Tip to OP (I think they already have this idea, based on the post): when that lead-acid battery dies, replace it with a LiFePo4, which is substantially more efficient, lasts 3x as long, has a higher energy density, provides a usable voltage far further into its discharging %, etc. etc... A couple pages that describe the differences linked below...
tl;dr if you are starting a solar battery project, LiFePo4 is the clear choice by far, unless you're going for the absolute cheapest possible build due to immediate budget constraints.
I've addressed LiFePo4 in my blog and why I'm not yet running this.
I'm trying to respond to some comments, but since this is not my thread, I'm rate-limited.
> Let's talk about the battery. I've chosen to use a large used lead-acid battery even though Lithium (LiFePO4) batteries beat lead-acid in every metric. I bought the battery second-hand for €100 so that's not a significant investment for a battery. Although it's a bit worn-down and the capacity is reduced, it is still good enough for me to run my computer setup for 10 hours after a full charge. The lead-acid battery also serves another purpose: is a relatively cheap option for me to validate my setup. If it works as intended, I might opt to upgrade to lithium (LiFePO4) at some point."
By far… not so. Just, marginally, as of the last year, perhaps - but the total cost over the lifetime per Wh of storage is still on a par with lead, because lead acid batteries are cheap as chips, require little or no maintenance if you’re sealed, and if you get something like OPzS cells and treat them well, you will get 20 years of life from them. LiFePo4, you’re looking at a decade, maximum, before they’re trash.
I set us up here, totally off grid, three years ago, using a bank of OPzS cells, giving us 42kWh of usable storage. I rarely take them below 70%. Their performance has barely budged since installation, and with the condenser caps, they have required zero maintenance - I check the specific gravity of the acid once a year, and go “yup”, and that’s it.
LiFePo4 I am considering for a booster bank at our cabin, which is 500m from our power shed, as the cable limits us to ~2.5kW here before we see significant voltage drop - it’s either that or step-up/step-down at either end, but transformers are surprisingly expensive. Main reason I’m leaning towards them for this application is mass, as our only access is either by foot or an aerial cableway - our lead bank weighs about 2000kg, equivalent LiFePo4 is about 450kg.
So - LiFePo4 is a decent choice, but depending on your application, a pile of big lead acid cells can be better. See, for instance, storage at various solar projects - it’s virtually all OPzS cells, as the amortised cost is still favourable.
I don't disagree with you but lifepo4 have a high upfront one time purchase cost for something equivalent in capacity to a 12V 100Ah AGM, like easily $450-500 per unit or more. They do pay for themselves over time with their much greater longevity.
Might be more than the blog owner wants to spend for what is just a fun hobby project.
There are some 3U rackmount size nominal 48vdc 50Ah lifepo4 (approx 4.8kWh capacity) with built in bms and LVD you can get from china now.
I'm going to disagree with you, because decent deep-cycle lead-acid batteries can last very well, and they are very much cheaper than LiFePO4. https://youtube.com/watch?v=LPPUqLZOqCQ is the video that persuaded me, even if he does ramble on a bit.
LiFePO4 age by elapsed time more than cycle count, so after 10 years they will be reaching the end of their useful life regardless of how much you have used them. Lead-acid age by cycle count more than elapsed time, so you could have a battery last well longer than 10 years if you treat it well.
I'd note that lead-acid batteries are divided into deep-cycle batteries that have are designed for longevity and basic batteries that are optimised for peak supply current (for vehicle starter motors). Use a deep-cycle battery, otherwise yes it will die very quickly.
I'd argue that if you're in a part of the world that has unreliable sunlight, such that you want to store say 4 days of energy but rarely actually use it all, then lead-acid is a perfect fit, because you just buy lots of storage at a cheaper price than LiFePO4, and that regime automatically treats the batteries well.
If you're in a part of the world where sunlight is reliably every day and you only want to buy enough battery to last a single night, then I can see that LiFePO4 may be a better option. But I'd still be inclined to buy several days of lead-acid instead. If you want to charge your batteries from cheap early morning grid power and effectively cycle twice a day, then LiFePO4 is definitely the better option.
The other thing that is nice about lead-acid batteries is the recycling rate - they are very easily recyclable and very highly recycled. I don't think we're there with LiFePO4 yet.
