I’m only half kidding. I’m a bit of a prepper and I have lots of powerbanks and devices that charge from USB but besides idling my truck I really had no other way to charge any of them in case of a long-term power outage which seemed a bit of an oversight on my part.
Not like this solves the issue. 30 watts (under ideal conditions) isn’t much but it’s a start.
Be careful. Those things are addicting.
That’s how I started: a little 5v, 6 watt panel I stuck in the window to charge my phone while I worked. Then I wanted to charge some other stuff, so I got a 15W panel. 15w panel was nice, but 100 watts was much better, so I bought two 100W fold-up panels like you’ve got.
Then I bought a big 1 KWh power station that could supply up to 2000 watts. I take it camping and charge it from the two 100W fold up panels.
But, sadly, the demon had its claws in me and refused to let go. “Why should I only use that solar power two or three times a year?” the voice said. So I bought 4x 200 watt panels so I could use the power station to power my homelab and refrigerator during the day.
Still, that wasn’t enough to satiate my addition. Now I’ve got 4 KW on the roof, 32 KWh of house battery, and a 10 KW inverter that is currently powering our house.
Am I satiated now? Only time will tell.
I haven’t heard you say a word about your solar powered electric car…
Check back in 2-3 years when I (hope to) get an EV. I’m sure I’ll be crowing about it then 😆
In the mean time, would you like to hear about my solar powered lawn mower?
Unironically yes haha. I hope it’s just a manual lawn mower that you have your son push around.
That’s a weird panel to battery ratio. Guess you’ve gotta work on that now. Got more room on your roof, preferably south-facing?
Though if there are ground systems that can aim the panels and you have room there, that could be really cool.
The usable south-facing roof area is full, unfortunately. I’ll have to do ground mount in the back yard and run a bunch of conduit if I want to add any more PV.
The 32 kWh of batteries are made of two 16 kWh batteries in parallel. Since this system is in lieu of a backup generator, I have it configured to only draw the batteries down to 50%. That leaves the bottom 16 kWH available for emergency use. Basically, for day to day usage, I treat the battery as being half the capacity it really is.
I’ve only been running this system for about 3 weeks now, but the batteries have been operating between 65% and 90% pretty consistently even running the A/C pretty heavily. They’ve been closer to low 60s this past week, but the wildfire smoke was choking out the sunlight Thursday and Friday.
Have you calculated how long it takes/took to pay for itself?
All of the labor has been DIY, and I’ve got about $9,000 invested in the system components.
Back of the napkin math, at current electric rates, puts my ROI at just under 9 years. If electric rates keep going up, it’ll pay back even faster.
Edit: Depending on how you look at it, ROI could be in as few as 1.5 to 2 years. This system is in lieu of a whole house generator that would have cost us about $7,000. Had we gone with that instead, it would never have paid for itself (other than peace of mind) and we would have been perfectly content. So if I’m only considering the price difference between this and the generator, it’d only have to pay back $2,000.
A hobby pays itself just by enjoying it. I’ve never calculated how long it will take to pay off my gaming rig
If you enjoy it, it already has.
I get you but it was worth the money you spent ≠ it earned back the money you spent.
Okay but for real how long
have battery system and solar since jan 2023, still love it
Time, in hours (H), equals average solar kilowatt hours per month (K), multiplied by the price of one kilowatt hour (P), divided by the total cost © of all the purchased components.
H = (K * P) / C
I’m sure if you were patient and dedicated enough, you could approximate each of those numbers using the info OP has already posted and get a general idea (weeks, months, or years).
So you’re dividing the average saving per month by the total cost and expecting to get hours?
If we generously estimate a very high 3000kWh/month generated and high $0.40/kWh price and it cost OP $9000, then you formula is (3000×0.40)/9000 = 0.133 hours.
Breaking even after less than 1 hour?!??! Extraordinary!
It’s pretty easy to cry about bad math, but it’s a lot harder to figure out the right math.
Don’t worry, I’ll try to do it for you again a second time.
Power consumption varies. Use the average monthly power draw from the solar array, let’s assume for demonstration purposes 1,000 kWh/month.
Multiply that by the cost of 1 kWh from the power company, let’s say 20 cents.
In one month, that means you saved $200.
Let’s assume the solar equipment costs $1,000.
The answer is 5 months, or 5,000 kWh.
Sorry, I’ll make sure the free work I do for you is better quality next time.
Or I could read the comment where he said
Then do that instead of asking random people who aren’t in any position to know.
I recently got a bluetti for off grid onsite work and it has awoken something in me. It’s like carrying a wall outlet around with you, absolutely incredible.
Needless to say I think I have caught the bug. Where would you point a feller who wanted to walk your path and learn more?
I’m more of a hands-on learner but that can get expensive depending on the hobby haha. For going solar, I’m still very much in progress but definitely on the path to where i want to be.
Basically the first step is to decide what your goal is. Do you want to go totally off grid? Just reduce your electric bill? Have backup power? All/some of the above?
If you only want to reduce your bill, check into what’s called grid-tied or “balcony solar”. That’s the easiest to get started with, but it requires cooperation from the electric company since you’re feeding back into the grid. I can’t do that here, so I went with a standalone/battery-based system.
