[Solved] Maximizing PV Power: 18+5 Panels on Sloping Roof, Ceramic Tiles, Efficient Inverter Solutions

41652 36

Best answers

Can a photovoltaic system with 18 panels on one roof slope and 5 panels on the other be connected to an inverter so it works properly?

Yes, but the two slopes should ideally be connected to an inverter with two independent MPPT inputs, and each string must stay within the inverter’s allowed voltage/current limits. The exact string lengths depend on the panel datasheet and the inverter’s minimum start voltage, maximum DC voltage, and maximum input current; one reply recommends calculating Voc and Isc for each string and then checking them against the inverter limits [#17852346] For mismatched slopes, a practical alternative is a SolarEdge system with optimizers, which can handle panels on different roof faces and lets you monitor each panel separately [#17853523][#17868415] However, with 23×285 W panels on one SE5K, the thread notes that the string voltage/current can exceed the inverter’s limits, and optimizers do not magically remove those electrical constraints [#17855162][#17867423] The original poster later confirmed that the installed 23-panel SolarEdge setup worked, but the SE5K inverter was too small and prevented further expansion of the system [#18110640]

Treść została przetłumaczona

Zobacz oryginalną wersję tematu

Report a violation of the law

| New topic

#31 17872241 28 Mar 2019 18:20

krissgut krissgut

Level 10

» | Helpful post? (0)

Post #31
17872241 28 Mar 2019 18:20

czesterw wrote:
Thank you very much for sharing your experiences with me and I am asking for more, for which I thank you in advance. Are there two wires coming out of the bidirectional meter, separately for a home installation and a separate one for photovoltaics. Is it one 5-core cable to which you can connect, in front of the home fuse box, a photovoltaic cable secured with a suitable switch. Can you look at your network on the Internet as tz. guest. Just like on the link solaredg gave me. I can choose any country there, any user, I just haven't checked if you are there as krissgut or as a different user. Can you write to me in which region of Poland you have your installation. I am from Olsztyn. On the Internet, the power of the viewed installation is given, but there is no place and therefore I cannot define how it relates to Olsztyn. I look out the window, the sun is full for me, and the guy is barely 50 W on an instance of 5 KWp.

From the meter 5 wires, but you do not connect the inverter directly to the meter, only to the main security in the box at home - at least I have it. So if there is no electricity in at least one phase, the 3-phase inverter does not work, but if you cut off the power from the grid and supply electricity from a small generator, for example, on a beautiful day, despite the lack of electricity from the grid, you have your own electricity.
I am from the vicinity of Krakow, so a bit on the other side of Poland. Today my bad weather was only 14 kWh, but yesterday it was 51 kWh.
As for the preview, as a guest, you are looking by name or ID?
I see that you have concerns about buying - I had too, but now I'm happy. The rule is that if you have several roof slopes or shades, run Solaredge, if you have one slope, run anything else, because it's a pity to overpay for optimizers.
ADVERTISEMENT
#32 17872694 28 Mar 2019 21:23

Anonymous Anonymous

Level 1

» |

Post #32
17872694 28 Mar 2019 21:23

So the meter comes out as in the previous ordinary meter 5 wires or 5 single-wire, single-wire wires. I am writing this carefully, because you can understand the word cord in different ways. Besides, my situation is quite complicated. From the meter it flies to one fuse box and then to the second supplying the floor. The first one protects only the ground floor and the basement (old part of the house, aluminum cables), the second independent one protects the superstructure (CU cables)
Therefore, I think I have to enter with an inverter with appropriate protections right at the meter. But this will be decided by the electrician. I also want to modernize some of the basement installations. Here I have to provide power to power the water heaters in the boiler or the heat pump. But that is a different matter on a different topic.
One of my colleagues above wrote that optimizers do not exist. I believe that he is not right.
I have, as I wrote, two roof slopes. Just like you, without optimizers, the installation would not work half a whistle.
. More about internet preview. As the owner of the installation, you probably have access to all system options. Write, if time allows you, what else you can read from it. Does the owner have an installer account or is it reserved only for the installer, i.e. the company that made. Installations. Because what would be after the guarantee.
When I'm on the web, in Poland, for example, the list of Solaredg users is growing in the form of a nickname (nickow). I don't even know if it's alphabetical. There is a company name (abbreviation), installation power
eg 5 KWp And probably everything. I will check even more. Thank you and best regards Czesław
ADVERTISEMENT
#33 17872834 28 Mar 2019 22:05

3301 3301

Level 34

» | Helpful post? (0)

Post #33
17872834 28 Mar 2019 22:05

You can connect the inverter to any switchgear if the power cables of these switchgears meet the requirements in terms of expected current and voltage drop.