> unless you're going for the absolute cheapest possible build due to immediate budget constraints.
Or, you know, you get limitless amounts of 24Ah 12V SLABs free for the hauling away because they test at a bawhair under factory spec after five years of having an easy life.
> Although that sounds like a very light load, if you run it for 24 hours, it's equivalent to using 84 Watts continuously for one hour.
Its called 84 watt-hours and this is energy consumed in 24 hrs. 3.5 watts is energy consumption rate and is called as power(joules/sec). 84 Wh is not actually lot.
I made a calculator for raspberry pi energy consumption
But 84Wh is still enough energy to drive a modern battery-electric vehicle around 500 meters. Kind of puts things into perspective.
I find these numbers really fascinating because it shows how efficient battery-electric vehicles are, especially when you think about things like incandescent bulbs, which easily will run at 50W just to light up a small room.
Don't get me started on cars that display usage in kWh/h per 100km. Yes, you read that right.
For a comparison, 50W doesn't seem like much, right? Maybe if you're older you had 50W incandescent light bulbs in your house. Normal thing.
Let's say a WISP wanted to run a very basic off grid relay site with some radios that are 8-12W DC load each and a router that's 15W. Total around 50W 24x7x365. ((50 x 24 x 31)) / 1000
That's 37.2 kWh per month.
You need a surprisingly large amount of solar panels to generate a reliable 45-50 kwH per month to refill a battery bank every day when the sun comes up, in November, December, January, February at latitude 45N or above. Like, really, a lot more than you might think. Four or more 370W 72-cell.
Agree it doesn't feel like a lot. We run our house, including a decent sized pool pump, off solar for most of the day. A Pi seems like very small fry in the scheme of things.
Getting something like this up and running in a few short hours of Dutch summer sun just shows that everyone should be trying it (that includes me).
I am less of a DIYer than the author and safety was always a priority... good author knows about amps, cable sizes, etc.
But charging lead acid battery inside a house? I've stumbled across warnings where it says they must be charged in a well ventilated area. Anyone care to chime in, for the safety of author? https://www.ccohs.ca/oshanswers/safety_haz/battery-charging.....
Sealed lead acid (SLA) batteries only outgas an appreciable amount when overcharged/overdischared. Vented instead of sealed types can also be used indoors but require their own ventilation system. The majority of UPS systems use SLA batteries indoors.
For those thinking about replicating this: Victron is really popular because it's extendable and the management interface is reasonably open, but the zoo of required devices makes the costs explode quickly.
Maybe look at Deye instead. I'm running a 12kW unit (they're available smaller) with a 48V battery. The software is in poorly translated to English, firmware updates are made by the manufacturer remote on request and it has no shadow management (meaning it might end up on a local maximum in the MPPT, not the global maximum) - but the unit cost me about 3000€ with 10yr warranty instead of the >7000€ for an equivalent zoo of Victron parts.
Of course it can do black starts from PV or battery, and act as a UPS on a secondary output. Pulling data locally can be done using a RS485 modbus interface; so I open my firewall only for firmware updates.
The 3.6kW single phase unit (SG05LP1) can be had for less than 1300€. A 5kW three phase unit is only a little bit more expensive, but I'd worry about standby consumption in low power scenarios with only a few modules (mine hogs 80W, but a three phase Victron setup does so as well). These are string inverters, so you need more modules for them to reach their start up voltage, and then some more to put them into the MPPT zone. The 1 phase starts at 125V and the MPPT tracker works with 150-425V, the 3 phase units 160V & 200-650V respectively. When I browsed the market there were other offerings from other brands with 90V start up; but be careful to get a unit that's legal to connect to the grid IF you want to have grid fall back (here in Germany, Victron and Deye are legal - at least the parts I looked at. But you will always need a electrician with a concession to register them with the grid company. Some people don't care and just setup their systems though).
Important: The voltages depend on the chosen PV module; mine are in the 40V per module ballpark, but iirc I might maybe have seen up to 60V? So for the 3.6kW unit you'd want at least 3 or 4 modules.