Once you identify your goal(s), you’ll need to figure out what your “base” load is, and then how much your peak loads are so you know what size system to shoot for. Then you’ll need to choose an inverter that can meet those with some extra capacity for unforeseen spikes. I started with a 10KW system, but it’s also expandable up to 60 KW( 6 units in parallel). My house only has 100A service, so two inverters would actually give me more power than I can currently get from the power company lol.
For the panels, you can really only expect to get 60-80% of their rated output most of the time. The rated output is under perfect alignment with the sun, at the perfect angle, and with absolutely no obstructions. In practice, you’ll never see that. As an example, I usually only get between 3 and 3.4 KW out of my 4 KW system on the best of days. This is normal.
For batteries, they’re technically optional depending on your goals. If you just want to shave some money off your electric bill, you can forego the batteries and the inverters will happily mix PV and utility to power your loads during the day. e.g. If you’re drawing 1,000 watts and only getting 900 watts from PV, then it’ll make up the missing 100 watts from utility power.
I sized my batteries based on my average daily usage plus an extra 10 KWh. We use about 20 KWh per day, so I got two 16 KWh batteries for a total of 32 KWh. That means, if there’s no (usable) sunshine at all and we lose power, I can run the whole house for a little over a full day. Any sun hitting the panels will reduce the current draw from the batteries while also charging them if we use less than the PV is producing.
The longest power outage we had was about 29 hours, but if we typically experienced multi-day outages, I might have gone for a larger battery.
I had a much longer reply written up, but it barely scratched the surface. So hope this helps in a general sense but happy to answer any specific questions if I can.
Thank you for the primer! I find it very interesting and you’ve certainly given me plenty of things to research and learn more about.
I think my biggest goal is actually power stability but the cheaper power bill would be a welcome bonus. In my new shop the table saw seems to trip it’s little built in circuit breaker a lot more often when it is cutting thick hardwood than it did in my old shop. Unless the blade is sharp as shit resawing on the table saw is a distant memory lol.
I think it’s because the run from the road to the house main is a long run and then from the house main 60 amps is routed out to the shop which is another long run out to the shops breaker box. Then from there I use a 25 ft 12 awg extension cord to power the saw and dust collector via an automatic vacuum switch. The saw very rarely tripped at the old house when the total run from the road to the saw was less than 50 feet and I never did it any favors. But now that it is hundreds of feet away from the source I think the voltage drops off and it over heats and trips the sawstops little breaker.
I hope that made sense, I’m a carpenter not an electrician lol. What I think I need is a battery set up for the shop that acts like a giant Uninterruptible Power Supply to combat the “dirty” power and put the saw closer to the source. The ability to power a hybrid solar/dehumidifier kiln in the future from the shop without sacrificing power reliability would also be something I would want to consider.
Thank you again for the write up on your setup!
I got the power station first out of necessity, but am now at the point of desperately trying to justify adding solar panels even though I don’t camp or anything. I fear it could become obsessive though.
Maybe I keep can limit myself to only as many panels as I own violins? That would be a fair number… Or at least cap it off at the number of musical instruments in the house? That would leave some room to grow, if I can count my wife’s ukulele collection!
Lol, def can become an obsession. First hand experience there.
I’ve wanted a whole house PV system for a long time, and this is just me finally getting around to making it happen. SO and I were talking about getting a backup generator installed, but that would have been about $7,000 for something that would only get used two or three times a year since our power doesn’t go out often (we have no heat or ability to cook when the power goes out, and it’s always in the dead of winter when we lose power). The PV system I sketched out was about $9.000, but in addition to covering us during outages, we could use it daily to reduce electric bill so, unlike the generator, this would pay for itself over time.
SO finally came around to my way of thinking, so here we are lol. My limiting factor is usable roof area. Of the roof that’s south facing, only about 14x20 feet of it is suitable for mounting panels. There’s a west-facing gable, but it’s blocked most of the time by a tree. The east-facing side of the gable is available, but it’s pretty much always foggy in the mornings here, so it wouldn’t add much to the system.
Unless I build a ground mount setup in the back yard, we’re pretty much at the limit of how many panels I can buy. I’m kind of glad for that because otherwise I’d just keep buying them.
I keep thinking about this. I can’t justify solar when I live in a northern country and pay about $0.06 USD/kWh, but the value of resilience also counts.
😭 The per-kilowatt hour rider fees on top of my base rate per kWh are way more than that lol.
Im “lucky” enough to live in a region with abundant hydroelectric power. It’s still cheaper to heat your home with natural gas here…air source heat pumps might get close when they work.
UNLIMITED POWER!
🤣
I’ve been looking to get a so-called “Chinese diesel heater” to my shed to keep it warm over the coldest days in winter when electricity is very expensive and the two small radiators designed to only keep it above freezing can no longer keep up. However, those run off 12V DC and power supplies seem to be surprisingly hard to come by. Easiest solution would be a car battery and a trickle charger but I’ve thought about just setting up a tiny solar system instead because then I would have a kind of off-grid location to fall back to. My house doesn’t have a fireplace either but the shed does (sauna). This would also allow me to charge all my tool batteries that require a standard outlet.
For heating, I’ve been wanting to try a solar collector. Not sure if you’ve come across Greenhill Forge on YouTube or anywhere that covers his projects, but he does all sorts of off-grid stuff.
https://www.youtube.com/watch?v=8cPuVZjnbi4
That’s where he builds and tests several different styles of solar collectors for solar heating. The collectors are pretty inexpensive to build so that may be an option if you just want to (help) keep a shed warm.