diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 15c4ef4..dd12b95 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -9,7 +9,12 @@ repos:
     -   id: check-yaml
     -   id: check-added-large-files
     -   id: flake8
+        args: ['--max-line-length=120']  # default of Black
     -   id: requirements-txt-fixer
     -   id: check-merge-conflict
     -   id: name-tests-test
         args: ['--django']
+- repo: https://github.com/pre-commit/mirrors-isort
+  rev: v4.3.4
+  hooks:
+  - id: isort
diff --git a/onsset/onsset.py b/onsset/onsset.py
index 1622c1a..ae064b8 100644
--- a/onsset/onsset.py
+++ b/onsset/onsset.py
@@ -1,15 +1,12 @@
 import logging
-import pandas as pd
-from math import ceil, pi, exp, log, sqrt, radians, cos, sin, asin
+from math import asin, ceil, cos, exp, log, pi, radians, sin, sqrt
+
 # from pyproj import Proj
 import numpy as np
+import pandas as pd
 
 logging.basicConfig(format='%(asctime)s\t\t%(message)s', level=logging.DEBUG)
 
-# General
-LHV_DIESEL = 9.9445485  # (kWh/l) lower heating value
-HOURS_PER_YEAR = 8760
-
 # Columns in settlements file must match these exactly
 SET_COUNTRY = 'Country'  # This cannot be changed, lots of code will break
 SET_X_DEG = 'X_deg'  # Coordinates in degrees
@@ -100,43 +97,9 @@
 SET_SA_DIESEL_FUEL = 'SADieselFuelCost'
 SET_MG_DIESEL_FUEL = 'MGDieselFuelCost'
 
-# Columns in the specs file must match these exactly
-SPE_COUNTRY = 'Country'
-SPE_POP = 'PopStartYear'  # The actual population in the base year
-SPE_URBAN = 'UrbanRatioStartYear'  # The ratio of urban population (range 0 - 1) in base year
-SPE_POP_FUTURE = 'PopEndYear'
-SPE_URBAN_FUTURE = 'UrbanRatioEndYear'
-SPE_URBAN_MODELLED = 'UrbanRatioModelled'  # The urban ratio in the model after calibration (for comparison)
-SPE_URBAN_CUTOFF = 'UrbanCutOff'  # The urban cutoff population calirated by the model, in people per km2
-SPE_URBAN_GROWTH = 'UrbanGrowth'  # The urban growth rate as a simple multplier (urban pop future / urban pop present)
-SPE_RURAL_GROWTH = 'RuralGrowth'  # Same as for urban
-SPE_NUM_PEOPLE_PER_HH_RURAL = 'NumPeoplePerHHRural'
-SPE_NUM_PEOPLE_PER_HH_URBAN = 'NumPeoplePerHHUrban'
-SPE_DIESEL_PRICE_LOW = 'DieselPriceLow'  # Diesel price in USD/litre
-SPE_DIESEL_PRICE_HIGH = 'DieselPriceHigh'  # Same, with a high forecast var
-SPE_GRID_PRICE = 'GridPrice'  # Grid price of electricity in USD/kWh
-SPE_GRID_CAPACITY_INVESTMENT = 'GridCapacityInvestmentCost'  # grid capacity investments costs from TEMBA USD/kW
-SPE_GRID_LOSSES = 'GridLosses'  # As a ratio (0 - 1)
-SPE_BASE_TO_PEAK = 'BaseToPeak'  # As a ratio (0 - 1)
-SPE_EXISTING_GRID_COST_RATIO = 'ExistingGridCostRatio'
-SPE_MAX_GRID_DIST = 'MaxGridDist'
-SPE_ELEC = 'ElecActual'  # Actual current percentage electrified population (0 - 1)
-SPE_ELEC_MODELLED = 'ElecModelled'  # The modelled version after calibration (for comparison)
-SPE_ELEC_URBAN = 'Urban_elec_ratio'  # Actual electrification for urban areas
-SPE_ELEC_RURAL = 'Rural_elec_ratio'  # Actual electrification for rural areas
-SPE_MIN_NIGHT_LIGHTS = 'MinNightLights'
-SPE_MAX_GRID_EXTENSION_DIST = 'MaxGridExtensionDist'
-SPE_MAX_ROAD_DIST = 'MaxRoadDist'
-SPE_POP_CUTOFF1 = 'PopCutOffRoundOne'
-SPE_POP_CUTOFF2 = 'PopCutOffRoundTwo'
-SPE_ELEC_LIMIT = "ElecLimit"
-SPE_INVEST_LIMIT = "InvestmentLimit"
-SPE_DIST_TO_TRANS = "DistToTrans"
-
-SPE_START_YEAR = "StartYear"
-SPE_END_YEAR = "EndYEar"
-SPE_TIMESTEP = "TimeStep"
-
+# General
+LHV_DIESEL = 9.9445485  # (kWh/l) lower heating value
+HOURS_PER_YEAR = 8760
 
 class Technology:
     """
diff --git a/onsset/runner.py b/onsset/runner.py
index 987d42a..c0de752 100644
--- a/onsset/runner.py
+++ b/onsset/runner.py
@@ -1,10 +1,23 @@
 # Defines the modules
 