Victron is good stuff and it is made to last. They're a big supplier to maritime integrators to provide power on board of ships of all shapes & sizes. I've yet to see a Victron inverter fail before the end of the lifetime of the installation it was a part of whereas most other inverters including Xantrex and ABB tend to die after a decade or so. Which isn't bad but still it can be a big hassle to replace an inverter if the form factor has changed.
Also: consider decoupling your battery charger setup from the solar portion, this will give you a lot more flexibility in terms of siting (you can then place your battery and charger where you want on your local installation). You can use HA to bring your battery online when it is most needed and even when to charge it based on the outputs of multiple fields of solar, an integrated solution really only works with a single inverter or a set of inverters of a single brand.
And if you can stay away from stuff that requires an internet connection to some manufacturer, not all upgrades are positives and your data shouldn't be going there anywhere. Also it probably isn't a good idea to hand over control of a grid connected device to another party, especially when that device has firmware that can't be audited.
Not sure what zoo of parts you’re referring to? I have two multiplus 5kva 48v, a bmv-712, a venus gx, and a pair of their biggest MPPTs - and for our pretty large install it shook out at about €4,500. Without the redundancy, it would have been more like €2,500.
Cool project. I think we really need some free software sensor/controller libraries/frameworks for solar setups.
The reason is that here in Germany, and presumably elsewhere in Europe, these "balcony powerplants" are taking off. You are allowed to plug up to 600W (soon up to 800W) into your socket without further trouble.
But unfortunately, most people will waste a lot of energy this way. Very few people will have permanent usage of 100W or more. Instead, consumers like refrigerators will turn on and off multiple times per hour.
So the ideal setup would consist of one or more load-measuring sensors, a smallish long-lasting battery (LiFe?), some oversized panels (say up to 2kW) and a converter that hooks everything up.
The controller should ensure that you feed power into your grid only when you need it and otherwise charge your battery. I think that such a setup could easily get you 4kWh/day of consumption in spring and summer. And potentially still 1kWh during most winter days.
Not sure if you saw but there's a great little German startup called "We Do Solar" who produce solar panels specifically for use on Balconies. My house has a flat roof and we'll be putting solar up there in the near future but I also plan to get panels for the balcony on our second floor as it runs the full width of the house and should add quite a chunk of generation capacity (downside is it's west facing so will only really provide power from the afternoon until the sun goes down).
Are there actually inert (non-flammable) batteries that have a decent energy density for this? I would be worried about having any kind of sizeable lithium battery in an apartment, considering even laptop-sized batteries have enough firepower in them (but at least that one can more or less be picked up and thrown out the window in an emergency).
The other problem is the 3.5 watt draw, or 600ma at idle, of the PI4B.
If you used a PI Zero with an ethernet expansion board this goes down to 100ma at idle. 6x less. You still get 1ghz cpu and 512mb of ram. I could even run django and postgres on that.
Certainly you don't need gigabytes of ram to run the blog. :)
The Raspberry 2 (original ARMv7 not underclocked Raspberry 3 ARMv8) is the best low power server. 1W idle and 2W 100% (6x more perf. than Raspberry 1 = Zero with Eth.).
They saturate the SD card SPI almost to the byte/second.
32-bit is enough forever, specially when you only have 1GB, but I'm staying on 32-bit on my 8GB RPi 4 too, because 4GB per process is enough when you also need the OS to have ample RAM.
If you are lucky enough to have some ARMv7 RPi 2 and/or Rpi 4 8GB, they will be priceless for eternity.
Did you ever work out how much energy was expended to manufacture and transport the parts? Chances are that with solar panels facing west in a place like The Netherlands, it will take a long time to come out on top with your carbon footprint.
I reckon that the most energy-efficient setup for your blog would be a hosted solution. Data centres are already optimised for low energy use. And some cloud providers have committed to become carbon neutral.
Lowering your overall household electricity use would be a more effective way to lower your carbon output.
> It's fair to say that my experiment isn't rational because of the sub-optimal solar conditions. Yet, I'm unreasonably obsessed by solar power and I wanted to make it work, even if it didn't make sense from an economic or environmental perspective2.
And I bet his hardware saturation is low too, making it an even worse use of resources compared to shared hosting in a data center that uses bin packing or live migrating VMs or whatever. Because in the end you care about resources used for the actual work done, not the work capacity of the hardware.
