Predictika · PV inverter array and connection design validator, modeled on the SMA Sunny Tripower X

A solar installer's array and connection quote, checked before it is released

A quoting agent for a solar installer prepares a quote for a commercial rooftop array on a Sunny Tripower X inverter: the modules per string, the strings on each input, the grid connection, the protection and the cables. Before the quote is released, the agent sends it to Predictika's validator, which checks the design against the inverter's published limits and reports every problem it finds in one pass.

Scope: PV array and connection quotes for the SMA Sunny Tripower X 12-50, 15-50, 20-50 and 25-50 inverters: strings, voltage, current, array size, grid, protection, cables and the stated figures. No prices are modeled. See everything this validator covers

This validator checks any array design for the modeled inverters, not just the scenarios shown below.

  • Strings and input limits — strings per MPP input, string voltage on the coldest and hottest days, input current and the array size against the model.
  • Power at low voltage — a string whose MPP voltage is below the range for rated power needs a person to accept the lower output.
  • Grid and protection — the permitted grid types, three-phase connection, the residual-current device and its type and rating.
  • Cables and modules — AC, grounding and DC conductor sizes, module protection class, grounding of the array and coupling capacity.
  • Stated figures — the array power and cold string voltage the quote states against the ones the modules give.

Any array design for these inverters that touches these rules is in scope, not only the scenarios pictured here. Not checked: prices, energy yield, shading, mounting and the accuracy of the module data the caller states.

The quoting agent for Bayline SolarPrepares the array and connection quote for a customer of a fictional installer and asks to release it.
Predictika validatorChecks every rule at once and returns the verdict, each finding, and the computed figures.

7 scenarios in 3 groups · each group runs from the agent’s first attempt to the outcome · click one to switch

What the agent proposes

The quoting agent for Bayline Solar says

Illustrative agent statement. The validator receives the structured request below.

Proposing agent: quoting agent for Bayline Solar (scripted)

Before sending, the agent must call Recorded run

Predictika validator


      

        
        
        
      

      
Waiting for the call.

      
    

  

  
  

    
Where a catalog compatibility check gets this wrong
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Our assessment of what a typical catalog compatibility check (a module and an inverter that are listed as a pair, each limit checked on its own) does with the same cases. It is a judgment about effort and reliability, not a claim that nothing can be built.

    
What the validator caughtA catalog compatibility checkPredictika
Limits that depend on the string lengthOnly with workarounds
The cold string voltage is the number of modules times the module voltage on the coldest day, and the MPP voltage and the hottest-day voltage need the same multiplication with other module figures.		The voltages are computed from the modules per string inside the model, and every limit is checked in the same pass.
Currents that depend on how the strings are spreadOnly with care
The current on an input depends on how many strings sit on it, so the same total number of strings can pass or fail.		The strings on each input are in one request and the busiest input is checked on every call.
Stated figures reconciled with the computed onesOnly with workarounds
The array power and cold voltage on the quote have to be compared with figures that come from the strings and modules.		The figures are computed inside the model and compared with the stated ones on every call.
Installation rules that sit apart from the arrayOnly with care
The grid type, the phases, the residual-current device and the cable sizes are separate conditions that a pairing check does not look at.		Each is a finding of its own and all are returned together.
Every problem returned in one answerOnly with workarounds
Form checks usually stop at the first failing field, so an agent fixes one error and meets the next.		All findings come back together, whatever order the choices arrived in.

  

  

    
What this validator catches: findings from its test cases
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Every rule is checked on every call, in any order the choices arrive; one problem never hides another. Blocking findings stop the quote; approval findings need a person to sign off; everything else is computed.

    
1Each MPP input takes two strings at most, and the current on the busiest input must stay within the maximum usable and short-circuit currents.
2The cold string voltage must not exceed 1,000 V, the string voltage on the hottest day must stay above the minimum, and a string outside the MPP voltage range for rated power needs a person to accept the lower output.
3The PV array must not exceed the maximum power of the model, and the array power and cold string voltage stated on the quote must match what the modules add up to.
4The grid must be TN-C, TN-S, TN-C-S or TT, and the connection must be three-phase.
5A residual-current device, if required, must be type A or B rated 100 mA or more, one per inverter.
6The AC line and neutral, the grounding conductor and the DC cable must be within their allowed cross-sections.
7The PV modules must be protection class II with outputs not grounded, and their coupling capacity to ground must not exceed 6 microfarads.

