every time I run my oven, dryer, washer, or dishwasher (not at the same time), and otherwise I connect it to my fridge and most other electronics. (I know I said my oven could be 2500 W, but I usually just use one burner, and I bet that's more like 1500 W.) Let's pretend the hassle of running all those cables has been solved somehow.
I really don't know exactly what my electricity breakdown is. If I have the heat/AC mostly off and am not in the unit a whole lot (e.g. traveling for some of the month), that's when I end up with a $75/mo bill. But if I'm out of the unit, that means I'm also not using my dryer/washer and other devices as much. I guess the fridge was still on. The $350 side of things is because it's hot and I'm running the AC more, and maybe slightly higher dryer usage for some laundry-related reason. So maybe I'll say the minimum I'm spending on non-heat/AC electricity per month is $50-100, and at most maybe something like $150.
So in this super optimistic scenario, the portion of my monthly electricity bill I suspect I'd be able to theoretically save would be $50-150. Let's just say $100. That means it would take 25 months to pay back if all goes well. Honestly that's not so bad.
If I instead bought the 1000 W ECOFlow setup for $700, I could cover all my non-intensive electrical uses. The main beneficiary would be the refrigerator, the computer, and maybe the television. I think the savings there would be like $25-50/mo at most, being pretty generous. If I say $35, that would be about a 20-month payoff. That's also pretty good, but if it'll take about the same amount of time to pay for itself, I'd rather get the higher-wattage one.
Numerous caveats:
- It's not always sunny in Philadelphia.
- The panels will not be at 100% efficiency because the window is cloaked in shadow half the day, and there is no way I get the angle perfect, and maybe the glass affects how much energy they can absorb or something (would it help? hurt?). This isn't inherently an issue, except...
- ...that the charging time for the power station might be long. Some of the reviews say 6 hours in maximum sunlight, so for my use-case there's no way it would be faster than 12 hours for a full charge, and probably more. I use my appliances kind of a lot. The fridge is always running, and either the washer, dryer, oven, or dishwasher are running a pretty good chunk of the time. I think that I could get by with this... but I probably wouldn't be able to use it as much as I'd like (there are often moments where more than one is running simultaneously), so...
- ...the payoff time wouldn't actually be 25 months. I suspect there are some factors I'm not thinking about that would reduce the realistic amount of energy I'd save here. Let's say it is half as effective in my setup as a normal person's, because the sun is half as visible or something, and the charging time is too slow to use often, or whatever. At a 50-month payoff (4 years), I would start to get skeptical. But not inherently opposed.
- I use my windowsill for other things that like sunlight, like plants. I would have to move the plants that really love the sun somewhere slightly dimmer. Is it worth it???????
- I also like to look out my window, and if I had a huge solar panel there (especially if I had to stand it up vertically for space reasons), that would be a bummer perhaps.
- Constantly charging and discharging this thing probably reduces its effective wattage output fast. I.D.K. by how much. But there might be a point where I can't use it for my high-wattage devices, which would largely defeat the purpose of buying an expensive model. Not clear to me what the timeline for that would be.
- I still can't figure out if the panels would actually fit in my windowsill.
- Since it wouldn't be able to run more than one energy-intensive device simultaneously, I'd have to be careful not to keep it plugged in to too much stuff at once. It would overall be a bit of a hassle to plug in the panels and the charger and everything. Maybe the panels could stay plugged in, but even so.
- Running extension cords all over the house and putting a giant solar panel in even just one or two of the windows would result in a catastrophic domestic state of affairs. I can just imagine the eye-popping that would happen if I set that up unilaterally.
Takeaway
There is almost definitely something I am not considering. My math is so napkin-based, so imaginary and so optimistic.
But even if the practical efficiency isn't great, I feel like this could maybe possibly actually work, and could save me a bit of money. I would just have to spend it all up front. I mean I don't have $2500 on hand. But I could scrounge up part of it and put the rest on credit. And it would make for living room conversation with guests?
Realistically this seems like an amusing but too-annoying to actually do sort of project. If you know anyone who's done something silly like this and had it work, let me know! I'd be curious what their experience was.
