Solar Panels

[JLMAC]

Hi everyone,

I'm putting together a 48V system, using the EG4 48V LifePower 4 rack battery and the Growatt 3kW Stackable off-grid Inverter SPF 3000TL LVM-48P for a small RV. I need advice picking two 400w panels that would be compatible with the SPF 3000TL LVM-48P Inverter. I'm going with this inverter because it has a lower voltage solar panel demand (VoC?) than the EG4 3000kW Hybrid Inverter. I don't have much surface area to mount the panels; that is why I'm going with the two 400w panels. Can any of you please point me in the right direction with the solar panels and recommend a brand with the panel model? Thanks.

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[MichaelK]

I'm going with this inverter because it has a lower voltage solar panel demand (VoC?) than the EG4 3000kW Hybrid Inverter.

Could you please explain what you think this is an what you think it means? I suspect you are confused as to what the terminology means. A higher Voc limit is in general a positive factor.

 

[JLMAC]

Yes, my apologies. My original thought was to have the backbone for the system the EG4 48V LifePower 4 rack battery and the EG4 3kW Hybrid Inverter, with 800w worth of solar panels because I have limited mounting area for the panels (65”x72” or so). But the EG4 inverter needs a minimum solar panel voltage input of 120V just to turn on. I was not been able to find the panels with the right voltage and size to satisfy the minimum voltage of the EG4 Inverter and fit the panels in the mounting area I have. So, I scrapped that EG4 inverter and picked the Growatt 3000w hybrid inverter (SPF 3000TL LVM-48P), which has a significantly lower minimum solar panel voltage input requirement to charge the battery than the EG4, albeit it also has a lower maximum PV voltage input than the EG4. So, I’m essence I’m looking for panels that can supply 800w an can fit in my mounting surface area and work with the Growatt Inverter. I hope I added clarity to my situation. Thanks

 

[Supervstech]

Yes, my apologies. My original thought was to have the backbone for the system the EG4 48V LifePower 4 rack battery and the EG4 3kW Hybrid Inverter, with 800w worth of solar panels because I have limited mounting area for the panels (65”x72” or so). But the EG4 inverter needs a minimum solar panel voltage input of 120V just to turn on. I was not been able to find the panels with the right voltage and size to satisfy the minimum voltage of the EG4 Inverter and fit the panels in the mounting area I have. So, I scrapped that EG4 inverter and picked the Growatt 3000w hybrid inverter (SPF 3000TL LVM-48P), which has a significantly lower minimum solar panel voltage input requirement to charge the battery than the EG4, albeit it also has a lower maximum PV voltage input than the EG4. So, I’m essence I’m looking for panels that can supply 800w an can fit in my mounting surface area and work with the Growatt Inverter. I hope I added clarity to my situation. Thanks

So, how many panels do you think you have room for?
3?
My 240W used panels are about 42Vmp each,
My 375W panels are about 37V each...
I have seen 72V panels but they are far less popular.

 

[MichaelK]

Just skip the AiO route completely. With a component system you could design it around two 72-cell panels. But, you might want to rethink the 48V system voltage if your solar space is that limited. Less than 800W would be very small for a 48V system, for which I would consider 3000+W as being appropriate. Actually, I would consider 800W on the low side even for 24V, but doable.

You really haven't mentioned anything about the loads you would be powering, which should have been the starting point in your design phase. I'll give you my rough guidelines as to what I think is appropriate. Others here will contradict me.

0-1000W: 12V
1000-2000W: 24V
>2000W: 48V

I assume in an RV you won't be running things like a well-pump, so most likely 24V will work fine for you. Keep in mind though that if you have to mount your panels flat on the RV roof, that will decrease capacity even more. Don't expect more than 60-70% of rated output for flat-mounted panels.