Feature: Implement DPL 'overscaling' to compensate shading (#956)

Author: AndreasBoehm

include/Configuration.h

@@ -210,6 +210,7 @@ struct CONFIG_T {
         uint32_t Interval;
         bool IsInverterBehindPowerMeter;
         bool IsInverterSolarPowered;
+        bool UseOverscalingToCompensateShading;
         uint64_t InverterId;
         uint8_t InverterChannelId;
         int32_t TargetPowerConsumption;

include/defaults.h

@@ -127,6 +127,7 @@
 #define POWERLIMITER_INTERVAL 10
 #define POWERLIMITER_IS_INVERTER_BEHIND_POWER_METER true
 #define POWERLIMITER_IS_INVERTER_SOLAR_POWERED false
+#define POWERLIMITER_USE_OVERSCALING_TO_COMPENSATE_SHADING false
 #define POWERLIMITER_INVERTER_ID 0ULL
 #define POWERLIMITER_INVERTER_CHANNEL_ID 0
 #define POWERLIMITER_TARGET_POWER_CONSUMPTION 0

src/Configuration.cpp

@@ -184,6 +184,7 @@ bool ConfigurationClass::write()
     powerlimiter["interval"] = config.PowerLimiter.Interval;
     powerlimiter["is_inverter_behind_powermeter"] = config.PowerLimiter.IsInverterBehindPowerMeter;
     powerlimiter["is_inverter_solar_powered"] = config.PowerLimiter.IsInverterSolarPowered;
+    powerlimiter["use_overscaling_to_compensate_shading"] = config.PowerLimiter.UseOverscalingToCompensateShading;
     powerlimiter["inverter_id"] = config.PowerLimiter.InverterId;
     powerlimiter["inverter_channel_id"] = config.PowerLimiter.InverterChannelId;
     powerlimiter["target_power_consumption"] = config.PowerLimiter.TargetPowerConsumption;
@@ -444,6 +445,7 @@ bool ConfigurationClass::read()
     config.PowerLimiter.Interval =  powerlimiter["interval"] | POWERLIMITER_INTERVAL;
     config.PowerLimiter.IsInverterBehindPowerMeter = powerlimiter["is_inverter_behind_powermeter"] | POWERLIMITER_IS_INVERTER_BEHIND_POWER_METER;
     config.PowerLimiter.IsInverterSolarPowered = powerlimiter["is_inverter_solar_powered"] | POWERLIMITER_IS_INVERTER_SOLAR_POWERED;
+    config.PowerLimiter.UseOverscalingToCompensateShading = powerlimiter["use_overscaling_to_compensate_shading"] | POWERLIMITER_USE_OVERSCALING_TO_COMPENSATE_SHADING;
     config.PowerLimiter.InverterId = powerlimiter["inverter_id"] | POWERLIMITER_INVERTER_ID;
     config.PowerLimiter.InverterChannelId = powerlimiter["inverter_channel_id"] | POWERLIMITER_INVERTER_CHANNEL_ID;
     config.PowerLimiter.TargetPowerConsumption = powerlimiter["target_power_consumption"] | POWERLIMITER_TARGET_POWER_CONSUMPTION;

src/PowerLimiter.cpp

@@ -20,8 +20,8 @@
 
 PowerLimiterClass PowerLimiter;
 
-void PowerLimiterClass::init(Scheduler& scheduler) 
-{ 
+void PowerLimiterClass::init(Scheduler& scheduler)
+{
     scheduler.addTask(_loopTask);
     _loopTask.setCallback(std::bind(&PowerLimiterClass::loop, this));
     _loopTask.setIterations(TASK_FOREVER);
@@ -337,6 +337,16 @@ float PowerLimiterClass::getBatteryVoltage(bool log) {
     return res;
 }
 
+static float getInverterEfficiency(std::shared_ptr<InverterAbstract> inverter)
+{
+    float inverterEfficiencyPercent = inverter->Statistics()->getChannelFieldValue(
+        TYPE_INV, CH0, FLD_EFF);
+
+    // fall back to hoymiles peak efficiency as per datasheet if inverter
+    // is currently not producing (efficiency is zero in that case)
+    return  (inverterEfficiencyPercent > 0) ? inverterEfficiencyPercent/100 : 0.967;
+}
+
 /**
  * calculate the AC output power (limit) to set, such that the inverter uses
  * the given power on its DC side, i.e., adjust the power for the inverter's
@@ -346,12 +356,7 @@ int32_t PowerLimiterClass::inverterPowerDcToAc(std::shared_ptr<InverterAbstract>
 {
     CONFIG_T& config = Configuration.get();
 
-    float inverterEfficiencyPercent = inverter->Statistics()->getChannelFieldValue(
-        TYPE_INV, CH0, FLD_EFF);
-
-    // fall back to hoymiles peak efficiency as per datasheet if inverter
-    // is currently not producing (efficiency is zero in that case)
-    float inverterEfficiencyFactor = (inverterEfficiencyPercent > 0) ? inverterEfficiencyPercent/100 : 0.967;
+    float inverterEfficiencyFactor = getInverterEfficiency(inverter);
 