Sorry to be a downer but the maths just doesn't work. The Jackery system claims to be 400W of generation. Assuming they're telling the truth, that's going to be in absolutely ideal conditions, full, direct midsummer sunlight, perpendicular to the panel. Behind a window in the shade is a long way from ideal. If you are lucky you might get half that. So you're looking at 200W max output, at which point you need over ten hours of full sun to charge the battery at an absolute minimum. I'm not sure how things work exactly at your latitude but while you might get that a few months of the year, you definitely won't for lots of it. For comparison, my roof mounted 4kW solar array only averages over 400W for about 2/3 of the year, but I am a bit further north than you so the winters are darker (although the summer days are longer). Right now, a few hours after sunrise on a kinda cloudy day, I'm barely getting 100W out of it!
I don't know if you can get variable rate electricity but if you can, some smart plugs and timers might be a more workable way to save on power bills. Run your dishwasher and laundry at night when the power is cheaper. I pay 44p/kWh during the day but only 13p/kWh at night, so this is what I do in the winter, as well as charging the house battery from the grid. I save some money by doing that in the Dark Times, but I have appliances with timers on and I have 5kWh of energy storage already wired to my house supply.
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If a 400 W output manages a 6-hour charging time (as reviews indicate), a 100 W output would be a 24-hour charging time.
Realistically, that means 2 days in the summer and 3 days in the winter for a full charge, more or less. I agree that the benefit is muted in this case.
My dryer cycle takes well over 1.5 hours, so the power bank would only be able to do part of that. It could individually do the washing machine, oven, and dishwasher just fine, I think. But then I’d have to wait 2–3 days for it to be full again. Other than wash/dry (which I’m not waiting 2–3 days to finish), this is okay, but still a reduction.
In practice, I think this would mean coverage for my washing machine and dishwasher, and maybe some smaller appliances. Optimistically, that could be 50% of my replaceable energy, and probably more like 30%.
Financially, if my theoretical replaceable energy is $100/mo, and my actual replaceable energy (with this unit) is $30/mo, and I make use of it consistently, the payoff period would be 83 months. That’s about 7 years. Seems questionable. Not sure I care enough to save $2500 across seven years.
PECO offers variable-rate electricity. I’ve used it in the past. While annoying, it has saved me money. However, I chose to switch suppliers to a company that provides green energy exclusively.
This is a philosophical/moral decision a not a financial one—I was and am willing to pay more money to specifically exclude paying a natural gas company to burn fossil fuels.
Unfortunately, even though PECO still delivers my electricity, I’m not allowed to use a variable-rate plan if the supplier is green. My green plan is something like 50% more expensive than my variable-rate plan.
It's almost certainly less, I'm afraid. Solar intensity is considerably lower during the winter, even as (relatively) far south as you are. If your panels can do 100W in high summer you'll get maybe 50W in the winter. For less time during the day. I'd be amazed if you managed a charge in 4-5 days when you're on the dark side of the equinoxes.
This is my average solar array output over a year. Bear in mind this is a daily average output and quite a lot of the day is actually night. Also there was an issue with my inverter so june/july are a bit lower than usual. But it shows how drastically generation drops off in the winters. Your graph would be somewhat flatter than mine though, I expect. Lower peaks but higher troughs.
It is probably worth factoring in the energy cost of producing the panels and getting them to you, and the same for the battery. LiFePo is good chemistry for longevity but the production cost is pretty high. You're probably looking at several years just to break even on the carbon cost of your setup.
You could probably save a decent chunk of power by optimising your power use rather than throwing hardware at the problem. For example, getting a clothes rack and a dehumidifier (or just a window and a DC air circulator) than by trying to run your drier off batteries. The US in particular seems to really like powered clothes drying and it's a terrible waste of energy. Wet things tend to want to get dry all by themselves, you just need to let them. I have lived 30+ years of my life in one of the wetter and more humid countries in Europe without a powered drier and it's never been much of a problem, even when Kid was in disposable nappies which meant the washing machine pretty much didn't stop.
Yeah, probably. None of those devices run at their rated power constantly. My dishwasher mostly sits at a couple of hundred watts with occasional bursts at 2kW to heat water or drying elements. I can't remember how much power it uses for a full cycle but I'm fairly sure it's less than 1kWh. Similar for the washing machine. Oven likes more power but again, it's not constant. You can mitigate power use there with things like air fryers and rice cookers, which are generally smaller and better insulated so you waste less heat.
It's well worth getting some power monitoring before you invest in any hardware though. Then you'll know a lot more what you need. You can get some nice smart plugs running Open Source stuff like ESP32 or Tasmota which will let you graph your power demands over time.