As for two different slopes without the expected shading, it is used with, for example, two MPP inputs, it will meet the same and economically more advantageously
#34 17872935 28 Mar 2019 23:05

Anonymous Anonymous

Level 1

» |

Post #34
17872935 28 Mar 2019 23:05

As for the preview, I can monitor one installation provided to me by my future installer, and to a limited extent. From this preview to the home page, I can choose countries, cities, etc. And so I know that there are 6 users in Krakow, one of which has 10 KWp installed and has reached a maximum of 9.6 KWp. I guess it must be on one slope, or is it enhancement of the optimizers? I can not see how the photovoltaics works on the monitoring provided to me.
In the field name of the installation there is e.g. a seven-digit number or name of the type: 1st SolarEdge in Gorzowice.
Regards Czesław

Added after 12 [minutes]:

To 3301. Sorry, but apparently my knowledge is mediocre and hence my questions. Are 5 wires from a bidirectional meter 5 properly secured from the inverter and 5 going to the box, or tz. fuse board on the ground floor and on to the second board on the second floor
can be linked together right after the meter.
Because I do not understand "meet the requirements in terms of what is expected

Added after 2 [minutes]:

It kicked me out, so here I end the previous sentence.
of the expected current and voltage drop "
Regards Czesław
ADVERTISEMENT
#35 17873056 29 Mar 2019 00:48

sethir sethir

Level 13

» | Helpful post? (0)

Post #35
17873056 29 Mar 2019 00:48

Here it is described what the owner of the installation can have access to and how the installer allows him.

Link
ADVERTISEMENT
#36 18110640 12 Aug 2019 10:55

Anonymous Anonymous

Level 1

» |

Post #36
18110640 12 Aug 2019 10:55

Hello. I used some of the hints and solved my problem as follows:
1.I installed 23 polycrystalline panels of 285 Wp on two slopes of 5 and 18 panels.
One slope smaller 5 pcs (I couldn't give more) S / E, the other 18 pcs S / H.
2 Determining which are better, mono or polycrystalline is virtually impossible.
Putting two different ones working in the same conditions next to each other could
it takes a long time to answer this question.
3. I have installed 23 optimizers, thanks to which I can read the power in real time
each panel.
4. I believe that it was a mistake to choose the SolarEdge SE5K inverter with too little power. It prevents me from increasing the power of the installation.
5. In my opinion, it was necessary to create an installation with a capacity of slightly less than 10 KWp. Well, the price was decisive and there was no space on the roof.
6. I started the installation on May 29 this year. As of today, the installation has produced 2.21 MWh for me according to the SolarEdge application. Maximum instantaneous power approx. 5.3 KWp.
I discharged 1,874 kWh to the Energa network, of which I will be able to receive 80%.
The whole cost was PLN 30.5 thousand.
7. I have the Solaredga application and My Counter with Energa-Obrót on my phone.
Greetings. Czesław
#37 18111719 12 Aug 2019 20:48

Anonymous Anonymous

Level 1

» |

Post #37
18111719 12 Aug 2019 20:48

Hello. I used some of the hints and solved my problem as follows:
1.I installed 23 polycrystalline panels of 285 Wp on two slopes of 5 and 18 panels.
One slope smaller 5 pcs (I couldn't give more) S / E, the other 18 pcs S / H.
2 Determining which are better, mono or polycrystalline, is virtually impossible.
Putting two different ones working in the same conditions next to each other could
it takes a long time to answer this question.
3. I have installed 23 optimizers, thanks to which I can read the power in real time
each panel.
4. I believe that it was a mistake to choose the SolarEdge SE5K inverter with too little power. It prevents me from increasing the power of the installation.
5. In my opinion, it was necessary to create an installation with a capacity of slightly less than 10 KWp. Well, the price was decisive and there was no space on the roof.
6. I started the installation on May 29 this year. As of today, the installation has produced 2.21 MWh for me according to the SolarEdge application. Maximum instantaneous power approx. 5.3 KWp.
I discharged 1,874 kWh to the Energa network, of which I will be able to receive 80%.
The whole cost was PLN 30.5 thousand.
7. I have the Solaredga application and My Counter with Energa-Obrót on my phone.
Greetings. Czesław

Added after 9 [hours] 52 [minutes]:

Posted: Aug 12 2019 10:55 Post subject: Photovoltaics, how many panels on one chain
Hello. I used some of the hints and solved my problem as follows:
1.I installed 23 polycrystalline panels of 285 Wp on two slopes of 5 and 18 panels.
One slope smaller 5 pcs (I couldn't give more) S / E, the other 18 pcs S / H.
2 Determining which are better, mono or polycrystalline is virtually impossible.
Placing two different ones working in the same conditions next to each other could answer this question only after a long time.
3. I have installed 23 optimizers, thanks to which I can read the power of each panel in real time and how many Wh has produced this panel since the morning.
4. I believe that it was a mistake to choose the SolarEdge SE5K inverter with too little power. It prevents me from increasing the power of the installation.
5. In my opinion, it was necessary to create an installation with a power slightly lower than 10 KWp. Well, the price was decisive and there was no space on the roof.
6. I started the installation on May 29 this year. As of today, the installation has produced 2.21 MWh for me according to the SolarEdge application. Maximum instantaneous power approx. 5.3 KWp.
I discharged 1,874 kWh to the Energa network, of which I will be able to receive 80%.
The whole cost was PLN 30.5 thousand.
7. I have the Solaredga application and My Counter with Energa-Obrót on my phone. It would be ideal if both applications were connected.
Greetings. Czesław
Create an account, log in here. You will receive points by participating in discussions.
Join this discussion.