+import logging
 import os
-from onsset import *
+
 import pandas as pd
+from onsset import (SET_ELEC_ORDER, SET_LCOE_GRID, SET_MIN_GRID_DIST,
+                    SET_MV_CONNECT_DIST, SettlementProcessor, Technology)
+from onsset.specs import (SPE_COUNTRY, SPE_ELEC, SPE_ELEC_MODELLED,
+                          SPE_ELEC_RURAL, SPE_ELEC_URBAN, SPE_END_YEAR,
+                          SPE_EXISTING_GRID_COST_RATIO,
+                          SPE_GRID_CAPACITY_INVESTMENT, SPE_GRID_LOSSES,
+                          SPE_MAX_GRID_EXTENSION_DIST,
+                          SPE_NUM_PEOPLE_PER_HH_RURAL,
+                          SPE_NUM_PEOPLE_PER_HH_URBAN, SPE_POP, SPE_POP_FUTURE,
+                          SPE_START_YEAR, SPE_URBAN, SPE_URBAN_FUTURE,
+                          SPE_URBAN_MODELLED)
 from openpyxl import load_workbook
 
+
 def calibration(specs_path, csv_path, specs_path_calib, calibrated_csv_path):
 
 
diff --git a/onsset/specs.py b/onsset/specs.py
new file mode 100644
index 0000000..9fbed25
--- /dev/null
+++ b/onsset/specs.py
@@ -0,0 +1,37 @@
+"""Columns in the specs file must match these exactly
+"""
+SPE_COUNTRY = 'Country'
+SPE_POP = 'PopStartYear'  # The actual population in the base year
+SPE_URBAN = 'UrbanRatioStartYear'  # The ratio of urban population (range 0 - 1) in base year
+SPE_POP_FUTURE = 'PopEndYear'
+SPE_URBAN_FUTURE = 'UrbanRatioEndYear'
+SPE_URBAN_MODELLED = 'UrbanRatioModelled'  # The urban ratio in the model after calibration (for comparison)
+SPE_URBAN_CUTOFF = 'UrbanCutOff'  # The urban cutoff population calirated by the model, in people per km2
+SPE_URBAN_GROWTH = 'UrbanGrowth'  # The urban growth rate as a simple multplier (urban pop future / urban pop present)
+SPE_RURAL_GROWTH = 'RuralGrowth'  # Same as for urban
+SPE_NUM_PEOPLE_PER_HH_RURAL = 'NumPeoplePerHHRural'
+SPE_NUM_PEOPLE_PER_HH_URBAN = 'NumPeoplePerHHUrban'
+SPE_DIESEL_PRICE_LOW = 'DieselPriceLow'  # Diesel price in USD/litre
+SPE_DIESEL_PRICE_HIGH = 'DieselPriceHigh'  # Same, with a high forecast var
+SPE_GRID_PRICE = 'GridPrice'  # Grid price of electricity in USD/kWh
+SPE_GRID_CAPACITY_INVESTMENT = 'GridCapacityInvestmentCost'  # grid capacity investments costs from TEMBA USD/kW
+SPE_GRID_LOSSES = 'GridLosses'  # As a ratio (0 - 1)
+SPE_BASE_TO_PEAK = 'BaseToPeak'  # As a ratio (0 - 1)
+SPE_EXISTING_GRID_COST_RATIO = 'ExistingGridCostRatio'
+SPE_MAX_GRID_DIST = 'MaxGridDist'
+SPE_ELEC = 'ElecActual'  # Actual current percentage electrified population (0 - 1)
+SPE_ELEC_MODELLED = 'ElecModelled'  # The modelled version after calibration (for comparison)
+SPE_ELEC_URBAN = 'Urban_elec_ratio'  # Actual electrification for urban areas
+SPE_ELEC_RURAL = 'Rural_elec_ratio'  # Actual electrification for rural areas
+SPE_MIN_NIGHT_LIGHTS = 'MinNightLights'
+SPE_MAX_GRID_EXTENSION_DIST = 'MaxGridExtensionDist'
+SPE_MAX_ROAD_DIST = 'MaxRoadDist'
+SPE_POP_CUTOFF1 = 'PopCutOffRoundOne'
+SPE_POP_CUTOFF2 = 'PopCutOffRoundTwo'
+SPE_ELEC_LIMIT = "ElecLimit"
+SPE_INVEST_LIMIT = "InvestmentLimit"
+SPE_DIST_TO_TRANS = "DistToTrans"
+
+SPE_START_YEAR = "StartYear"
+SPE_END_YEAR = "EndYEar"
+SPE_TIMESTEP = "TimeStep"