I have eleven 400W solar panels on my roof in southern California, facing SSW with no shade. I figured I could make a calculation based on my generation to see what an upper bound might look like for you.
This past year, January was my worst generating month with 395 kWh, and July was my best with 762 kWh. Let's start with the low, and we'll just double to estimate the high when we're done. That's 35.9 kWh per panel (assuming you also get a 400W panel), and 1.16 kWh per day.
Google's Project Sunroof says I get 1927 hours of usable sunlight per year, while a random location in Philadelphia gets 1580 hours, which adjusts that figure down to 0.95 kWh/d.
You'll lose roughly 15% from charging and discharging a battery, which brings you down to 0.81 kWh/d.
You'll lose at least 30% from charging through a window, which brings you down to 0.57 kWh/d.
I don't have enough information to account for position and shade from your windows, but it's probably going to make a big difference. Let's just round down to 0.5 kWh/d for now.
We end up with an estimate of somewhere between 0.5 - 1.0 kWh per day of usable power. Looks like PECO is selling electricity for $0.09244. If you add 50% as you mentioned, you're looking at generating about $40 worth of electricity per year.
If you can scavenge all this stuff for free, including all the power cables you'd need to facilitate all this, it might be worth it. Otherwise, it would have to be just for fun.
Hey, I'm in a similar situation, down to the lack of a balcony. I have a whole-home, per circuit power monitor, and I think your assumptions about where you're consuming energy are unlikely to be correct:
The common theme here is that the power use doesn't matter -- the energy draw, which is power multiplied by time on, is most relevant for most rate plans on most electric bills. Here's what I'd suggest:
Agree with this. OP, you need to understand your usage accurately, then make adjustments. You can likely make a significant difference without investing a lot of money. Solar is fickly without a good setup so you likely wont have a ROI on this.
I have no experience but I am super interested in this topic. I've been wanting a back-up solar generator that could run our well pump in an emergency. I've looked at the Anker stuff and read some pretty positive reviews but would love to see what anyone who has done something like you are looking for would be fantastic.
First, buy a Kill-a-watt meter or similar and get an idea of how much power any of your appliances actually consume during a 24 hour period.
Then pick one that would make for a good test. Reasonably important, near a window, not too high a power requirement. The sun only provides so much energy, and you can look up what that might mean with a standard 1.6 m² solar panel here.
But it's really just around 1 kWh per day with a 1.6 m² panel. I have a suspicion that a 1.6 m² panel may be out of the question (or maybe not, apparently, but anyway), so let's do half of that and get 0.5 kWh out if it. Now, if we can get about 1 kWh of battery storage, we can run that device off the sunlight, off the grid, reasonably reliably, for a long time. I kept looking for anything that looked remotely like affordable battery storage at this point for so long that I lost my first post. You are on your own here, friend.
Assuming about a 20¢/kWh in residential supply and delivery charges, I believe that system will save about 10¢ a day, $3 a month with that system in reduced electricity, when the weather cooperates. At this point, you can just scale this up to the amount of solar panels that you want to buy.
Does that seem right?
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The math makes decent sense to me. And I’m sure I could find cheap solar panels to scale this up to all six of my windows (in theory). It seems like the expensive part of the package is the power bank for sure.
If I assume 1.6m2 in 6 windows, that could be $3 x 6 = $18/mo… LOL. I think that seems pessimistic, but maybe it is just realistic. If that’s all the savings are, I wouldn’t want to spend more than like $750 on the panels+bank in total.
Based on the video, that might be possible, but i doubt I could find a cheap power bank that could deliver enough wattage to run most of my heavy appliances. But that’s probably not an issue, I’m sure I use $18/mo on things that aren’t my dishwasher.
Anyway, good to know the generation statistics! In my original post I was calculating savings the opposite way, leading to a rosier number. Useful to have two estimates.
I probably couldn’t get away with using all 6 of the windows for this, so I’d need something more efficient. I guess I’ll check back 12–24 months from now. I’m sure the cell technology will have meaningfully increased in efficiency by then. Prices might not trend in the way I hope, but we’ll see.
For context, we live in a single-family house in the same region as you. We installed rooftop solar last year and, while I do enjoy having solar power, we are not saving money at this point. I don't think we will be saving money for another 9 years. I don't think the system will pay for itself for another 7 years after that. I don't think anyone will save much money, if any, for any solar right now, low solar panel prices be damned.
