According to the Goodwe specs the max DC voltage allowed  is 580V .(See attachment)

The specs also state that one can have a maximum of 6500W PV Input  and 11 A on each of the 2 strings (1 on each MPPT controller)

With a 405W Panel, Voc of 44.4 V, according to this website , one can only have a max of 13 panels, which is nowhere near 6500W total.

If you have 8 panels in each string, the DC voltage max would be 2 X 377V which is greater than the 580 V allowed.

https://gold-coast-solar-power-solutions.com.au/solar_power/solar-panel-maximum-voltage-calculator/

So the question is , is the 580V per string or for the 2 strings combined?

 

 

1 hour ago, FixAMess said:

So the question is , is the 580V per string or for the 2 strings combined?

Per MPPT. 

 

2 hours ago, FixAMess said:

According to the Goodwe specs the max DC voltage allowed  is 580V .(See attachment)

The specs also state that one can have a maximum of 6500W PV Input  and 11 A on each of the 2 strings (1 on each MPPT controller)

With a 405W Panel, Voc of 44.4 V, according to this website , one can only have a max of 13 panels, which is nowhere near 6500W total.

If you have 8 panels in each string, the DC voltage max would be 2 X 377V which is greater than the 580 V allowed.

https://gold-coast-solar-power-solutions.com.au/solar_power/solar-panel-maximum-voltage-calculator/

So the question is , is the 580V per string or for the 2 strings combined?

 

 

When you series your 8 panels the VOC ads up so 44.4x8=355V. Now when you use 2 seperate mppt's the strings stay seperate as the mppt's function individually. So Jaco is correct, the volts is per mppt in this case.

Even if you were using a single mppt the answer would have been the same. When you series connect panels/strings the Volts go up and the Amps stay the same. When you parallel connect panels/strings the Volts stay the same and the Amps go up.  So even using 1 mppt with 2 strings of 8 panels the Volt would still be 355V and not 710V. In the case of the Goodwe the mppt would handle the Volts of 2 strings but not the Amps.

1 hour ago, Jaco de Jongh said:

Per MPPT. 

 

Good, thanks. I originally planned to install 16 panels, 2 strings of 8.

I've only installed 15 so far. I'm thinking of installing another 3, which is then 7290 W of panels. If by a miracle I get max 90% of rated power, on a cloudy day, that gives me max 6561 W, DC, which is above the 6500 W DC spec of the inverter. 

Your thoughts on the above? Am I maybe pushing my luck adding the extra 3 panels? 

Edited April 10, 20206 yr by FixAMess

10 minutes ago, FixAMess said:

I've only installed 15 so far. I'm thinking of installing another 3, which is then 7290 W of panels. If by a miracle I get max 90% of rated power, on a cloudy day, that gives me max 6561 W, DC, which is above the 6500 W DC spec of the inverter. 

The output of the inverter switches off very quickly if it sees to much PV coming in. During summer months in Gauteng being rainy and partly cloudy I seen units switch off regularly for up to 15 minutes from the effects of Cloud edge effect. That was on arrays of 6400whp and below. 

I would suggest you lay off the oversizing for at least a year to monitor how your system performs. 

 

I went back and checked, max power to date is 5946W on an installed 6075 W,so > 95% is possible, even if it's just momentarily. 

Maybe time to look for a Victron... 

 

I have a Goodwe myself with 5500W on the roof. It happens quite often that the generation is more than 5500W. Best so far 5650W.  I am very happy with my Goodwe. My max daily generation is 34.5kW so far with 30kW+ a regular occurrence.

 

I install Victron as well and for sure better than Goodwe but for now I will not spent money to change from Goodwe to Victron except if I want to go bigger than my current setup. 

14 hours ago, pvdw22 said:

I have a Goodwe myself with 5500W on the roof. It happens quite often that the generation is more than 5500W. Best so far 5650W.  I am very happy with my Goodwe. My max daily generation is 34.5kW so far with 30kW+ a regular occurrence.

 

I install Victron as well and for sure better than Goodwe but for now I will not spent money to change from Goodwe to Victron except if I want to go bigger than my current setup. 

