diy solar

diy solar

Looking for some advice on my first 730Watt Off Grid

coalfield

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Sep 12, 2021
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Looking for a basic solar off grid setup, for a DIY project in the UK

I have very limited space (2x2.4m) tiles roof (south facing) where I am planning to install.

I am building my kit list and would welcome any feedback on what I plan to buy and any better options that may be out there.

My calculations show I should be OK for the panels with the all in on, and the battery would allow output of 800Watt output from the inverter for ~3 hours). I would probably use more like 200W.

No idea if those panels are any good I just like the look of them and the specs.
Also the battery is just a cheap one, welcome any thoughts on other good value ones out there that I could consider?

Welcome any feedback if I have spec'd this suitably (and safely).
 
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Looks good! My only input is that the PV breaker should be 15A or 20A vs 63A. From the PV spec sheet, it looks like the max current is ~11A and the max series fuse is 20A.
 
Looks good! My only input is that the PV breaker should be 15A or 20A vs 63A. From the PV spec sheet, it looks like the max current is ~11A and the max series fuse is 20A.

Thanks your right the max current is 20A, the odd thing is the manual recommends 63A. Could this be because it needs some headroom for a spike? Or less risk of current actually getting too high from a PV? Or even that it can cope with a current up to 63A as it will clip it?

pv.JPG
 
Thanks your right the max current is 20A, the odd thing is the manual recommends 63A. Could this be because it needs some headroom for a spike? Or less risk of current actually getting too high from a PV? Or even that it can cope with a current up to 63A as it will clip it?

View attachment 64566

The inverter has a higher fuse amp spec because you could put your panels in parallel rather than series or have different panels. But the fuses or breakers should be sized the lowest rates equipment - the panels in this case.
 
The inverter has a higher fuse amp spec because you could put your panels in parallel rather than series or have different panels. But the fuses or breakers should be sized the lowest rates equipment - the panels in this case.

But in parallel I am still limited by the 20A input so I cant understand why it would recommend 63A, there is surely a reason? For every other fuse there is a specific rating.

Also the last model is a 48V version... with a lower 32A breaker recommendation, but am I right in saying the panels are not specifically 24V or 48V, that's what the CC is for... so why would the breaker change?! The last model if anything will have a higher limit on the input Amps from PV.
 
But in parallel I am still limited by the 20A input so I cant understand why it would recommend 63A, there is surely a reason? For every other fuse there is a specific rating.

Also the last model is a 48V version... with a lower 32A breaker recommendation, but am I right in saying the panels are not specifically 24V or 48V, that's what the CC is for... so why would the breaker change?! The last model if anything will have a higher limit on the input Amps from PV.

I cant really answer all your questions, just not familiar enough with this piece of equipment. But, I think the max PV charge current is 30A. There's a discrepancy between the overview and specifications on the aliexpress page so I looked up the technical specs, here: https://www.manualslib.com/manual/1335284/Epever-Up1500-M3222.html?page=26#manual
 
I cant really answer all your questions, just not familiar enough with this piece of equipment. But, I think the max PV charge current is 30A. There's a discrepancy between the overview and specifications on the aliexpress page so I looked up the technical specs, here: https://www.manualslib.com/manual/1335284/Epever-Up1500-M3222.html?page=26#manual
You are right its max 30A, but is max 30A across that range apart from the UP3000-M2142 so looks to recommend a breaker which is double the max PC charging current. I suspect it simply clips any additional charging current and hence the breaker recommendation.
 
Seen in the manual it also states it will simply clip higher current input to the max, providing its not in reverse polarity which helps explain the breaker

pvlimit.JPG
 
why is it I have mpp solar internal resistance but epever doesn’t get my spidey senses up?
 
Worth noting I just found out the EPEVER does not support lithium batteries :(
Found out from where?
and Why not?!
Mine has default lithium settings if I’m not mistaken. Pretty sure, actually. Either way you can configure it for whatever battery.
I’ve never wanted or needed to configure lifepo as I’m cheapo lead acid. And I configured for that.

Do you mean yours doesn’t? This is confusing.
 
Found out from where?
and Why not?!
Mine has default lithium settings if I’m not mistaken. Pretty sure, actually. Either way you can configure it for whatever battery.
I’ve never wanted or needed to configure lifepo as I’m cheapo lead acid. And I configured for that.

Do you mean yours doesn’t? This is confusing.
Apparently not, EPEVER support told me it does not support Lithium. I am guessing the way the charge controller charges the cells.
The question came about as there is no mention on Lithium in the manual:



lithium.JPG


@12VoltInstalls Which unit do you have?
 
@12VoltInstalls Which unit do you have?
Not relevant. A read a lot of threads. The unit you describe appears to be a hybrid?
I’ve gotta straight up SCC

No matter, though: if you can program the thing, you just set the equalize voltage to something less than or equal to your batteries’ recommended max charging voltage and set the boost and float appropriately as well. Then presto! you are compatible with lifepo, you just need to not exceed the max C-rate for the battery
 
The unit you describe appears to be a hybrid?

No matter, though: if you can program the thing, you just set the equalize voltage to something less than or equal to your batteries’ recommended max charging voltage and set the boost and float appropriately as well. Then presto! you are compatible with lifepo, you just need to not exceed the max C-rate for the battery

Yeah its a Hybrid.

Thanks for the advice its good to know I could use LifePO4 as its what i planned all along with the unit. What I dont understand is why they didnt simply add it as an option if its only the boost and floats values I need to worry about?
 
What I dont understand is why they didnt simply add it as an option if its only the boost and floats values I need to worry about?
I don’t know. Maybe because it works as is, and forces people to determine parameters from the battery manufacturers data rather than select some ‘generic’ default? LiFePo batteries are not all the same. Yes: lead acid aren’t all the same either but they have a margin of tolerance that lifepo does not
 
I don’t know. Maybe because it works as is, and forces people to determine parameters from the battery manufacturers data rather than select some ‘generic’ default? LiFePo batteries are not all the same. Yes: lead acid aren’t all the same either but they have a margin of tolerance that lifepo does not
I think your right. I am guessing that they dont trust a user to input the variables and it not to conflict with the BMS... but still odd they outright say it does not support it?

Does the way the Boost and Float charge change with respect to Lithium and Acid? Thats the only thing I could think of which may cause a problem.

While on the subject, I am not particularly happy with the Low Voltage Disconnect for the Epever, it defaults on AGM to 10.5V. Is this the same with your charger, or do you modify this? The Max I can goto is 11.6V by switching to manual settings (opposed to AGM)
 
am not particularly happy with the Low Voltage Disconnect for the Epever, it defaults on AGM to 10.5V. Is this the same with your charger, or do you modify this? The Max I can goto is 11.6V by switching to manual settings
I don’t recall? But you’re talking an inverter/controller, right? I just have an mppt charge controller and I believe that ‘disconnect’ setting is for the ‘load’ function- and I don’t use that at all.

If you have the inverter/controller aio and you worry about 11.6 for lifepo you have other issues to address. I configured my system hardware-wise so that I don’t ever see below 12.1- enough batteries enough solar. After 5 cloudy days I did hit 12.0 last week but that’s the first time in a couple years (and I have a 120VAC fridge) but I’m flooded lead acid

Either way- you have to either manage demand or add hardware if low voltage cutoff is a definite concern in practice. Low voltage disconnect is a last resort protection for an anomaly, shouldn’t be a plan. Imho
 
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