Is my Solar panel too large for my system

[Jack D]

Hi Guys,

I have an EcoFlow Delta 2 power station that specifies its solar input as 11-60V, 15A and 500 Watt maximum.

I already have a 575 watt solar panel. It’s data sheet specifies:
Voc 52.32
Isc 13.89
Vmp 43.85
Imp 13.11
Pmax gain 0

When I have run the numbers it looks like even in cold conditions and perfect sunlight the V falls below 60V, but only just!

What I would like to know is whether my calculations are correct and this is safe for the power station. I’m trying to save myself re buying a smaller solar panel, but at the same time it’s not worth damaging the power station and potentially voiding its warranty. So ultimately should I bite the bullet and buy a 400 watt solar panel that falls comfortably within the power ranges and still gives the required charge comfortably.

Any advice and how you came to this conclusion would be greatly appreciated.

Jack

 

[Supervstech]

Should be just fine.
Ya might want to disconnect on very cold nights, but otherwise i dont see any issues.

Panels dont push watts, loads pull them, so the unit will only pull a max of 500W

 

[Jack D]

Should be just fine.
Ya might want to disconnect on very cold nights, but otherwise i dont see any issues.

Panels dont push watts, loads pull them, so the unit will only pull a max of 500W

Great thanks for the advice. So disconnect over night then hook back in once the temperature rises above 0 degrees?
I have two 15A in line fuses I was going to install on the MC4 to XT60 cable line, would that work as protection for cold weather high voltage and blow before damaging the power station inverter?

 

[SomethingAppropriate]

protection for cold weather high voltage

No. In fact. Those fuses won't do anything at all for you.

 

[mikefitz]

I already have a 575 watt solar panel. It’s data sheet specifies:
Voc 52.32

Typical voltage increase at low temperature is 0.3%/deg C below 25 deg C. You should be OK down to -25degC.
There is no damage going overvolts on the Delta 2, it just stops accepting power.

 

[Supervstech]

Typical voltage increase at low temperature is 0.3%/deg C below 25 deg C. You should be OK down to -25degC.
There is no damage going overvolts on the Delta 2, it just stops accepting power.

I wouldnt wanna take that risk.

 

[Jack D]

I wouldnt wanna take that risk.

So at what temperature would it be a risk to leave the panel plugged in?

 

[mikefitz]

temperature would it be a risk to leave the panel plugged in?

Below -25 deg C. It does not get that cold in New Zealand.

 

[Jack D]

Typical voltage increase at low temperature is 0.3%/deg C below 25 deg C. You should be OK down to -25degC.
There is no damage going overvolts on the Delta 2, it just stops accepting power.

So I spoke with an ecoflow technician today. He was very helpful. He said that the delta 2 could stop accepting additional amps but that it could not stop accepting volts and that would fry the system. He thought my panel on paper would be ok however because it is not within specified range of watts it would void my warranty. I think the warranty is worth more to me than the cost of a new panel so I will look to buy one. Cheers for all the advise.

 

[Jack D]

No. In fact. Those fuses won't do anything at all for you.

I thought this might be the case. Could you please explain why this is?

 

[zenniz]

I thought this might be the case. Could you please explain why this is?

Fuse protects your equipment from over current, won't protect from over voltage.

 

[Jack D]

Ah

Fuse protects your equipment from over current, won't protect from over voltage.

Ah ok so in the case of a solar panel watts increase with the sunlight and that causes an increased voltage but doesn’t necessarily mean the amps increase as well?

 

[herbyrainer]

Should be just fine.
Ya might want to disconnect on very cold nights, but otherwise i dont see any issues.

Panels dont push watts, loads pull them, so the unit will only pull a max of 500W

Hello, Could you clarify the statement about disconnecting at night, as I am confused about how any volts would be drawn when it is dark?
Many thanks.

 

[crossy]

Hello, Could you clarify the statement about disconnecting at night, as I am confused about how any volts would be drawn when it is dark?
Many thanks.

The danger time is just as it gets light after a cold night.

The panels come up to voltage much more quickly than people expect although there's little actual power available. It's this voltage that could possibly kill your MPPT.

The maximum input voltage is generally accepted as a hard limit, never to be exceeded. Of course, there is headroom built-in to the design to account for component variations but if you get a unit which has input FETs at the low end of their spec. then that headroom is eroded.

 

[zenniz]

P = IV
You need voltage and current to generate power.

In solar PV modules:
Current is proportional to the amount of sunlight that the panel receive.

Voltage is always there regardless if there are any load or sunlight.

At night, panel will still produce voltage but current is 0 because there is no sunlight. P = IV = 0W.

Solar PV modules is sensitive to temperature. The electrical parameter (Voc, Isc, Vmpp, Impp, Pmpp) that you see in the panel datasheet are always tested at cell temperature of 25 degree.c. If cell temperature goes lower than that, voltage will increase over whatever you see in datasheet.

If you size just slightly below the inverter's maximum allowable input voltage without considering temperature changes throughout the day, there will be a chance that it will damage your inverter due to over voltage especially during winter time.

 

[SomethingAppropriate]

Voltage is always there regardless if there are any load or sunlight.

Very important point here. You still can get shocked when you think "there isn't any sunlight left." or the panels are producing nothing.

 

[SomethingAppropriate]

I thought this might be the case. Could you please explain why this is?

This only applies to a situation like yours with 1 panel or a non-parallel setup.

Lets say your panel outputs 8 amps and you have a 15 amp fuse on it.

How would that panel produce more than 10 amps? It wouldnt.
Its like a hose and the current is proportional to the size of the hose.

You can only get so much out of it.


Now if you had 3 panels in parallel and one shorts internally then you could have 24 amps going to it as it grabs all of its neighbors current and converts it into fireworks. That is when you need a fuse.