     // account for losses between solar charger and inverter (cables, junctions...)
     float lossesFactor = 1.00 - static_cast<float>(config.PowerLimiter.SolarPassThroughLosses)/100;
@@ -687,8 +692,7 @@ bool PowerLimiterClass::updateInverter()
  *
  * TODO(schlimmchen): the current implementation is broken and is in need of
  * refactoring. currently it only works for inverters that provide one MPPT for
- * each input. it also does not work as expected if any input produces *some*
- * energy, but is limited by its respective solar input.
+ * each input.
  */
 static int32_t scalePowerLimit(std::shared_ptr<InverterAbstract> inverter, int32_t newLimit, int32_t currentLimitWatts)
 {
@@ -713,6 +717,54 @@ static int32_t scalePowerLimit(std::shared_ptr<InverterAbstract> inverter, int32
     // producing very little due to the very low limit.
     if (currentLimitWatts < dcTotalChnls * 10) { return newLimit; }
 
+    auto const& config = Configuration.get();
+    auto allowOverscaling = config.PowerLimiter.UseOverscalingToCompensateShading;
+    auto isInverterSolarPowered = config.PowerLimiter.IsInverterSolarPowered;
+
+    // overscalling allows us to compensate for shaded panels by increasing the
+    // total power limit, if the inverter is solar powered.
+    if (allowOverscaling && isInverterSolarPowered) {
+        auto inverterOutputAC = inverter->Statistics()->getChannelFieldValue(TYPE_AC, CH0, FLD_PAC);
+        float inverterEfficiencyFactor = getInverterEfficiency(inverter);
+
+        // 98% of the expected power is good enough
+        auto expectedAcPowerPerChannel = (currentLimitWatts / dcTotalChnls) * 0.98;
+
+        size_t dcShadedChnls = 0;
+        auto shadedChannelACPowerSum = 0.0;
+
+        for (auto& c : dcChnls) {
+            auto channelPowerAC = inverter->Statistics()->getChannelFieldValue(TYPE_DC, c, FLD_PDC) * inverterEfficiencyFactor;
+
+            if (channelPowerAC < expectedAcPowerPerChannel) {
+                dcShadedChnls++;
+                shadedChannelACPowerSum += channelPowerAC;
+            }
+        }
+
+        // no shading or the shaded channels provide more power than what
+        // we currently need.
+        if (dcShadedChnls == 0 || shadedChannelACPowerSum >= newLimit) { return newLimit; }
+
+        // keep the currentLimit when all channels are shaded and we get the
+        // expected AC power or less.
+        if (dcShadedChnls == dcTotalChnls && inverterOutputAC <= newLimit) {
+            MessageOutput.printf("[DPL::scalePowerLimit] all channels are shaded, "
+                "keeping the current limit of %d W\r\n", currentLimitWatts);
+
+            return currentLimitWatts;
+        }
+
+        size_t dcNonShadedChnls = dcTotalChnls - dcShadedChnls;
+        auto overScaledLimit = static_cast<int32_t>((newLimit - shadedChannelACPowerSum) / dcNonShadedChnls * dcTotalChnls);
+
+        if (overScaledLimit <= newLimit) { return newLimit; }
+
+        MessageOutput.printf("[DPL::scalePowerLimit] %d/%d channels are shaded, "
+                "scaling %d W\r\n", dcShadedChnls, dcTotalChnls, overScaledLimit);
+        return overScaledLimit;
+    }
+
     size_t dcProdChnls = 0;
     for (auto& c : dcChnls) {
         if (inverter->Statistics()->getChannelFieldValue(TYPE_DC, c, FLD_PDC) > 2.0) {

src/WebApi_powerlimiter.cpp

@@ -38,6 +38,7 @@ void WebApiPowerLimiterClass::onStatus(AsyncWebServerRequest* request)
     root["battery_always_use_at_night"] = config.PowerLimiter.BatteryAlwaysUseAtNight;
     root["is_inverter_behind_powermeter"] = config.PowerLimiter.IsInverterBehindPowerMeter;
     root["is_inverter_solar_powered"] = config.PowerLimiter.IsInverterSolarPowered;
+    root["use_overscaling_to_compensate_shading"] = config.PowerLimiter.UseOverscalingToCompensateShading;
     root["inverter_serial"] = String(config.PowerLimiter.InverterId);
     root["inverter_channel_id"] = config.PowerLimiter.InverterChannelId;
     root["target_power_consumption"] = config.PowerLimiter.TargetPowerConsumption;
@@ -159,6 +160,7 @@ void WebApiPowerLimiterClass::onAdminPost(AsyncWebServerRequest* request)
 
