Wells - Beyond the Panels: An Independent Demand & Network Charge Review at Ōwae Marae

Beyond the Panels: An Independent Demand & Network Charge Review at Ōwae Marae

When Ōwae Marae in Waitara installed a 44 kW rooftop solar and battery system in 2023, trustees expected relief from rising power costs. Instead, monthly bills quadrupled from around $500 to $2,000 despite strong solar generation. Rather than assuming the system was faulty, the marae's trustees sought an independent technical review from Wells Instrument & Electrical, delivered through the Community Energy Activator 2025 programme.

Wells engineer Moji Abbasi combined 30 days of interval billing data, inverter monitoring data, and an on-site equipment audit to diagnose the problem. The findings showed the solar array was performing exactly as designed, generating over 5,000 kWh in the review period. But only 24% was used on site; the rest was exported and uncredited. The real driver of costs was the marae's demand-based tariff: short, sharp spikes from kitchen, hot water, and HVAC loads running simultaneously were setting a contracted demand charge that made up roughly 70% of the total bill. Poor phase balance and power factor issues were compounding the problem, while the battery — though functioning — was configured for self-consumption rather than peak-shaving.

Wells recommended a staged approach: manage simultaneous equipment use, reconfigure battery discharge to target demand peaks, address electrical quality issues, and renegotiate tariff and export arrangements with the retailer and network.

The case study is a timely reminder for the wider distributed energy sector: a correctly functioning solar and battery system won't automatically lower costs on a demand-based tariff. Independent, trusted engineering review — not more panels — is often the key to unlocking real savings