  

  

    
Scenarios and results
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The recorded result of the validator for each scenario on this page: the request the AI agent sent, the verdict, and every finding, in the order they appear above.

    
1. A large array with several design faults: Large array with three strings on one input, long strings and a wrong stated power

    
The agent's request. Quote for Brightwater Dairy: one Sunny Tripower X 25-50 with five strings of 20 modules, 450 W each, three strings on input A and one each on inputs B and C. The modules have 51 V open-circuit voltage on the coldest day. The array is 30,000 Wp and the cold string voltage is 1,020 V. The connection has a type AC residual-current device of 30 mA and an 8 mm2 DC cable. Please validate the quote so I can release it.

    
Verdict: Blocked.

    
    
      
  • Too many strings on one input. Each MPP input of the Sunny Tripower X takes 2 strings at most; the quote puts 3 strings on one input.
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  • String voltage too high on the coldest day. The open-circuit voltage of a string on the coldest day is 1,020 V, above the 1,000 V maximum input voltage; the inverter can be destroyed.
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  • Input current above the maximum. The busiest MPP input carries 33.0 A of MPP current, above the 24 A maximum usable input current.
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  • Array larger than this model allows. The PV array is 45,000 Wp, above the maximum PV array power of 37,500 Wp for this model.
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  • Stated array power does not match the modules. The quote states a 30,000 Wp array, but the strings and modules on it add up to 45,000 Wp.
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  • Residual-current device not acceptable. If a residual-current device is required it must be type A or B with a rated residual current of 100 mA or more; the quote has a 30 mA device.
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  • DC cable size out of range. The DC cable conductor cross-section must be 2.5 to 6 mm2; the quote has 8.0 mm2.
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  • Voltage below the range for rated power. The string MPP voltage of 820 V is outside the MPP voltage range for rated power of this model, so the inverter cannot deliver its rated power; a person must accept the lower output.
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2. A large array with several design faults: The agent resubmits after fixing the errors

    
The agent's request. Revised quote for Brightwater Dairy: one Sunny Tripower X 25-50 with five strings of 10 modules, 450 W each, two strings on inputs A and B and one on input C. The modules have 51 V open-circuit voltage on the coldest day. The array is 22,500 Wp and the cold string voltage is 510 V. The connection has a type B residual-current device of 100 mA and a 4 mm2 DC cable. Please validate the quote so I can release it.

    
Verdict: Needs approval.

    
    
      
  • Voltage below the range for rated power. The string MPP voltage of 410 V is outside the MPP voltage range for rated power of this model, so the inverter cannot deliver its rated power; a person must accept the lower output.
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  • Array summary. The array is 22,500 Wp on 5 strings; cold string voltage 510 V and MPP string voltage 410 V.
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3. A large array with several design faults: The agent resubmits after fixing the errors

    
The agent's request. Revised quote for Brightwater Dairy: the same inverter and layout with 11 modules per string. The array is 24,750 Wp and the cold string voltage is 561 V. Please validate the quote so I can release it.

    
Verdict: Allowed.

    
    
      
  • Array summary. The array is 24,750 Wp on 5 strings; cold string voltage 561 V and MPP string voltage 451 V.
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4. A winery connection that breaks the installation rules: Winery connection on an IT grid with a single-phase feed and undersized conductors

    
The agent's request. Quote for Cedar Ridge Winery: one Sunny Tripower X 15-50 with three strings of 16 modules, 450 W each, one string on each input. The array is 21,600 Wp and the cold string voltage is 816 V. The site has an IT grid with a single-phase connection, 4 mm2 AC line and neutral conductors, a 6 mm2 grounding conductor with no additional grounding, protection class I modules and a module coupling capacity of 8 microfarads. Please validate the quote so I can release it.

    
Verdict: Blocked.

    
    
      
  • Grid type not permitted. Operation in IT or Delta IT grids is not permitted; the inverter is approved for TN-C, TN-S, TN-C-S and TT grids.
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  • Single-phase connection not possible. The Sunny Tripower X feeds in three phases; a single-phase connection is not possible.
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  • AC line conductor size out of range. The AC line and neutral conductors must be 6 to 16 mm2 copper; the quote has 4 mm2.
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  • Grounding conductor size out of range. The grounding conductor must be 6 to 16 mm2, and at least 10 mm2 unless additional grounding is connected; the quote has 6 mm2.
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  • Module protection class not accepted. The inverter may only be operated with PV modules of protection class II in accordance with IEC 61730, application class A.
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  • Module coupling capacity too high. The coupling capacity of all PV modules to ground must not exceed 6 uF; the quote has 8.0 uF.
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5. A winery connection that breaks the installation rules: The agent resubmits after fixing the errors

    
The agent's request. Revised quote for Cedar Ridge Winery: the same inverter and array on a TN-S three-phase grid, with 10 mm2 AC line and neutral conductors, a 10 mm2 grounding conductor with additional grounding connected, protection class II modules and a module coupling capacity of 1 microfarad. Please validate the quote so I can release it.