     config.PowerLimiter.IsInverterBehindPowerMeter = root["is_inverter_behind_powermeter"].as<bool>();
     config.PowerLimiter.IsInverterSolarPowered = root["is_inverter_solar_powered"].as<bool>();
+    config.PowerLimiter.UseOverscalingToCompensateShading = root["use_overscaling_to_compensate_shading"].as<bool>();
     config.PowerLimiter.InverterId = root["inverter_serial"].as<uint64_t>();
     config.PowerLimiter.InverterChannelId = root["inverter_channel_id"].as<uint8_t>();
     config.PowerLimiter.TargetPowerConsumption = root["target_power_consumption"].as<int32_t>();

webapp/src/locales/de.json

@@ -637,6 +637,8 @@
         "InverterIsBehindPowerMeter": "Stromzählermessung beinhaltet Wechselrichter",
         "InverterIsBehindPowerMeterHint": "Aktivieren falls sich der Stromzähler-Messwert um die Ausgangsleistung des Wechselrichters verringert, wenn dieser Strom produziert. Normalerweise ist das zutreffend.",
         "InverterIsSolarPowered": "Wechselrichter wird von Solarmodulen gespeist",
+        "UseOverscalingToCompensateShading": "Verschattung durch Überskalierung ausgleichen",
+        "UseOverscalingToCompensateShadingHint": "Erlaubt das Überskalieren des Wechselrichter-Limits, um Verschattung eines oder mehrerer Eingänge auszugleichen",
         "VoltageThresholds": "Batterie Spannungs-Schwellwerte ",
         "VoltageLoadCorrectionInfo": "<b>Hinweis:</b> Wenn Leistung von der Batterie abgegeben wird, bricht ihre Spannung etwas ein. Der Spannungseinbruch skaliert mit dem Entladestrom. Damit nicht vorzeitig der Wechselrichter ausgeschaltet wird sobald der Stop-Schwellenwert unterschritten wurde, wird der hier angegebene Korrekturfaktor mit einberechnet um die Spannung zu errechnen die der Akku in Ruhe hätte. Korrigierte Spannung = DC Spannung + (Aktuelle Leistung (W) * Korrekturfaktor).",
         "InverterRestartHour": "Uhrzeit für geplanten Neustart",

webapp/src/locales/en.json

@@ -643,6 +643,8 @@
         "InverterIsBehindPowerMeter": "PowerMeter reading includes inverter output",
         "InverterIsBehindPowerMeterHint": "Enable this option if the power meter reading is reduced by the inverter's output when it produces power. This is typically true.",
         "InverterIsSolarPowered": "Inverter is powered by solar modules",
+        "UseOverscalingToCompensateShading": "Compensate for shading",
+        "UseOverscalingToCompensateShadingHint": "Allow to overscale the inverter limit to compensate for shading of one or multiple inputs",
         "VoltageThresholds": "Battery Voltage Thresholds",
         "VoltageLoadCorrectionInfo": "<b>Hint:</b> When the battery is discharged, its voltage drops. The voltage drop scales with the discharge current. In order to not stop the inverter too early (stop threshold), this load correction factor can be specified to calculate the battery voltage if it was idle. Corrected voltage = DC Voltage + (Current power * correction factor).",
         "InverterRestartHour": "Automatic Restart Time",

webapp/src/types/PowerLimiterConfig.ts

@@ -26,6 +26,7 @@ export interface PowerLimiterConfig {
     battery_always_use_at_night: boolean;
     is_inverter_behind_powermeter: boolean;
     is_inverter_solar_powered: boolean;
+    use_overscaling_to_compensate_shading: boolean;
     inverter_serial: string;
     inverter_channel_id: number;
     target_power_consumption: number;

webapp/src/views/PowerLimiterAdminView.vue

@@ -68,6 +68,12 @@
                               v-model="powerLimiterConfigList.is_inverter_solar_powered"
                               type="checkbox" wide/>
 
+                <InputElement v-show="canUseOverscaling()"
+                              :label="$t('powerlimiteradmin.UseOverscalingToCompensateShading')"
+                              :tooltip="$t('powerlimiteradmin.UseOverscalingToCompensateShadingHint')"
+                              v-model="powerLimiterConfigList.use_overscaling_to_compensate_shading"
+                              type="checkbox" wide/>
+
                 <div class="row mb-3" v-if="needsChannelSelection()">
                     <label for="inverter_channel" class="col-sm-4 col-form-label">
                         {{ $t('powerlimiteradmin.InverterChannelId') }}
@@ -309,6 +315,10 @@ export default defineComponent({
         hasPowerMeter() {
             return this.powerLimiterMetaData.power_meter_enabled;
         },
+        canUseOverscaling() {
+            const cfg = this.powerLimiterConfigList;
+            return cfg.is_inverter_solar_powered;
+        },
         canUseSolarPassthrough() {
             const cfg = this.powerLimiterConfigList;
             const meta = this.powerLimiterMetaData;