Current setup is Goodwe ES, 2 strings of 6x325W Risen panels, Freedom Won 10/8. This system is really under panelled, especially when weather is margingal. One string faces North, one East. I have lots of East/West facing roof, not so much North. I’m in Randburg, Gauteng.
So what I want to do is
Replace the North facing string with 550W or thereabouts panels.
(optional) move the 325W panels that are currently facing North to face East.
(1) would mean using the existing wiring and mountings. The MMPT can take it, and I understand that you are installing panels and not running or configuring the inverter. I’ve lived with that inverter since 2019 and I can control it. What I want to do now is to give myself a bit more production on days when the sun is shining but not at it’s shiningest.
(2) would mean some extra wiring and mountings.
So please consider this a request for quotes. You can come and inspect if you want. DM me. I think you should be able to give a price for (1) because all the wiring, the circuit breakers, the mounting brackets are already there. You’re just going to take the old panels off and mount the new ones.
DMs please. We don’t need to clog up the forum with our hagglings and my answers to your questions.
Unless your existing rails are much larger than what’s required for the existing panels, you will most probably need to change / extend them as the 550w panels are a bit wider. Most probably need to move one rail up or down since the panel is longer as well and panels have a recommended mounting spot.
That inverter only has 2 mppt so how are you going to add a third optional string. Maybe look at a separate string / micro inverter
Thanks. The panels are mounted on a pair of rails, the rails are wider than the panels, so I have some space horizontally. But this is why I deal with people with expertise rather than do a DIY. They will spot details that never occured to me.
The new panels will not be a problem because they are replacing existing panels.
For the option, I am thinking - possibly incorrectly - that it will be possible to form one array of 12 panels and feed that into one MMPT. The two pieces of roofing involved are the same angle and parallel to each other.
If it can’t be done then that’s not a deal breaker.
Don’t do less than 8x 550w panels on a string on this inverter. Preferably more. Ask me how I know. The amps on these panels are too low for the MPPT to use them to their full strength. So having more will assist to overcome that weakness.
I currently have 6x 535w and this inverter struggle with that string. The string with 9x 330w panels on, in comparison generates tons more most of the time.
Oh pooh. There is a bit of room to spare, but I don’t think I will get 8 up there without some some shading.
I have very little North facing roof. Lots facing East and West. I have room for a whole other string of East (or West) facing panels, so I could go to 12 X 325.
Again, this is why I have to invoke people who actually know what they’re doing.
OK… please remember that I can’t spell “elektrishen”.
The Risen specs say 8.7A at full power, and 7.09 at normal operation.
For Canadian 550W the figures are 14 and 10.55. So this looks to me like more juice per panel. Or is that they get connected differently and so the TOTAL available current is too low?
Voltage or amps. I may have been wrong saying amps. The voltage on my 535w string is too low most of the time.
On my 330w string the voltage is regularly around 300-400v and they work great. The 535w string generally goes to 250v and doesn’t go higher than that but also at times will be lower. Anything from 200-250v. You can have a look at the inverter’s ideal voltage range as opposed to the full spectrum it supports.
Looking at the graphs now, it has to be the voltage that I meant. Amps, the 535w string is around 8amps and the 330w string at around 7amps.
Either way it’s not a major issue. There are rail extenders for most branded rails.
Looking at the inverter specs, it is able to handle 14A per mppt with a max short circuit current of 17.5A. With the Sunsynk inverter, it will just limit to the max current. Goodwe should be the same but perhaps someone else that has worked on this inverter can confirm. So your 2x7.09 should be close if you parallel them From what I’ve seen, current can be exceeded but voltage should never be otherwise you see the smoke.
East -west works great in summer months but really struggle a lot in winter because of the lower sun angle. So get as much as you can on the north array.
On all panels, the larger current number is short circuit current, under max power, you will generally see the Imp which in this case is 10.55A. If it’s connected in a single string, the current is the Imp at max power. For parallel strings, take the Imp of a panel and multiply by the number of parallel strings.
Definitely voltage. But the specs on the inverter say that the moot range is 125V to 550v. Too close to the 125 and you will find that production drops off a lot. 5 or more in series should be fine.
Yip. While 125v may be the minimum on paper, and theoretically should be fine, my experience with this string and this inverter, is that 250v doesn’t work optimal. Not even great. I’d classify it as, barely works most of the time.
The string pushing more than 350v most definitely works A LOT better. Optimal even most of the time.
If I knew this, I would have probably made a different choice of panels on my 2nd string. Is all I am saying, in regards to the inverter in use by the OP.
That is very strange. My experience is that these inverters work perfectly with 6 panels (~50V/panel), even down to 4 panels. When you go above 8 panels, the MPPT starts doing strange things sometimes, but you won’t notice unless you are logging fast enough.
Since everyone is mentioning volts and amps and string length: Do check the amps when fitting new panels on old inverters. Some panels have a peak current that exceeds what the inverter can handle.
Most inverters can handle a peak that is slightly higher than the maximum power level they will run at (losing a small bit at the top). That is another thing to consider.
This may affect your choice of panel.
As for the length of rails, if you stick with the same rail (eg Renusol or whatever you used), accessories are available to extend the rail, so you can add a few roof hooks and a short length of rail, and Bob’s your uncle… unless you are Bob, then you are the uncle.
I suspect that something I long suspected is true.
Getting somebody to install a system: Easy
Getting somebody to modify an existing system: Nobody interested.
There’s a lot of systems out there now that are a couple of years or more old and that need some sort of tweaking. But nobody seems interested in that. Maybe understandable, because there will always be a tendency to blame the last person who touched the system for all and any problems thereafter.
I think thats the issue: An upgrade is full of unknowns.
I would sell the current system and then get a full new (fully compatible/designed) system installed. It may be even cheaper that way and warranties/COC’s will be in place.
I left my whole system behind when I moved specifically due to the hassle of uninstalling and reinstalling.
I know of a Victron Multi RS 6 kW inverter, 10 kWh batteries and 8x 550W solar panels currently for sale, 5 months old.
Just saying.
I however agree with what you say about your Freedom Won, though there’s no reason to change it. Getting a newer inverter which can support higher input panels, is not such a bad idea though.
I just checked the data sheet I got with the inverter.
Max DC input power: 6500 W (it’s not clear if that is per MPPT or total)
Max DC input voltage: 58
MPPT voltage range: 125 ~ 550
Voltage range full load 170 ~ 550
Nominal DC input voltage: 360
Max input current: 11/11
PV overcurrent protection: 21
I’m assuming these are effectively per MPPT. Otherwise you can have 6400 on one and 100 on the other. Also the heading is “PV string input data” and they stipulate 2 MPPT with 1 string each.
Maybe if I only had 1 string running at 250v? The strange thing is, even if I swap the 2 strings between the PV1 and PV2 port on the inverter, the same behavior keeps happening, just now on the other port of the inverter. And, I have done multiple firmware updates on this inverter, it never changed this behavior.
Anyways, maybe it is just my specific setup that is not ideal. I just wanted to make sure someone else don’t end up with the same problem as me. I know Bobster has the same inverter as me.
As this is a Goodwe we’re talking about, it could also be a firmware issue. I have had Firmware upgrades that make quite a difference to how the system behaves.