While it doesn't make much difference at this scale and it is a valid experiment to learn about solar power, it is telling of the general view about energy and environmental impact. People equate solar or wind or electric vehicles with green when the devil is always in the details.
> If you ever intend to build some kind of solar setup yourself, consider a 24 Volt or ideally an 48 Volt system to reduce currents and thus save on cabling cost.
I sort of regret going with a 48V system because it prevents me from plugging in a lot of devices directly to the battery. I have a few USB-C PD fast charging modules I would want to use directly. Also a battery-to-battery charger such as an iCharger or ISDT product won't do 48V as input or output. Not a big deal if you just want to connect an inverter all the time.
A more relevant issue may be that your solar panel's voltage will have to be > 48V. Actual voltage will depend on your MPPT charger. Victron seems to require battery voltage + 5V. Mine requires a minimal of 60V from the panels, so I have 3 24V panels wired in series, and cannot downsize.
I think 24V would've been a good sweet spot. The USB-C PD modules only step-down, so they cannot output 19V with 12V power.
Sorry for hijacking the topic. I also live in the Netherlands and my backyard perfecty faces south, which means i get huge sunlight on that side of the house. But because my house has a glass-roofed extension on the ground floor, all solar companies i spoke say they can’t install panels on the roof because they can’t build scaffold on that side.
Here’s an image to explain a bit better. [image](https://imgur.com/a/WE1Qojf)
So the red area is the glass-roofed extension on the ground floor. And blue area is the space on the roof that solar panels should be placed. Green is a dormer (which they said they can’t also put panels on top)
I was wondering any dutchies might know a solution/advice a company about this? Also is there any portable panels that i can put on top of the glass extension?
Hi, fellow Dutchie here. I've just built something quite similar and I took a bit of a shortcut: I've used the panels as the roofing. This was a bit tricky to do properly but now that it's done it looks gorgeous and works quite well. Drop me an email if you want pictures or if you want to come look at the setup in person. It's 18 panels, 3 'long' and 6 'wide' for a total of a bit over 32 square meters.
It isn't clear from the picture and I guess it's too obvious, but if you have a neighbour, they can climb from their roof. That's how my neighbour got his installation done.
I have seen them do more complicated installations (4 floors scaffolding + crane to lift panels), I don't know why they refuse that one.
I replied about this on another comment but have a look at "We Do Solar" their product is designed for installing on balconies but I guess there is nothing to stop you installing it where ever you like! (You might just need to add a bit of a frame to support them?)
not in NL but my parents have the same problem - glass roofed extension stops the installation
I dont understand why they can't just access the roof from the other side, climb over the apex and down. They walk all around on the roof once they're up there, does it really matter which side they climb?
It seems that a major cost of solar installations is the inverter. Power electronics that generate >100W AC power are big and expensive.
Now that more and more devices use USB-C PD for power, I wonder whether it would be possible to forego the AC inverter, and just power everything with small USB-C power supplies that have 12V input and can be powered directly from the battery.
Or maybe you could use a 110V inverter instead of a 230V inverter? Switched mode power supplies usually accept either.
> my balcony is facing east. This means it only receives direct sunlight from 16:00 onward during spring and summer.
I’m confused. The sun rises in the east. By late afternoon it would not be directly shining on an east-facing balcony, would it? The most sun would be in the morning on that east side, I would think.
It’s always frustrating to me to see an inverter in these setups. All of your digital devices actually run on DC current! Your computer, monitor, phone charger…
Inverters consume energy just being on, whether current is being drawn or not. And they’re expensive!
Without the inverter, a solar panel+battery setup is super simple and I’m curious to see a movement towards low-voltage circuits in homes.
You can easily power all of the lights in your home with a solar panel connected to a 12v battery. Double in size and you can power your TV and router as well.
This isn’t going to save you a significant amount of money though. It’s just interesting. Big ticket items like your water heater or air conditioner consume a lot more power and will probably need an inverter, etc.
The author already powers the Pi directly from the battery, and they switch off the inverter when it's not used. (see the image diagram and one of their responses in the comments)
Anyway, you wouldn't need a 'load' port in the charge controller, just put it in parallel with the battery.