Where are you situated? I'm in  Edenvale, East of JHB. 

On a sunny day, in April, I'm getting 28KW, peak, getting to be winter sunshine. 

I'll see how winter goes and revisit next year. 

 

37 minutes ago, FixAMess said:

On a sunny day, in April, I'm getting 28KW, peak, getting to be winter sunshine.

Do you mean you get 28 kWh?

 

15 hours ago, Jaco de Jongh said:

The output of the inverter switches off very quickly if it sees to much PV coming in. During summer months in Gauteng being rainy and partly cloudy I seen units switch off regularly for up to 15 minutes from the effects of Cloud edge effect.

Why isn't this inverter simply "clipping"? It should not switch of in my opinion but only take as much from the PV power as it can handle and not use any more available than that.

It should look something like this:

But since Jaco has seen the inverter switching off I wonder if this is normal behavior for this type.

4 minutes ago, RikH said:

Do you mean you get 28 kWh?

 

Why isn't this inverter simply "clipping"? It should not switch of in my opinion but only take as much from the PV power as it can handle and not use any more available than that.

It should look something like this:

But since Jaco has seen the inverter switching off I wonder if this is normal behavior for this type.

Yes, 28KWh, measured over sunlight hours.....

The issue I have with the Goodwe is that it does not allow for much control over the batteries. E.g, I'd like to limit charging to 95% only, which it cannot do.

For a home installation the Goodwe is an excellent choice, simple, reliable, good backup service and it supports many battery types, so I cant really complain.

1 minute ago, FixAMess said:

The issue I have with the Goodwe is that it does not allow for much control over the batteries. E.g, I'd like to limit charging to 95% only, which it cannot do.

Is the inverter getting it's information direct from the battery BMS (via CAN or whatever) or is it just sensing the voltage?

BMS.. It's all working perfectly, as designed, but does not have many control parameters that can be set like the Victron. 

I added a 3rd us3000 battery last week. Top balanced them by connecting in parallel and after 2 days of use they all balanced to 100%SOC,so the BMS works well. Initially they only got to 98% SOC before one of the batteries logged an over voltage warning. After a few charge, discharge cycles, only down to 50% DoD, they all came up to 100% SOC. 

 

5 hours ago, RikH said:

Why isn't this inverter simply "clipping"?

That was my question as well. Seems like it cant do it and then to protect itself, it rather switches off. 

I have asked the same question a few times, but received noclear answer. 

19 hours ago, Jaco de Jongh said:

Seems like it cant do it and then to protect itself, it rather switches off.

Or is it getting to high voltage?

I've been monitoring my 2 strings. The total v has never gone higher than 580v..

What seems to be happening is that a string current  is "throttled". E.g,2 strings, similar size, same sunlight, once pushes 8 amps, the other only 2...They track each other perfectly, Amps until the voltage gets too high and then 1 is throttled.... Not sure how this works but it's what I've seen... 

23 hours ago, FixAMess said:

After a few charge, discharge cycles, only down to 50% DoD, they all came up to 100% SOC.

Yeah but you want to go to 95% I understood. Why? You want to expand the life of these batteries I guess? Well it looks like that's not possible with your gear but you shouldn't be to worried about that, my understanding is that these Pylons are good batteries.

8 minutes ago, FixAMess said:

What seems to be happening is that a string current  is "throttled". E.g,2 strings, similar size, same sunlight, once pushes 8 amps, the other only 2...They track each other perfectly, Amps until the voltage gets too high and then 1 is throttled.... Not sure how this works but it's what I've seen... 

What you are describing here is clipping.

On 2020/04/11 at 9:25 AM, FixAMess said:

Where are you situated? I'm in  Edenvale, East of JHB. 

On a sunny day, in April, I'm getting 28KW, peak, getting to be winter sunshine. 

I'll see how winter goes and revisit next year. 

I am in the northern parts of Pretoria

On 2020/04/11 at 9:25 AM, FixAMess said:

 

 

7 hours ago, RikH said:

Or is it getting to high voltage?

I think  to high amps. The string voltages were in the mid 300s

On 2020/04/12 at 12:20 PM, FixAMess said:

I've been monitoring my 2 strings. The total v has never gone higher than 580v..