If energy prices go up, it will shorten the payoff period, but if solar takes off, the price of power will fall (good for you) and lengthen the payoff period (bad for us). Ultimately, I'm glad that we have something to provide power in the event of another heat dome/heat wave, like we did last summer. The grid held and no one in the area got a brownout, but they were issuing warnings about the possibility. Next year might not be so lucky.
If we can stay cool next summer, it will be money well spent.
I'm not one to tell another person how to live their life, but just be careful with this. Credit is not inherently bad (in fact it can be a great thing that saves you tons of money) but it's very easy to make a mistake that costs you a few hundred or even a couple grand more than you were expecting. I don't have as much experience on the solar side of things (though I am interested as well), but speaking purely on the financial side of things, those two statements are both worrying unless you really know what you're doing. I say this not to be discouraging, but I would definitely focus on getting results from a smaller budget first so you can have some concrete math to base your purchasing decisions on, think of it like a proof of concept. There's always some unexpected factors when trying out new things, so best to find out after spending $250 that you already have rather than $2500 on credit.
Good luck! And thanks for sharing that video, I enjoyed it too.
One more dimension to consider is your lease. It would be worth a careful read. They may have limits on what you can put in your windows, or other limitations of changes that affect the "look" of the property even if they are temporary/undoable.
Most US residential AC circuits have 15A breakers and are rated for 1500W of continuous draw with a higher spike/inrush current. This is why electric space heaters, big or small, are all 1500W.
So you can assume anything that plugs into a conventional plug is not going draw more than 1500 w and spec a power bank accordingly.
However, if you have an electric dryer, it is probably a two-phase plug and you probably can't power it from one of the lower wattage power banks. It looks like the Oupes Mega you linked has a 30A single phase output, but the others don't. Regardless, I would look at powering smaller/lower power appliances rather than the dryer.
This home depot article is a good primer.
I hate to join in the chorus, but there's almost no way for you to do this cost effectively. I'm fairly familiar with your area, and I now live a touch further south in NJ.
I can say with some degree of certainty that with your available direct sunlight, your payback period is going to be long. You could maybe get 2 functional 200W panels in that space. In ideal conditions, southeast PA gets about 1,350 hours of usable daylight a year. Based on what you've described, you're lucky if you'll get 800. And of that, you're looking at nowhere near rated capacity of the panel most of the time, partially because most windows block a lot of solar energy. But also because you're not getting much direct sunlight, and most panels don't produce even a fraction of their rating from indirect. And anything that sacrifices thermal efficiency of the apartment will negate any savings.
I have a 15KW solar array on the roof, with pretty close to ideal positioning. I only produce at peak capacity for about 4 hours per day in the summer. In the winter, I might get peak capacity for an hour if I'm lucky. If I assume that you get 400W of total capability, and that on average you'll get 100W per daylight hour (again pretty generous given everything stated), you're looking on the order of a total generation of 80 kWh per year. If you're paying on the order of average PA electric rates ($0.15/hr), that's $12 a year.
One of these systems can totally pay for itself, but sadly not in your current living situation. If you had access to a roof where you could get 4-8 panels up and running with access to a lot more direct sunlight, the math would look tremendously better.
I own the Ecoflow river 2 pro that you mention and it is great for my purposes (keeping essential appliances going during extended power outages), but I don't see how you can realistically achieve your goals here without at least a balcony with good direct sunlight. As others have mentioned, the power generation from the solar panels listed is in ideal conditions. Usually you're getting about 60-70% of the stated power generation just due to normal weather conditions even when it isn't cloudy/rainy.
I have thought seriously about your exact scenario a bunch, and I own a home and can leave the panels outside, but it won't ever be as viable as on roof panels like I had in my previous home.
By chance, do you own the apartment or are familiar with the owners of it? If solar power is of interest to more than just a few people in the building, you might get more bang for your buck by putting together a business plan for putting solar panels on the building’s roof.
The logistics and feasibility of that differ a lot based on your living situation; if you’re talking about a four storey walk up, you have a much better chance than a forty storey tower downtown.
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I rent, but it’s not a large building. Good idea!
I say, do it for fun. Buy the cheapest panel and cheapest battery and experiment. If you're into tinkering in general, the experience would be its own reward, and you'll have experimental data to improve your theory making.
At least that's what I would do if I was in your place. I enjoy leveling up practical skills :)
You can get solar managers for raspberry pis and some small panels for experimentation, they're great!