Why do you think the Pi is powered via the inverter? I can't see mention of this, and the picture of their setup shows the Pi being powered by a step-down from 12 V.
I run a similar toy system with a 180w panel and it makes about 110wh a day on an average from march to October - due to a similar bad position the monitoring plug would use more power than the panel makes the rest of the year :P
It runs an inverter and offsets my electricity use.
I plan adding a battery this year but my MPPT charger has been stuck in Hannover for 3 weeks now - I suspect a customs issue.
I see a safety hazard with the exposed battery terminals (as shown in the picture "A 12 Volt 230 Ah lead-acid battery"). AFAIK, lead-acid batteries are less powerful than Li-ion/LFP but would probably still start a fire or give nasty sparks if something metallic falls onto the battery. (I'd be happy to be corrected.)
> The drawback of a 12-volt system is the relatively large currents required to charge the battery and power the inverter. This requires thicker, more expensive cabling to prevent energy losses in the cabling.
Arguably it's only for the discharging via the inverter that you need the thick cables, as otherwise they don't need to be thicker than the cables from the panels. (The current for charging could be much lower than the maximum discharge current.) -- Except if the MPPT steps down the voltage from the panels to the battery by a lot.
You don't need an inverter if you're just using an rpi. You can get away with a cheap 12v car USB adapter. I do this for my off-grid wifi (rpi and 5g phone plugged into USB).
If you only serve static files you can use Arduino (or better) MCU (it has lan shield) and decrease power consumption three times, and 18650 instead of car battery can perform better.
Being in the Netherlands makes this very challenging indeed. I am from the Netherlands but don't live there anymore. I came to visit family in December a couple of years ago instead of the usual summer trip and I had forgotten how incredibly gloomy it gets. Short days, dark, low hanging clouds much of the time. Not much solar energy on those days.
[+] [-] amatecha|2 years ago|reply
tl;dr if you are starting a solar battery project, LiFePo4 is the clear choice by far, unless you're going for the absolute cheapest possible build due to immediate budget constraints.
https://www.canbat.com/a-detailed-comparison-of-lead-acid-ba...
https://www.power-sonic.com/blog/lithium-vs-lead-acid-batter...
[+] [-] louwrentius|2 years ago|reply
I'm trying to respond to some comments, but since this is not my thread, I'm rate-limited.
> Let's talk about the battery. I've chosen to use a large used lead-acid battery even though Lithium (LiFePO4) batteries beat lead-acid in every metric. I bought the battery second-hand for €100 so that's not a significant investment for a battery. Although it's a bit worn-down and the capacity is reduced, it is still good enough for me to run my computer setup for 10 hours after a full charge. The lead-acid battery also serves another purpose: is a relatively cheap option for me to validate my setup. If it works as intended, I might opt to upgrade to lithium (LiFePO4) at some point."
[+] [-] madaxe_again|2 years ago|reply
I set us up here, totally off grid, three years ago, using a bank of OPzS cells, giving us 42kWh of usable storage. I rarely take them below 70%. Their performance has barely budged since installation, and with the condenser caps, they have required zero maintenance - I check the specific gravity of the acid once a year, and go “yup”, and that’s it.
LiFePo4 I am considering for a booster bank at our cabin, which is 500m from our power shed, as the cable limits us to ~2.5kW here before we see significant voltage drop - it’s either that or step-up/step-down at either end, but transformers are surprisingly expensive. Main reason I’m leaning towards them for this application is mass, as our only access is either by foot or an aerial cableway - our lead bank weighs about 2000kg, equivalent LiFePo4 is about 450kg.
So - LiFePo4 is a decent choice, but depending on your application, a pile of big lead acid cells can be better. See, for instance, storage at various solar projects - it’s virtually all OPzS cells, as the amortised cost is still favourable.
[+] [-] walrus01|2 years ago|reply
Might be more than the blog owner wants to spend for what is just a fun hobby project.
There are some 3U rackmount size nominal 48vdc 50Ah lifepo4 (approx 4.8kWh capacity) with built in bms and LVD you can get from china now.
[+] [-] mnw21cam|2 years ago|reply
LiFePO4 age by elapsed time more than cycle count, so after 10 years they will be reaching the end of their useful life regardless of how much you have used them. Lead-acid age by cycle count more than elapsed time, so you could have a battery last well longer than 10 years if you treat it well.
