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Senad Uka
248
helix/calculators/ballast_calculator.py
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248
helix/calculators/ballast_calculator.py
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from collections import namedtuple, OrderedDict
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from math import ceil, floor
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from helix.constants.panel_type import PanelType
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from helix.constants.system_type import SystemType
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from helix.models.panel import Panel, PanelWarnings
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Result = namedtuple('Result', ['ballast_count', 'link_tray_count', 'cross_tray_count', 'system_weight', 'needs_anchor'])
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class BallastCalculator(object):
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def __init__(self, user_values):
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self.values = user_values
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self.system_type = user_values.system_type()
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self.anchor_type = user_values.anchor_type()
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self.system_constants = self.system_type.system_constants()
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self.module_constants = user_values.module_system_constants()
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def ballast_and_trays_matrix(self, c_p_matrix, q_z, panels, ballast_block_weight=None):
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if not ballast_block_weight:
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ballast_block_weight = self.values.ballast_block_weight()
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ballast_store = self.calculate_ballast_store(c_p_matrix, q_z, ballast_block_weight)
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for idx, panel in enumerate(panels):
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stored_panel = ballast_store[panel.panel_type][panel.wind_zone][panel.fuzzy_wind_zone]
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panels[idx] = stored_panel.merge(panel)
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return panels
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def update_ballast(self, c_p_matrix, q_z, panels):
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ballast_block_weight = self.values.ballast_block_weight()
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ballast_store = self.calculate_ballast_store(c_p_matrix, q_z, ballast_block_weight)
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seismic_ballast_store = {}
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for panel in panels:
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seismic_anchors = panel.seismic_anchors if panel.seismic_anchors else 0
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if seismic_anchors != 0:
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key = hash(panel.wind_zone) + hash(panel.panel_type) + seismic_anchors + hash(panel.fuzzy_wind_zone) # hack
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stored_panel = seismic_ballast_store.get(key)
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if stored_panel:
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panel.ballast = stored_panel.ballast
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panel.link_tray = stored_panel.link_tray
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panel.cross_tray = stored_panel.cross_tray
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panel.pressure = stored_panel.pressure
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else:
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anchors = panel.wind_anchors + seismic_anchors
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c_p = c_p_matrix[panel.wind_zone, panel.panel_type.index()] * (1.15 if panel.fuzzy_wind_zone else 1)
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force = self.uplift(c_p, q_z) - anchors * self.anchor_type.uplift_capacity()
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ballast_and_tray_count = self.ballast_and_tray_count(force, panel.panel_type, ballast_block_weight, anchors)
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pressure = self.calculate_pressure_on_roof(ballast_and_tray_count.ballast_count, ballast_block_weight, ballast_and_tray_count.system_weight)
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panel.ballast = ballast_and_tray_count.ballast_count
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panel.link_tray = ballast_and_tray_count.link_tray_count
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panel.cross_tray = ballast_and_tray_count.cross_tray_count
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panel.pressure = pressure
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seismic_ballast_store[key] = panel
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else:
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stored_panel = ballast_store[panel.panel_type][panel.wind_zone][panel.fuzzy_wind_zone]
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panel.ballast = stored_panel.ballast
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panel.link_tray = stored_panel.link_tray
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panel.cross_tray = stored_panel.cross_tray
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panel.pressure = stored_panel.pressure
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return panels
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def calculate_ballast_store(self, cp_matrix, qz, ballast_block_weight):
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max_psf = self.values.max_system_pressure()
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store = {}
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for panel_type in PanelType.all():
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sub_store = {}
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for wind_zone, _ in enumerate(self.values.system_type().system_constants().wind_zones):
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sub_store[wind_zone] = {}
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for use_fuzzy in (True, False):
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sub_store[wind_zone][use_fuzzy] = self.ballast_tray_and_anchor_count(wind_zone=wind_zone,
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panel_type=panel_type,
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ballast_block_weight=ballast_block_weight,
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max_system_pressure=max_psf,
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c_p_matrix=cp_matrix,
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q_z=qz,
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use_fuzzy=use_fuzzy)
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store[panel_type] = sub_store
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return store
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def summary_table(self, c_p_matrix, q_z):
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wind_zones = self.system_constants.wind_zones
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ballast_block_weight = self.values.ballast_block_weight()
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max_system_pressure = self.values.max_system_pressure()
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table = OrderedDict()
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for panel_type in PanelType.all():
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ballast_counts = []
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anchor_counts = []
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pressures = []
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warnings = []
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for wind_zone_index, _ in enumerate(wind_zones):
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ballast_tray_anchor_panels = self.ballast_tray_and_anchor_count(wind_zone_index, panel_type,
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ballast_block_weight, max_system_pressure,
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c_p_matrix, q_z)
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anchor_count = ballast_tray_anchor_panels.wind_anchors
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ballast_count = ballast_tray_anchor_panels.ballast
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pressure = ballast_tray_anchor_panels.pressure
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warning = ballast_tray_anchor_panels.warnings
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pressure_as_string = "{0:.2f}".format(pressure)
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# Because pressure is stored as a floating point number, it is possible, because floats
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# for pressure to be something like 5.02999999999999. Which is clearly meant to be 5.03.
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# This represents that as a string, which doesn't have that issue.
