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Minimum PV Voltage with Growatt 5000 Inverter

Bananassassin

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I have 2 Growatt 5000's that I just installed. My primary goal is power storage for when the grid fails (I'm in Texas so, yeah). I have no PV panels yet, I'm just charging off the grid for now. I want to add some solar in the new year. I'm going to start small - real small, like 1 or 2 panels just as a proof of concept. It will also provide some minimal generation to prolong the storage I get from my 4, 48V 100AH rack batteries. Anyway...how small can I go? The specs on the inverter list 150VDC as the start-up voltage. Forgive my rookie question, but I'm assuming I can't just get a couple 12V panels and get a pulse? Do I really have to start with 150V to get the inverter to acknowledge a PV source?

Thanks in advance!
 
Generally speaking, a lot of panels have a voc near 40v. Four in series would get you around 150v. Five even better.

If you were doing a 12v system I could see 12v panels, but in this case; 48v battery bank, IMO, regular panels would be a better choice.
 
The SPF 5000 ES has a fairly high voltage PV input, so a couple of small panels is not going to get it to turn on.

The manual says:
1641075543885.png

So you should plan on getting at least 160V for Voc.

Most decent-sized panels are running at 35-40V so probably a minimum of 4 or 5 decent-sized panels just to get it started.

If you buy 4 or 5 panels..... are you sure you are going to be able to find more of the same panel later. The panels seem to change pretty quickly and a year after you buy them they are not available any longer.
 
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Does Growatt SPF 5000 ES have mppt reverse polarity protection? I just have connected a 34 volts pv panel and nothing was shown as pv voltage on display. I though I may had reversed polarity, because DC breaker is + -,- + and I connected according to it.
 

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Thanks, I realised I made a mistake. Then I connected in normally - right side of DC breaker + with red cable that goes to pv positive terminal of the inverter and left terminal of DC breaker to negative pv terminal of Growatt. But again the inverter doesnt show pv input voltage on LCD display. Maybe that's because PV panel has only 34 volts and they are lesser than battery 48 volts?
 

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Be very careful about how polarized breakers are used.


The problem is that the polarized breaker has arc quenching techniques that only work when the current is flowing in one direction. If the breaker trips or is manually opened when the current is flowing in the other direction the arc is not quenched. (I don't know for sure, but it is conceivable that the Arc Quenching might even make things worse if the current is flowing in the wrong direction)

A polarized breaker between the charge controller and the solar array can be set up to work correctly and safely. However, never use a polarized breaker as the string Over-current-protection device. Either direction a polarized breaker is set up would have a problem. The over-current protection devices on a PV string is there to protect against the current from the *other* strings. Therefore, to meet this need the breaker must be installed with the positive away from the panels on the string. However, if you do this there is a significant fire risk if you manually turn the breaker off.

More about this can be found here:

*** Note: I have seen circuits that use polarized breakers like this:

1655583847291.png
The idea is that no matter which way the current is flowing, one of the two will extinguish the arc. While that seems theoretically correct, I have never felt like this was a good way to go.
 
The SPF 5000 ES has a fairly high voltage PV input, so a couple of small panels is not going to get it to turn on.

The manual says:
View attachment 77979

So you should plan on getting at least 160V for Voc.

Most decent-sized panels are running at 35-40V so probably a minimum of 4 or 5 decent-sized panels just to get it started.

If you buy 4 or 5 panels..... are you sure you are going to be able to find more of the same panel later. The panels seem to change pretty quickly and a year after you buy them they are not available any longer.
I have 5 pannels 535w installed its not possible to install 545s later?
 
I can't just get a couple 12V panels and get a pulse? Do I really have to start with 150V to get the inverter to acknowledge a PV source?

Thanks in advance!
Don't waste your time getting enough 12V panels to make this work. You are in Texas, one of the most solar prolific locations in the country. Go on Craigslist for your nearby city and see what is on sale locally. Buy panels locally, with in-person pickup instead of shipping, and you will save a lot of money.

Here's what I found in just 30 seconds of searching.
You might not be anywhere close to Dallas, but this gives you an idea of the prices you can find. Five or six of these panels in series would be what you need, so for no more than 450$ you'll have enough solar to bring the system online. 1500W should give you at least 3kWh even in December. A lot more if you can mount them on a rotating mount like this. This mount can hold six grid-tie panels when mounted in landscape orientation. I'd expect one array like this to make you >7.5kWh of power in the summer, just facing south. Almost double that with manual tracking.
 

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Hi guys,

I have the SPH 3600. Are there any possibilities the change the minimum voltage of 150, e.g. by firmware settings?

Thanks for any hints!

Best regards,
Toby
 
Hi guys,

I have the SPH 3600. Are there any possibilities the change the minimum voltage of 150, e.g. by firmware settings?

Thanks for any hints!

Best regards,
Toby
Most likely not easily. Anything can be changed if you're willing to modify it enough, but I see that limit probably also being embedded in the hardware somewhere as well.

Starting another thread would be the best way to get a more precise answer, most people won't see your post here.
 
The SPF 5000 ES has a fairly high voltage PV input, so a couple of small panels is not going to get it to turn on.

The manual says:
View attachment 77979

So you should plan on getting at least 160V for Voc.

Most decent-sized panels are running at 35-40V so probably a minimum of 4 or 5 decent-sized panels just to get it started.

If you buy 4 or 5 panels..... are you sure you are going to be able to find more of the same panel later. The panels seem to change pretty quickly and a year after you buy them they are not available any longer.

How does the voltage scale for panels? I'm looking at panels with 41-44 VOC and "Voltage at maximum power" 38, but not sure how much voltage they'd offer under partial sun, like morning-afternoon.
 
How does the voltage scale for panels? I'm looking at panels with 41-44 VOC and "Voltage at maximum power" 38, but not sure how much voltage they'd offer under partial sun, like morning-afternoon.
Generally speaking current varies with sun angle, shading, etc. while voltage holds pretty steady.

Voltage does change with panel temperature, so you have to do a little math to make sure you stay within the min/max ranges on very cold and very hot days.
 
Generally speaking current varies with sun angle, shading, etc. while voltage holds pretty steady.

Voltage does change with panel temperature, so you have to do a little math to make sure you stay within the min/max ranges on very cold and very hot days.

I'm interested to know how many panels I'd need to get the beast going. Would 6 be enough in the morning/afternoon?

Presuming a rotating/tilting support for optimum angles.
 
Four of those 40+ Voc panels should in theory start it most days, but I'd want 5 or 6 in series to have some margin for hot days and such.
 
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