I'd note that lead-acid batteries are divided into deep-cycle batteries that have are designed for longevity and basic batteries that are optimised for peak supply current (for vehicle starter motors). Use a deep-cycle battery, otherwise yes it will die very quickly.
I'd argue that if you're in a part of the world that has unreliable sunlight, such that you want to store say 4 days of energy but rarely actually use it all, then lead-acid is a perfect fit, because you just buy lots of storage at a cheaper price than LiFePO4, and that regime automatically treats the batteries well.
If you're in a part of the world where sunlight is reliably every day and you only want to buy enough battery to last a single night, then I can see that LiFePO4 may be a better option. But I'd still be inclined to buy several days of lead-acid instead. If you want to charge your batteries from cheap early morning grid power and effectively cycle twice a day, then LiFePO4 is definitely the better option.
The other thing that is nice about lead-acid batteries is the recycling rate - they are very easily recyclable and very highly recycled. I don't think we're there with LiFePO4 yet.
[+] [-] roeles|2 years ago|reply
I'm asking because I'm creating a similar setup to OP to control the climate in my glider's trailer.
[+] [-] beachy|2 years ago|reply
[+] [-] Gordonjcp|2 years ago|reply
Or, you know, you get limitless amounts of 24Ah 12V SLABs free for the hauling away because they test at a bawhair under factory spec after five years of having an easy life.
[+] [-] op00to|2 years ago|reply
[+] [-] quaintdev|2 years ago|reply
Its called 84 watt-hours and this is energy consumed in 24 hrs. 3.5 watts is energy consumption rate and is called as power(joules/sec). 84 Wh is not actually lot.
I made a calculator for raspberry pi energy consumption
https://tinyurl.com/nwu6sn4s
[+] [-] vegardx|2 years ago|reply
I find these numbers really fascinating because it shows how efficient battery-electric vehicles are, especially when you think about things like incandescent bulbs, which easily will run at 50W just to light up a small room.
Don't get me started on cars that display usage in kWh/h per 100km. Yes, you read that right.
[+] [-] walrus01|2 years ago|reply
Let's say a WISP wanted to run a very basic off grid relay site with some radios that are 8-12W DC load each and a router that's 15W. Total around 50W 24x7x365. ((50 x 24 x 31)) / 1000
That's 37.2 kWh per month.
You need a surprisingly large amount of solar panels to generate a reliable 45-50 kwH per month to refill a battery bank every day when the sun comes up, in November, December, January, February at latitude 45N or above. Like, really, a lot more than you might think. Four or more 370W 72-cell.
[+] [-] somishere|2 years ago|reply
Getting something like this up and running in a few short hours of Dutch summer sun just shows that everyone should be trying it (that includes me).
[+] [-] jve|2 years ago|reply
But charging lead acid battery inside a house? I've stumbled across warnings where it says they must be charged in a well ventilated area. Anyone care to chime in, for the safety of author? https://www.ccohs.ca/oshanswers/safety_haz/battery-charging.....
[+] [-] drzaiusx11|2 years ago|reply
[+] [-] unknown|2 years ago|reply
[deleted]
[+] [-] archi42|2 years ago|reply
Maybe look at Deye instead. I'm running a 12kW unit (they're available smaller) with a 48V battery. The software is in poorly translated to English, firmware updates are made by the manufacturer remote on request and it has no shadow management (meaning it might end up on a local maximum in the MPPT, not the global maximum) - but the unit cost me about 3000€ with 10yr warranty instead of the >7000€ for an equivalent zoo of Victron parts.
Of course it can do black starts from PV or battery, and act as a UPS on a secondary output. Pulling data locally can be done using a RS485 modbus interface; so I open my firewall only for firmware updates.
