Can I load an EcoFlow River Max portable power station with one or two PV panels in case of a missing grid (e.g. blackout several days)? So I just need a limited DC input and I think a solar charger without battery could do the job?
Panels: 2x 405 Wp max, Umpp 34.4 V, Impp 11.77 V (the voltage too high for the power station)
Power station load inputs:
- DC in: 10-24 V, 12 A, max. 200W!
- Car DC in: 12 V , 8A
- AC in: 230 V, max. 500W
Unless the charger is dumb the answer would be no, although there may be caveats...
I was going to ask why no battery but given that you are charging a battery and probably don't want to add another or bypass the charger in your power bank I guess I appreciate why you are asking.
A buck converter would likely be a better choice than a solar charger but you would still have to handle what happens when the PV isn't providing sufficient voltage to support the charging system as a whole. O and deal with open circuit voltage too.
Impp is Amps not volts and the open circuit voltage on those panels is going to be in the region of 40V (Just a guess based of typical values.)
Just looked at the site... seems expensive but pretty.
Why wouldn't you just use a 12V, nominal, panel?
That would have an open circuit voltage of around 21/22V with Vmpp at about 18V.
I suspect that is what the wide DC input is designed for, heck it may even have MPPT.
I think you may be overcomplicating things but as I remember doing that many times whilst I was learning stuff I decided to comment.
This isn't an answer to your question because I think your question is not the right one.
It looks to me like the unit supports solar charging natively and all you need to know is what panels will be compatible...
The site states 200W max solar, and then describes connecting 2X110Wm panels!
The DC In spec suggests, but doesn't state, that the charge is controlled, which would be logical, and is also limited to 12A. Given that at 10V 200W isn't possible at 12A it sounds like it will take what it needs whilst protecting itself from overcurrent (Just an assumption)
If the assumption is correct then any supply that isn't going to exceed 24V, even when the charge current is 0, should be fine, and that would be almost all 12V, nominal, panels. no matter the wattage you stack up.
You are probably better asking the manufacturer rather than us though.
Last thought...
A 40-50 Ah LiFePo4 12V battery with mains charger, solar charger and 600W inverter would probably work out at a similar price, if not less, and will have at least doubler the working life. Granted it wouldn't be as pretty.
Wow, what a precise response, Alistair, thank you very much!
To explain the background of the question:
The question is now how to bring these worlds together - if possible at all. In the second case I need an operation in an isolated network so the inverters I have are not usable at all.
"you may be overcomplicating things" -> what a good observation! :) A 12V battery would make it much easier. So I will evaluate these points as you proposed in your answer:
So thank you for your advice!
BTW: your're right - it's Impp 11.77 A and not Impp 11.77 V.
Well that makes more sense now and explains the panel mismatch and why you don't want to use a different panel/s.
A buck converter will drop the panel voltage to something the power pack can accept either on the DC input, designed for solar or on the 12V input. However if the panels are providing less than the dropout voltage of the buck converter odd things may happen and, depending on the buck module, you could end up with the system oscillating. That probably wouldn't be good.
If you buy a small solar charger, a good one, which I assume is why you are asking here, and a battery big enough to accept the output from the charge controller when it is maxed out yoiu should be able to couple that directly to you 12V input.
Assuming you buy a SmartSolar 75/10 or 75/15 then you would be well advised to get a 12V LiFePO4 packaged battery of 20Ah or 30Ah respectively. That way you max charge will be C/2 and the charge controller will clip, just not use, anything you collect above that charge rate.
The Smart Solaar can be configured to connect and disconnect the load at various voltages, protecting the battery, and in your case the power pack, from a low voltage condition.
Both units support 15A out to the load, will operate at 12 or 24V, support panel strings up to 75V OC and have MPPT optimisation built in. I believe , although you should check if you go this way, will limit charge current to the battery whilst supplying excess solar current to the load if it will take it.
BlueSolar and SmartSolar have almost identical specs/capabilities in this size range.
SmartSolar has a really nice Bluetooth interface and works with the Victron Connect App giving you real time and historical data, including battery capacity estimates.
BlueSolar collectts/provides the same data but only over a VE.Direct interface for use by a Victron system.
Confusingly, the one with Blue in the name does not support Bluetooth, unless you add a dongle.
FYI, The Bluetooth version, SmartSolar MPPT75/15, is about £100 in the UK right now.
Do you already have the Eco Flow? you could get a pretty big LiFePO4 battery for that money!
Victron Phoenix 500VA, 12V inverter ~ £130
55Ah Battery with charger ~ £240 - 105Ah Battery with charger ~ £450
(Ultramax as examples but there are others)
The batteries would not be up to Victron standards but I have been ruining on on my caravan for the last 2.5 years and another set up as a UPs for the last 3.5 years.
Glad to help, just wish I could answer my own questions :-)
Al
