A close friend recently inquired me concerning a strange question. He started asking about aquarium water pumps and the thing ended up in that, apparently, someone is interested in the installation of an aquarium “in the middle of nowhere” (!), I mean, somewhere in the countryside but… without access to power lines.
Beyond my amazement, I've searched for whatever would be required to keep a 20W water pump running all day long without interruption.
According to my math, to cover ≈16 hours of a day at ≈23W, which is the 20W consumed by the pump plus DC/DC converter losses, 368Wh are required (total power consumption per day would be 552Wh). This means big battery, no less than 552Wh in case of a li-ion battery if the aim is to just use ≈70% of its capacity by charging at a lower maximum voltage, to ensure absolute maximum cycle life. I've also thought in using deep cycle lead acid batteries, but after looking at certain VMF DC18-12 datasheet I'm not impressed with their cycle life.
The climate here is pretty sunny all year round, this is good news but, in any case, there may be a cloudy day or two. To prevent having to install an insanely big battery, I think the smart option is to install maybe a couple 100W solar panels. In a sunny day both panels should at least average 60W/hour for no less than 8 hours, this is ≈960W raw input power. But I honestly do not know how much performance will the panels give in cloudy days. If the installed battery has, let's say, 560Wh useable capacity, certainly some power has to go in in a cloudy day if the aim is to withstand a following night (we've not taken into account charge controller losses, although they should be slim). Suffice to say I have 0 experience with solar panels, and this is the reason I am asking.
And of couse some cables and other thingamajigs like a buck controller for the pump.
Well I think this is more or less nailed as far as my knowledge goes, yet suffice to say it's going to cost a good deal of money once the battery pack and the installation is taken into account…
The panels can power the setup during the day the battery is for times when the panels dont produce power. So you need to have enough panels to charge the battery and power the setup.
I have a single 100W panel. For three days in a row now, it has produced <10Wh. Of course this if Finland, but I wouldn’t trust a solar panel for devices that absolutely need to be powered on 24/7 without a huge battery.
Pssst! Maukka see my signature (your image doesn't meets mobile friendly standards). :-D
Thanks, that was enlightening. Looks like the above panel only worked at a good pace for a single day out of 7, with another two honorable mentions.
Spoke a bit more with my colleague. Apparently the pump setup is to move water between adjacent ponds or bogs, and doesn't need to be powered 24/7. This is quite a difference.
The above graphic is pretty useful, lets me know the panels will only be able to power up the pump setup for a few hours a day, if anything, without a battery. I can now see the problem much better, namely because it is not coral, fish and squid life critical.
Get the Max Watts to Dollar you can find, S/H 250-300w grid tie panels are ideal giving 3 times the power of most 100w panels for the same price, what ever you think you need triple it
cheap PWM controllers can cut panel watts by up to 50%! (look up MPPT) its a tuned buck conversion far far more efficient
Lead acid is ok if you get GEL batteries , lion is better but massively more expensive.
On a good day my little hobby system produces around 1kw for 5-6 hours generating roughly 6Kw/h it stores 2.5Kw/h of that for night time and sends the surplus to the Grid tie… on a bad day it can make as little as 0.2kw/h for the entire day, during the winter i don’t even bother to cycle the batteries i just fully charge them and switch panels directly to a grid tie.
230AH 24v Gel Bank / only cycled to 50% dod giving 2000+ cycles.
Here’s what a winter week can look like!
Wind turbines can help, there are some quite reliable kits coming out of china that can hit around 400w TurbineVideo review
My colleague told me the “potential customers” aim to lay some fresh water fishes in the ponds (!), and they will see how much will it go without water circulation. The stuff will have maintenance every two days at least. I am no aquarium expert, so don't know how senseless or senseful this is.
Yes very nice setup The_Fat_Controller, that should allow you to save quite some money in electricity bills. Thanks for pinpointing the above concerning MPPT controllers (so much abbreviations which God knows :facepalm: what they mean without proper context).
The above panels are good, or so it looks to me (the bulk of this message was writen before hank's latest contribution). The question here is more like how many of them will be required, either two or three for the time being.
In the meantime I looked for some no-frills, affordable MPPT controllers:
The issue you will face with most of these is not conversion efficiency but very restricted charging options, many do not have voltage sensing and reliy on preset values with timers ok for floaded lead acid but not much else
Others such as the Epever tracer Tracer Series offer more control and can be setup for custom charging routines I believe these can be setup to safely and correctly charge lion cells they also support load shedding and remote access, the epever is a good controller and i used one for quite a while (there maybe better options available now)
The Victron controllers are probably the best they have full customisation of the charge routine and can be programmed for any type of cells such as Tubular Gel li on, lifepo4 etc , bulk absorption float etc and it is all monitored on battery voltage with full customisation
Victron is surely the way to go if you just want it to work and make configuring easy. It’s very handy to monitor locally or over the internet with a Raspberry Pi running Victron’s Venus OS.
Mine is just in the testing phase, since I don’t have a good location for the panels.