The 3.6kW single phase unit (SG05LP1) can be had for less than 1300€. A 5kW three phase unit is only a little bit more expensive, but I'd worry about standby consumption in low power scenarios with only a few modules (mine hogs 80W, but a three phase Victron setup does so as well). These are string inverters, so you need more modules for them to reach their start up voltage, and then some more to put them into the MPPT zone. The 1 phase starts at 125V and the MPPT tracker works with 150-425V, the 3 phase units 160V & 200-650V respectively. When I browsed the market there were other offerings from other brands with 90V start up; but be careful to get a unit that's legal to connect to the grid IF you want to have grid fall back (here in Germany, Victron and Deye are legal - at least the parts I looked at. But you will always need a electrician with a concession to register them with the grid company. Some people don't care and just setup their systems though).
Important: The voltages depend on the chosen PV module; mine are in the 40V per module ballpark, but iirc I might maybe have seen up to 60V? So for the 3.6kW unit you'd want at least 3 or 4 modules.
[+] [-] jacquesm|2 years ago|reply
Also: consider decoupling your battery charger setup from the solar portion, this will give you a lot more flexibility in terms of siting (you can then place your battery and charger where you want on your local installation). You can use HA to bring your battery online when it is most needed and even when to charge it based on the outputs of multiple fields of solar, an integrated solution really only works with a single inverter or a set of inverters of a single brand.
And if you can stay away from stuff that requires an internet connection to some manufacturer, not all upgrades are positives and your data shouldn't be going there anywhere. Also it probably isn't a good idea to hand over control of a grid connected device to another party, especially when that device has firmware that can't be audited.
[+] [-] madaxe_again|2 years ago|reply
[+] [-] choeger|2 years ago|reply
The reason is that here in Germany, and presumably elsewhere in Europe, these "balcony powerplants" are taking off. You are allowed to plug up to 600W (soon up to 800W) into your socket without further trouble.
But unfortunately, most people will waste a lot of energy this way. Very few people will have permanent usage of 100W or more. Instead, consumers like refrigerators will turn on and off multiple times per hour.
So the ideal setup would consist of one or more load-measuring sensors, a smallish long-lasting battery (LiFe?), some oversized panels (say up to 2kW) and a converter that hooks everything up.
The controller should ensure that you feed power into your grid only when you need it and otherwise charge your battery. I think that such a setup could easily get you 4kWh/day of consumption in spring and summer. And potentially still 1kWh during most winter days.
[+] [-] hellweaver666|2 years ago|reply
[+] [-] tcfhgj|2 years ago|reply
[+] [-] Nextgrid|2 years ago|reply
[+] [-] winrid|2 years ago|reply
If you used a PI Zero with an ethernet expansion board this goes down to 100ma at idle. 6x less. You still get 1ghz cpu and 512mb of ram. I could even run django and postgres on that.
Certainly you don't need gigabytes of ram to run the blog. :)
[+] [-] bullen|2 years ago|reply
They saturate the SD card SPI almost to the byte/second.
32-bit is enough forever, specially when you only have 1GB, but I'm staying on 32-bit on my 8GB RPi 4 too, because 4GB per process is enough when you also need the OS to have ample RAM.
If you are lucky enough to have some ARMv7 RPi 2 and/or Rpi 4 8GB, they will be priceless for eternity.
[+] [-] goodpoint|2 years ago|reply
[+] [-] hankman86|2 years ago|reply
I reckon that the most energy-efficient setup for your blog would be a hosted solution. Data centres are already optimised for low energy use. And some cloud providers have committed to become carbon neutral.
Lowering your overall household electricity use would be a more effective way to lower your carbon output.
[+] [-] bartislartfast|2 years ago|reply
> It's fair to say that my experiment isn't rational because of the sub-optimal solar conditions. Yet, I'm unreasonably obsessed by solar power and I wanted to make it work, even if it didn't make sense from an economic or environmental perspective2.
This is just a fun experiment
[+] [-] trabant00|2 years ago|reply
While it doesn't make much difference at this scale and it is a valid experiment to learn about solar power, it is telling of the general view about energy and environmental impact. People equate solar or wind or electric vehicles with green when the devil is always in the details.
[+] [-] mgraupner|2 years ago|reply
[+] [-] ThatPlayer|2 years ago|reply
I sort of regret going with a 48V system because it prevents me from plugging in a lot of devices directly to the battery. I have a few USB-C PD fast charging modules I would want to use directly. Also a battery-to-battery charger such as an iCharger or ISDT product won't do 48V as input or output. Not a big deal if you just want to connect an inverter all the time.