    
Verdict: Allowed.

    
    
      
  • Array summary. The array is 21,600 Wp on 3 strings; cold string voltage 816 V and MPP string voltage 656 V.
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6. Strings too long for the coldest day: Strings too long for the coldest day

    
The agent's request. Quote for Alder Creek Cold Storage: one Sunny Tripower X 20-50 with three strings of 20 modules, 450 W each, 51 V open-circuit voltage per module. The array is 27,000 Wp and the cold string voltage is 1,000 V. Please validate the quote so I can release it.

    
Verdict: Blocked.

    
    
      
  • String voltage too high on the coldest day. The open-circuit voltage of a string on the coldest day is 1,020 V, above the 1,000 V maximum input voltage; the inverter can be destroyed.
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  • Stated string voltage does not match the modules. The quote states a cold string voltage of 1,000 V, but the modules per string give 1,020 V.
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7. Strings too long for the coldest day: The agent resubmits after fixing the errors

    
The agent's request. Revised quote for Alder Creek Cold Storage: one Sunny Tripower X 20-50 with three strings of 19 modules, 450 W each, 51 V open-circuit voltage per module. The array is 25,650 Wp and the cold string voltage is 969 V. Please validate the quote so I can release it.

    
Verdict: Allowed.

    
    
      
  • Array summary. The array is 25,650 Wp on 3 strings; cold string voltage 969 V and MPP string voltage 722 V.
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Narration transcript
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The text of the narrated walkthrough, step by step.

    
    
      
  1. Welcome to a demo of Predictika's Validator. A quoting agent for a solar installer prepares a quote for a commercial rooftop array on a Sunny Tripower X inverter: the modules per string, the strings on each input, the grid connection, and more. Before the quote is released, the agent sends it to Predictika's validator, which checks the design against the inverter's published limits and reports every problem it finds in one pass.
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  2. I will start with the first request by the agent.
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  3. The agent says. Quote for Brightwater Dairy: one Sunny Tripower X 25-50 with five strings of 20 modules, 450 W each, three strings on input A and one each on inputs B and C. The modules have 51 V open-circuit voltage on the coldest day. The rest of the request is on screen. The array is 30,000 Wp and the cold string voltage is 1,020 V.
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  4. Before it goes out, the agent calls the validator.
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  5. Blocked, with seven findings and one approval, all in one answer. Each MPP input of the Sunny Tripower X takes 2 strings at most; the quote puts 3 strings on one input. The open-circuit voltage of a string on the coldest day is 1,020 V, above the 1,000 V maximum input voltage; the inverter can be destroyed. The busiest MPP input carries 33.0 A of MPP current, above the 24 A maximum usable input current. The other four are on screen.
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  6. The validator returned seven blocking findings and one approval in one answer. A check that reads one field at a time would pass most of this; it shows only when the choices in the quote are checked against each other.
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  7. What this shows: for currents that depend on how the strings are spread, a catalog compatibility check is error-prone for this.
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  8. Now the agent resubmits.
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  9. The corrected request. It changes the strings to 2, 2, 1, the modules per string to 10, the residual-current device to Type B, 100 mA, the DC cable to 4, the array power stated on the quote to 22,500 and the cold string voltage stated on the quote to 510.
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  10. It calls the validator again.
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  11. Not blocked, but held for a person.
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  12. The seven blocking findings are cleared; one approval remains for a person: voltage below the range for rated power.
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  13. The agent resubmits once more.
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  14. The revised request. It changes the modules per string to 11, the array power stated on the quote to 24,750 and the cold string voltage stated on the quote to 561.
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  15. It calls the validator once more.
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  16. This time the validator clears it.
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  17. The earlier finding is cleared.
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  18. Eight problems caught in one call, fixed in two passes, and a clean quote. That is the value of Predictika's validator: catching mistakes before they reach the customer. Now you can try the other scenarios yourself.
    19.