Bottom line with panels is Watts are watts and the more you can get per dollar spent the better , being more efficient simply means a smaller panel gives the same watts. but if it costs you 3 times as much per watt its pointless. Large industrial panels are built to last many years mine tested to 275w each (300w rated) and cost about 100 bucks each The ones you point out on alliexpress are not bad if they really give 200w for 120 bucks but id check the reviews on them not all panels are created equally and price doesnt always mean a lot
NOTE: you will almost never see the full rated output from panels unless they are below 25C. people always assume you get max power in really bright hot sun but this is not the case. as semiconductor temperature rise efficiency drops (solar companies neglect to mention this)
I love the victron Its very good controller but OWch! the Price sucks!!
PS: for good cheap inverter option PURE SINE , look into APC Smart UPS can be controlled vier Virtual load output on controller. (Epever also) I used this method initially but found grid tie inverter to be more suitable for my needs but if i was going offgrid I would go straight back to the APC
There is a guy on Youtube by the name AverageJoe , he has many detailed videos on making and protecting Lion packs as well as balancing & monitoring well worth a watch
I don't have any direct experience with this pump. The PV version of it can be connected directly to solar panels without separate controllers or batteries.
Sort of nailed it, :-) thanks. For just a tiny bit more money than the aforementioned Sunyima it offers better interface and looks like a better overall machine, even though it is fan cooled…
The panels are a bit more expensive , I see €142.16 for a pair and €209.49 for a 3-pack @ solarfactoryretail.
What the… wow! That pump is @#$% expensive!
Thanks to everyone, for now I have plenty of data to start with. This project will load the battery with buck or buck-boost converters and DC pumps but pretty sure I'll take a look at the inverter thing sooner or later. Many of the “high end” device suggestions will come into play once I am more familiarized with the stuff, I presume.
No worries , those little 7210a’s really are excellent for the price only issue is they are boost so battery bank needs to be higher voltage than panel but its ideal if you want to run a 24v bank with an 18v pannel
Wellp, while I am more or less fluent in read and written english language, the same I cannot say concerning spoken english understanding. I may have certain negative beliefs in this regard, forged at an early age.
Despite this, looks easy to understand. In red is the input voltage from the source (panels, wind turbines, mini-stellarator or mini-tokamak, etc.). In purple, with yellow V is the settable battery output voltage, and with yellow A the settable maximum output current. Below and all in yellow is output power in watts. In cyan colour figures battery capacity can be specified (what the point is right now I don't know), and a timer count whose point is also sort of pointless :-D to me. At the right side column I see a diskette icon with a two digit counter, I presume that is a writeable¹ array of memory presets…
I also have a small concerning doubt with the MPT-7210A, will it be able to support 16.6̅7 amps of input? I know I should stay below 10A at the output (for such I thing I would choose no less than a 9S li-ion battery for 200W of “18V” panels, and a minimum of 13S for 300W), but no figure I've found yet concerning input limit. The above Sunyima boost controller specifies 16.7A maximum input current, for example.
Generally the max current is regardless of voltage , as such most controllers will handle more watts at higher voltage
For example my victron is rated for 30amps , if i run a 12v battery bank my PV max will be 440Watts , but if i run in 24v @ 30 amps i can have upto 890w of PV and so on
the MPT-7210A is 10amps max input or output ,so you’d need to go 48v (13S) bank and run your solar panels in series to give 36v that way you never go above 10amp on the charge controller.
The issue then is getting from 48v back down to the voltage you need for the pump so you’ll need a converter
Well, for now I can say this thread gained a lot of momentum. It's been a busy O:) weekend.
Guess that arithmetic is maximum charge voltage times maximum current, yet these are maximums and you don't want to be pressing the pedal to the metal frequently, or do you? Long term reliability matters.
Well, I discern the MPT-7210A is then not really well suited to handle 2 × 100W “18V” panels in parallel, as they can give out in excess of 5.5A each.
Given this and considering I may go with up to 4 × 100W panels, the better affordable solution as I see it is to choose 2x (Sunyima) CTK-EV-300 charge controllers, each one fed by 2 × 100W panels.
Well… in reality it is very very rare that you will ever see the maximum from a solar panel unless as someone else said it is Freezing cold and you have very very strong sun , the ratings they give for Pmax assume absolute perfect conditions, Most sensible controllers are also current limited so they will simple draw up to their max rating rather than self destruct
[quote=Barkuti]
correct it would be 2 panels in Series… Parallel would be to much current also no head room for later upgrade , it is always better to get a larger controller if you can
There are some very nice Boost buck up & down converters around you dont need to spend alot of money to get the power out of the panels, the issue is as i said earlier going to be safely charging lithium batteries
Im not sure of the requirements for charging Lithium cells … for my Tubular Gel batteries they require a current limited 3 stage charge , Bulk Absorption & float and each voltage has to be temperature compensated (if you cause a gel battery to GAS) it is ruined and capacity lost so they must never be equalised
Im no expert on lithium but id imagine at the very least they will need Balancing, current limiting & over voltage protection , I think i also read somewhere they must not be charged if temperature below 0
I would have preferred lithium but cost was an issue and price difference big 80ah at 12v Lifepo4 , VS 110ah at 12v Tubular GEL …
The ones you point out on alliexpress are not bad if they really give 200w for 120 bucks but id check the reviews on them not all panels are created equally and price doesnt always mean a lot