A more relevant issue may be that your solar panel's voltage will have to be > 48V. Actual voltage will depend on your MPPT charger. Victron seems to require battery voltage + 5V. Mine requires a minimal of 60V from the panels, so I have 3 24V panels wired in series, and cannot downsize.
I think 24V would've been a good sweet spot. The USB-C PD modules only step-down, so they cannot output 19V with 12V power.
[+] [-] ofisboy|2 years ago|reply
Sorry for hijacking the topic. I also live in the Netherlands and my backyard perfecty faces south, which means i get huge sunlight on that side of the house. But because my house has a glass-roofed extension on the ground floor, all solar companies i spoke say they can’t install panels on the roof because they can’t build scaffold on that side.
Here’s an image to explain a bit better. [image](https://imgur.com/a/WE1Qojf) So the red area is the glass-roofed extension on the ground floor. And blue area is the space on the roof that solar panels should be placed. Green is a dormer (which they said they can’t also put panels on top)
I was wondering any dutchies might know a solution/advice a company about this? Also is there any portable panels that i can put on top of the glass extension?
Thanks
[+] [-] jacquesm|2 years ago|reply
[+] [-] kippel|2 years ago|reply
I have seen them do more complicated installations (4 floors scaffolding + crane to lift panels), I don't know why they refuse that one.
[+] [-] hellweaver666|2 years ago|reply
[+] [-] bartislartfast|2 years ago|reply
I dont understand why they can't just access the roof from the other side, climb over the apex and down. They walk all around on the roof once they're up there, does it really matter which side they climb?
[+] [-] newaccount74|2 years ago|reply
Now that more and more devices use USB-C PD for power, I wonder whether it would be possible to forego the AC inverter, and just power everything with small USB-C power supplies that have 12V input and can be powered directly from the battery.
Or maybe you could use a 110V inverter instead of a 230V inverter? Switched mode power supplies usually accept either.
[+] [-] jb1991|2 years ago|reply
I’m confused. The sun rises in the east. By late afternoon it would not be directly shining on an east-facing balcony, would it? The most sun would be in the morning on that east side, I would think.
[+] [-] ccorcos|2 years ago|reply
Inverters consume energy just being on, whether current is being drawn or not. And they’re expensive!
Without the inverter, a solar panel+battery setup is super simple and I’m curious to see a movement towards low-voltage circuits in homes.
You can easily power all of the lights in your home with a solar panel connected to a 12v battery. Double in size and you can power your TV and router as well.
This isn’t going to save you a significant amount of money though. It’s just interesting. Big ticket items like your water heater or air conditioner consume a lot more power and will probably need an inverter, etc.
[+] [-] cr3ative|2 years ago|reply
The SmartSolar can provide output the Pi can use. Why not just throw a 12v-compatible USB power supply on there?
Going up to mains then back down to 5v seems inefficient. Am I missing something?
edit: I'm wrong! My SmartSolar has "LOAD" output but OP's does not. Ref: https://www.victronenergy.com/solar-charge-controllers/smart...
[+] [-] roeles|2 years ago|reply
https://www.uugear.com/product/zero2go-omini-wide-input-rang...
[+] [-] asolidtime1|2 years ago|reply
[+] [-] pflanze|2 years ago|reply
[+] [-] blkhawk|2 years ago|reply
It runs an inverter and offsets my electricity use.
I plan adding a battery this year but my MPPT charger has been stuck in Hannover for 3 weeks now - I suspect a customs issue.
[+] [-] pflanze|2 years ago|reply
> The drawback of a 12-volt system is the relatively large currents required to charge the battery and power the inverter. This requires thicker, more expensive cabling to prevent energy losses in the cabling.
Arguably it's only for the discharging via the inverter that you need the thick cables, as otherwise they don't need to be thicker than the cables from the panels. (The current for charging could be much lower than the maximum discharge current.) -- Except if the MPPT steps down the voltage from the panels to the battery by a lot.
[+] [-] turtlebits|2 years ago|reply
[+] [-] mugiseyebrows|2 years ago|reply
[+] [-] wkjagt|2 years ago|reply
[+] [-] bar000n|2 years ago|reply
[+] [-] unknown|2 years ago|reply
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