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anchor_counts.append(anchor_count)
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ballast_counts.append(ballast_count)
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pressures.append(pressure_as_string)
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warnings.append(warning)
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table[panel_type] = {
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'ballast blocks': ballast_counts,
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'anchors': anchor_counts,
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'pressure': pressures,
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'warnings': warnings
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}
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return table
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def ballast_tray_and_anchor_count(self, wind_zone, panel_type, ballast_block_weight, max_system_pressure,
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c_p_matrix, q_z, use_fuzzy=False):
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fuzzy_factor = 1.15 if use_fuzzy else 1
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c_p = c_p_matrix[wind_zone, panel_type.index()] * fuzzy_factor
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uplift_force = self.uplift(c_p, q_z)
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warnings = []
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keep_trying = True
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anchor_count = 0
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pressure = 0.
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tries = 0
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ballast_and_tray_count = None
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while keep_trying:
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remainder_force = uplift_force - anchor_count * self.anchor_type.uplift_capacity()
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ballast_and_tray_count = self.ballast_and_tray_count(remainder_force, panel_type, ballast_block_weight, anchor_count)
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pressure = self.calculate_pressure_on_roof(ballast_and_tray_count.ballast_count, ballast_block_weight, ballast_and_tray_count.system_weight)
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keep_trying = (ballast_and_tray_count.needs_anchor or pressure > max_system_pressure) and ballast_and_tray_count.ballast_count > 0
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if keep_trying:
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anchor_count = self.calculate_anchors(panel_type, uplift_force) + tries
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tries += 1
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keep_trying &= tries < 100
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if uplift_force / self.module_constants.surface_area >= self.module_constants.max_psf:
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warnings.append(PanelWarnings.MaxPsf)
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return Panel(wind_zone=wind_zone,
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panel_type=panel_type,
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ballast=ballast_and_tray_count.ballast_count,
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link_tray=self.interpret_tray_count(ballast_and_tray_count.link_tray_count, panel_type),
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cross_tray=ballast_and_tray_count.cross_tray_count,
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wind_anchors=anchor_count,
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pressure=pressure,
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fuzzy_wind_zone=use_fuzzy,
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warnings=warnings)
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def ballast_and_tray_count(self, force_to_resist, panel_type, ballast_block_weight, anchor_count):
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system_weight = self.module_constants.base_weight(panel_type, 0)
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ballast_count = self.calculate_ballast(force_to_resist, system_weight, ballast_block_weight)
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link_tray_count = 0
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cross_tray_count = 0
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needs_anchor = False
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keep_trying = True
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tries = 0
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while keep_trying and tries < 3:
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tries += 1
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if ballast_count:
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new_link_tray_count, _ = self.calculate_trays(ballast_count + 2 * anchor_count,
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self.module_constants.link_tray_thresholds(panel_type))
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# Recalculate weight given new link trays; recalculate ballast given new weight
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system_weight = self.module_constants.base_weight(panel_type, new_link_tray_count + cross_tray_count)
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ballast_count = self.calculate_ballast(force_to_resist, system_weight, ballast_block_weight)
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new_cross_tray_count, needs_anchor = self.calculate_trays(ballast_count + 2 * anchor_count,
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self.module_constants.cross_tray_thresholds(
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panel_type))
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system_weight = self.module_constants.base_weight(panel_type, new_cross_tray_count + new_link_tray_count)
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ballast_count = self.calculate_ballast(force_to_resist, system_weight, ballast_block_weight)
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if link_tray_count == new_link_tray_count and cross_tray_count == new_cross_tray_count:
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keep_trying = False
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link_tray_count = new_link_tray_count
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cross_tray_count = new_cross_tray_count
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else:
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keep_trying = False
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return Result(ballast_count, link_tray_count=link_tray_count, cross_tray_count=cross_tray_count,
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system_weight=system_weight, needs_anchor=needs_anchor)
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def uplift(self, c_p, q_z):
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return q_z * self.module_constants.surface_area * c_p
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def calculate_ballast(self, uplift, non_ballast_weight, ballast_block_weight):
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if non_ballast_weight > uplift:
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return 0
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return ceil((uplift - non_ballast_weight) / ballast_block_weight)
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def calculate_trays(self, ballast_count, thresholds):
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for idx, threshold in enumerate(thresholds):
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if ballast_count <= threshold:
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return idx, False
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return len(thresholds) - 1, True
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def calculate_pressure_on_roof(self, ballast_count, ballast_block_weight, non_ballast_weight):
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effective_area = self.module_constants.surface_area / self.module_constants.ground_coverage_ratio
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return (ballast_count * ballast_block_weight + non_ballast_weight) / effective_area
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def interpret_tray_count(self, link_tray_count, panel_type):
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if self.system_type == SystemType.singleTilt:
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if panel_type == PanelType.EastWest:
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return 2
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elif panel_type == PanelType.Corner or panel_type == PanelType.NorthSouth:
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return 0
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return link_tray_count or 0
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def calculate_anchors(self, panel_type, uplift):
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base_system_weight = self.module_constants.base_weight(panel_type, 0)
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anchor_capacity = self.anchor_type.uplift_capacity()
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return max(floor((uplift - base_system_weight) / anchor_capacity), 1)
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def show_presented_link_trays(self, panels):
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for panel in panels:
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panel.presented_link_tray = self.present_link_tray(panel.link_tray, panel.panel_type)
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return panels
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def present_link_tray(self, link_tray_count, panel_type):
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if self.system_type == SystemType.singleTilt:
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link_tray_representation = {
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PanelType.Corner: 0,
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PanelType.NorthSouth: 0,
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PanelType.EastWest: 2,
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PanelType.Middle: min(1, int(link_tray_count)),
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}[panel_type]
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else:
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link_tray_representation = {
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PanelType.Corner: 2,
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PanelType.NorthSouth: 2,
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PanelType.EastWest: 1,
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PanelType.Middle: min(1, int(link_tray_count)),
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}[panel_type]
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return link_tray_representation
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