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Fix math review findings (#826 Redmine note follows)

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- constants drift: CURRENT_MONTHLY_BILL 301.08->264.47, CURRENT_ANNUAL_CONSUMPTION 23952->22614 (15-month billing table is truth)
- plan header: ROI 9.1 -> 10.2 yrs (matches table); 14% -> 26.6% kWh / 12.7% bill offset
- Dockerfile entrypoint ran DEPRECATED solar_estimate.py (400W panels); now runs the current bash analyzer on alpine
- scenario payback caveat: fixed $4,100 cost across array sizes = optimistic ceilings

https://projects.knownelement.com/issues/826#note-1
This commit is contained in:
mrcharles
2026-09-06 14:02:12 -05:00
parent 2f17f2025b
commit b3effbe044
3 changed files with 16 additions and 10 deletions
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solar-analysis/Dockerfile
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@@ -1,9 +1,13 @@
FROM python:3.11-slim # SITER-Solar analysis container — runs the CURRENT bash analyzer.
# (2026-09-06, #826: entrypoint previously ran the DEPRECATED
# solar_estimate.py, which also assumed 400W panels. Retired.)
FROM alpine:3.20
RUN apk add --no-cache bash curl jq bc
WORKDIR /app WORKDIR /app
RUN pip install --no-cache-dir requests COPY siter-solar-analysis.sh /app/siter-solar-analysis.sh
RUN chmod +x /app/siter-solar-analysis.sh
COPY solar_estimate.py /app/ ENTRYPOINT ["/app/siter-solar-analysis.sh"]
ENTRYPOINT ["python", "solar_estimate.py"]
solar-analysis/siter-solar-analysis.sh
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@@ -49,8 +49,8 @@ readonly DEFAULT_ARRAY_TYPE="0"
# Financial parameters # Financial parameters
readonly PROJECT_COST="4100" readonly PROJECT_COST="4100"
readonly CURRENT_MONTHLY_BILL="301.08" readonly CURRENT_MONTHLY_BILL="264.47" # 15-month avg from v2 plan billing table (was 301.08, stale)
readonly CURRENT_ANNUAL_CONSUMPTION="23952" readonly CURRENT_ANNUAL_CONSUMPTION="22614" # 15-month avg x12 from v2 plan (was 23952, stale)
readonly CONSUMPTION_RATE="0.085" readonly CONSUMPTION_RATE="0.085"
readonly EXPORT_RATE="0.04" readonly EXPORT_RATE="0.04"
readonly SELF_CONSUMPTION_PCT="0.60" readonly SELF_CONSUMPTION_PCT="0.60"
v2-siter-solar-plan.md
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@@ -8,14 +8,14 @@
This document outlines a solar energy installation project for SITER, designed to offset a portion of monthly electricity costs through solar generation. The system will utilize 16 solar panels across 8 custom-built ground-mount racks, paired with a Sol-Ark 5K hybrid inverter that integrates with the existing Base Power battery backup system. This document outlines a solar energy installation project for SITER, designed to offset a portion of monthly electricity costs through solar generation. The system will utilize 16 solar panels across 8 custom-built ground-mount racks, paired with a Sol-Ark 5K hybrid inverter that integrates with the existing Base Power battery backup system.
**Total Project Investment:** $4,100.00 **Total Project Investment:** $4,100.00
**Estimated ROI Period:** 9.1 years (based on updated billing analysis) **Estimated ROI Period:** 10.2 years (baseline 4.0 kW system, updated billing analysis)
**Estimated Monthly Savings:** $37.61 (14.2% bill offset) **Estimated Monthly Savings:** $37.61 (14.2% bill offset)
**Existing Infrastructure:** SITER currently operates with a Base Power battery backup system and automatic transfer switch (ATS), installed in 2025, providing resilience and a fixed energy rate of **$0.085/kWh** through a 3-year contract (Oct 2025 - Oct 2028). **Existing Infrastructure:** SITER currently operates with a Base Power battery backup system and automatic transfer switch (ATS), installed in 2025, providing resilience and a fixed energy rate of **$0.085/kWh** through a 3-year contract (Oct 2025 - Oct 2028).
**Updated Billing Data (15 months):** Average monthly consumption of 1,885 kWh (~22,600 kWh/year) at average effective rate of $0.140/kWh. **Updated Billing Data (15 months):** Average monthly consumption of 1,885 kWh (~22,600 kWh/year) at average effective rate of $0.140/kWh.
**NREL PVWatts Analysis:** Based on location data for SITER, a 16-panel system (4.0 kW DC with 250W panels) is projected to produce ~6,000 kWh/year, offsetting approximately 14% of current consumption. **NREL PVWatts Analysis:** Based on location data for SITER, a 16-panel system (4.0 kW DC with 250W panels) is projected to produce ~6,000 kWh/year, offsetting ~26.6% of current consumption kWh (~12.7% of the bill).
--- ---
@@ -36,7 +36,7 @@ This document outlines a solar energy installation project for SITER, designed t
### Objectives ### Objectives
- Reduce monthly electricity expenses through solar generation (~14% offset with current panels) - Reduce monthly electricity expenses through solar generation (~12.7% bill offset with current panels)
- Integrate with existing Base Power battery backup infrastructure - Integrate with existing Base Power battery backup infrastructure
- Leverage Base Power's 4¢/kWh solar buyback program for excess production - Leverage Base Power's 4¢/kWh solar buyback program for excess production
- Complete installation with minimal upfront capital expenditure - Complete installation with minimal upfront capital expenditure
@@ -370,6 +370,8 @@ The ground-mount configuration at this site has significant advantages:
The site's open exposure and ground-mount flexibility make it an ideal solar location. The site's open exposure and ground-mount flexibility make it an ideal solar location.
> **Cost caveat (2026-09-06 audit, #826):** the scenario payback rows above and in §ROI assume the SAME $4,100 project cost at every array size. Larger arrays need more panels+racking, so the improved paybacks at 4.8–8.0 kW are optimistic ceilings; per-scenario BOM costing is queued.
### Monthly Production Profile (NREL) ### Monthly Production Profile (NREL)
| Month | AC Output (kWh) | Daily Avg | Solar Rad (kWh/m²/day) | | Month | AC Output (kWh) | Daily Avg | Solar Rad (kWh/m²/day) |