Fix formatting JSON export via PVSystem.payload_to_file

CHANGELOG.md

@@ -5,6 +5,34 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Added
+
+- `PVSystem` enum inputs (`mounting`, `module_orientation`, `inverter_type`) accept case-insensitive strings,
+  at construction and on assignment.
+- `PVSystem.with_defaults_applied()` returns a copy with all unset derived inputs resolved.
+
+### Changed
+
+- Derived `PVSystem` inputs (`mounting_height`, ohmic losses, bifacial parameters, transformer losses) are now
+  resolved when the payload is built; they read as `None` until set explicitly. Use `describe()` or
+  `with_defaults_applied()` to see effective values.
+- `PVSystem.payload` is now an output-only snapshot (JSON string) and is no longer read back; it is omitted
+  from `to_file()` output.
+- Building a payload no longer overwrites the plant's `dc_capacity_MW`, `ac_capacity_MW` or `gcr`.
+
+### Fixed
+
+- Payloads built after changing `mounting`, `bifacial`, `inverter_type` or `transformer_stages` now use the
+  corresponding derived defaults. Previously they were silently ignored, e.g. bifacial losses stayed 0
+  after `plant.bifacial = True`; results from workflows that assign these after construction will change.
+- A stale cached payload could be sent after editing a plant (including via `make_copy()`).
+- `PVSystem.set_inverter_from_rcl()` no longer multiplies the inverter efficiency by 100 in the
+  "Narrow your search" message (e.g. `eff=9860.0%` is now `eff=98.6%`).
+- `PVSystem.payload_to_file()` now writes indented JSON instead of a single compact line, and keeps
+  non-ASCII characters (e.g. in module or inverter file names) instead of escaping them as `\uXXXX`.
+
 ## [0.7.0] - 2026-10-07
 
 ### Added
@@ -31,7 +59,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Flush-mount `PVSystem` tilt handling now preserves `plant.tilt` in mounting
 	specifications instead of forcing `0.0`, aligning flush-mount behaviour with
-	user-provided fixed-tilt inputs. 
+	user-provided fixed-tilt inputs.
 
 ## [0.6.0] - 2026-09-24
 

docs/getting-started/workflow-2-pvplant-builder.md

@@ -124,6 +124,15 @@ plant.bifacial_shade_loss = 0.15
 plant.bifacial_mismatch_loss = 0.01
 ```
 
+### Derived defaults
+
+Unset mounting height, inverter and transformer losses, and bifacial parameters are derived when the
+payload is built, using the final values of `mounting`, `bifacial`, `inverter_type` and
+`transformer_stages`. You can assign these inputs in any order. Set an individual derived field to
+override its default; explicit values including `0.0` are preserved. Read effective values with
+`plant.with_defaults_applied()` or `plant.describe(verbose=True)`. Enum strings such as `"tracker"`
+are accepted case-insensitively.
+
 ---
 
 ## Step 3: Add Module and Inverter Files

solarfarmer/models/pvsystem/plant_defaults.py

@@ -10,21 +10,34 @@
 # ------------------------------------------------------------------------------
 
 
-class InverterType(str, Enum):
+class _CaseInsensitiveStrEnum(str, Enum):
+    """String enum whose lookup by value ignores case (e.g. ``"fixed"`` -> ``FIXED``)."""
+
+    @classmethod
+    def _missing_(cls, value):
+        if isinstance(value, str):
+            folded = value.strip().casefold()
+            for member in cls:
+                if member.value.casefold() == folded:
+                    return member
+        return None
+
+
+class InverterType(_CaseInsensitiveStrEnum):
     """Enumeration for inverter types."""
 
     STRING = "String"
     CENTRAL = "Central"
 
 
-class MountingType(str, Enum):
+class MountingType(_CaseInsensitiveStrEnum):
     """Enumeration for mounting types."""
 
     FIXED = "Fixed"
     TRACKER = "Tracker"
 
 
-class OrientationType(str, Enum):
+class OrientationType(_CaseInsensitiveStrEnum):
     """Enumeration for module orientation types."""
 
     PORTRAIT = "Portrait"