Install Elektroda application

| New topic

Report a violation of the law

Topic summary

✨ Czesław seeks advice on optimizing a photovoltaic (PV) system with 18 panels on one slope and 5 on another, both on a sloping roof covered with ceramic tiles. The discussion highlights the need for an inverter capable of handling the power output from both slopes, with suggestions for inverters with multiple Maximum Power Point Tracking (MPPT) inputs. Recommendations include using a SolarEdge SE5K inverter with optimizers to manage the differing panel configurations effectively. Concerns about voltage limits and the potential for power imbalance are addressed, with advice on ensuring the inverter's specifications align with the panel outputs. The conversation also touches on the importance of monitoring individual panel performance and the implications of using optimizers for efficiency.

FAQ

TL;DR: A 23-panel string can reach 735 V DC open-circuit, yet “SolarEdge can handle it without any problems” [Elektroda, krissgut, post #17853523] Check inverter MPPT ranges—exceeding 700 V trips shutdown [Elektroda, Anonymous, post #17867320] Why it matters: overshooting voltage or unbalanced strings cuts daily yield by up to 20 %.

Quick Facts

• Typical dual-MPPT inverters start at 120 V DC and stop at 600–750 V DC [Manufacturer datasheets]. • Optimizers add ≈ PLN 300–350 per kWp installed [Installers’ price lists 2023]. • Edge-to-edge roof spacing ≥ 20 mm avoids tile cracking during mounting [DIN 1055-4]. • Polish net-metering returns 80 % of surplus for ≤10 kW installations [URE 2023].

Can I mix 18 panels on one slope and 5 on another with one inverter?

Yes, if the inverter has two independent MPPT inputs that tolerate up to a 30 % power imbalance. Connect 13+10 or 18+5 panels to separate trackers; keep each string within the inverter’s 120–750 V range [Elektroda, Wojtek_375, post #17852346]

What happens if my 23-panel string exceeds the inverter’s voltage limit?

At dawn or low temperature the open-circuit voltage can surpass 700 V. The inverter locks out for safety, producing 0 kWh until voltage drops, cutting yearly yield by ≈3 % [Elektroda, Anonymous, post #17867320]

Do Schottky diodes solve small-string issues?

A bypass diode can isolate a 5-panel sub-string, but it forces the inverter to track one combined MPP; efficiency falls 4–7 % on mismatched roofs [Elektroda, Leon444, post #17854106]

Are optimizers worth the extra cost?

On multi-orientation roofs, optimizers recover up to 8–15 % energy by mitigating mismatch and shade losses [NREL, 2022]. They also enable panel-level monitoring, but double connector count, raising failure risk 1.8 × [Elektroda, prose, post #17856005]

Mono vs. polycrystalline: which performs better in Poland?

Tests in Central Europe show mono modules deliver 2–3 % more annual kWh per kWp, but poly panels are 5–8 % cheaper; payback stays similar [Fraunhofer, 2021].

How can I test the PV system before the utility installs a bidirectional meter?

Disconnect household loads.
Energise the inverter briefly and watch the old meter; consumed kWh rise if generation flows outward.
Limit the test to minutes to avoid billing surprises [Elektroda, FankyKoval, post #17867337]

What data can the SolarEdge monitoring portal show?

The owner account displays real-time power, energy, voltage and current for each panel, plus historical charts. Installer access adds alerts and remote firmware updates [YouTube tutorial link; Elektroda, krissgut, #17868992].

Why did my 5 kW inverter clip at 5.3 kW despite 6.5 kWp of panels?

Most inverters sustain 110 % overload for minutes, then clip to rated 5 kW. Panel oversizing still boosts winter and cloudy-day yield by 5–10 % [Elektroda, Anonymous, post #18110640]

Edge-case: what if one optimizer fails?

A failed optimizer isolates only its panel; the rest of the string operates normally. Replacement takes <10 minutes but requires rooftop access [SolarEdge Service Manual 2023].

Three steps to size string voltage correctly

Multiply panel Voc at –10 °C by panel count.
Verify result ≤ inverter’s absolute max DC voltage.
Ensure MPP voltage stays above start-up level at midsummer heat [Elektroda, Wojtek_375, post #17852346]

Can I upgrade from a 5 kW to a 10 kW inverter later?

Yes, provided AC cabling and main breaker handle 16 A per phase. Plan conduit size and roof DC wiring for future 10 kW to avoid re-installation cost [Elektroda, Anonymous, post #18111719]