What seems to be happening is that a string current  is "throttled". E.g,2 strings, similar size, same sunlight, once pushes 8 amps, the other only 2...They track each other perfectly, Amps until the voltage gets too high and then 1 is throttled.... Not sure how this works but it's what I've seen... 

Update;

I had a chat with the Goodwe tech guy.

The max V is 580/string (safety margin) but should not exceed 550V/string (Maximum working voltage), optimal operation is at 360V/string.

Maximum power is 3200W per MPPT , total = 6400W which then results in a max of 5200 W AC power being generated.

Plugging all relevant info into this calculator, gives you 8 panels in a string at max 380V (2' Celsius), and 3200W peak power...

https://gold-coast-solar-power-solutions.com.au/solar_power/solar-panel-maximum-voltage-calculator/

Ideally one would want to keep the DC output at as close to 6000W as possible, in both summer and winter, clouds etc. but would then have to put a tool of some sort between the inverter and the panels to limit the DC power being fed back into the inverter.

 

@FixAMess do you have any insight on why resultant wattage is 5200W AC. Just for my knowledge.

 

I have 15 * 435W panels on my roof in a 8 + 7 configuration which comes out at 6500watts. My inverter seems to throttle to 5200w with occasional spikes over. Is this normal?

 

 

Hi,

Are you talking about panels Watts at 5200W or AC produced by the inverter?

The max power that the inverter can put out in AC is 5100W (Excluding pass through), so if you are generating 5200W AC then you are on the edge of the designed capacity.

Nominal output is 4600W AC (excluding pass through power).

The 6500 panel Watts is already oversized by 30% (compared to 5000W of inverter AC output), so if you're talking about the PV panels producing 5200W then you're doing pretty well;  5200W produced/6500W installed = 80% of installed panel power, on my installation I'm getting 79% in summer.

Check the current / voltage on each MPPT, you will see that its probably running close to 11A on each string, hence the "throttling"...

I've seen mine spike as well and then the inverter seems to bring it back to 4800W panel power.

The MPPT's are optimized/designed (??) to produce the max power at 360V.

Remember that the heat of the panels and the inverter temperature will also impact the power produced. Generally, a cool day with lots of sun produces the most power.

An easy way to see if you are in the "sweet" production curve is to see if you are producing 4-6 X installed total PV, 4 in winter 6 in summer.

So with 6500W panel power installed, you should be getting close to 36-39kW/day. (if the sun shines, not too hot, no dust, clouds, no bird crap all over the panels).

The power produced by the inverter will follow the load and may then also add additional grid power to get to the 5200W. So if your house load is 4500W (lets pretend) and your panels are only producing 2000W at 8am, the rest will come from the grid, so your total power will follow the load (unless youre feeding the grid, in which case you can produce to the max capacity of the inverter)

The Goodwe is really a beautiful, reliable, no-fuss, simple inverter, no complicated configurations.

 

Edited November 11, 20205 yr by FixAMess

i have to agree with @fixamess, the goodwe is really a carefree inverter for the novice user, making for an easy installation.... and it is very efficient and can handle quite some nasty loads without problems.... you can oversize quite a bit... i have 22 x 330watt panels installed, totalling a theoretical value of 7260watt... and i constantly get around 5900-6200watt during peak producition which goes or equates to between 80-85% efficiency... during the week i actually had the inverter hit over 7000watt producing stable for over 20mins... this week has had lots of cloud cover so i am sure the panels was quite cool due to cloud cover and low production with the sun breaking through causing this anomoly... however is still pretty impressive.... since my best numbers is normally in december only......

What is your Voc for those 330W panels?

Each mppt produces 3200W max, so 6400W total..7000W is pretty impressive..

 

6 minutes ago, FixAMess said:

What is your Voc for those 330W panels?

Each mppt produces 3200W max, so 6400W total..7000W is pretty impressive..

 

The inverter will generate 6400W when its charging batteries and feeding the balance to the grid. So on the AC side you are limited to around 5kW; when charging batteries as well the MPTT will go up more because that’s on the DC side