A solar and battery system for demand cost control

A solar and battery system for demand cost control

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While solar photovoltaic power is well-known, there has been a lot of media coverage given to batteries as “the next biggest thing”. But are there any opportunities here and now for them, particularly in commercial operations? We recently worked with a manufacturing client where they DO check out – both technically and financially.

The client is located in north Queensland with a tariff that has a very high demand cost component. Further, their operations include one very large line that only runs a few hours per day, but constitutes around 60% of their demand and so sets their monthly demand cost. Tackling that peak was the key to reducing their costs.

We took the interval meter data, and modelled the hourly output of a solar PV plant. We also modelled the impact of a battery system, and created a control algorithm aimed at reducing the maximum demand.

We researched four different battery chemistries including lead acid, lithium ion and flow batteries to determine costs, round-trip efficiency, depth of discharge and effective life.

Altogether, we were able to determine the right combination of solar size, battery technology, storage capacity and battery discharge rate to achieve the highest financial return for the customer.

We found that:

  • the combination of solar PV and a battery work very well together
  • the economic case worked due to the short peaky nature of the consumption profile, and the very high demand cost tariff
  • newer battery technologies are indeed supplanting traditional lead-acid batteries, but the right choice is highly dependent on the usage of the battery – consideration of duty cycle and the impact on long-term maintenance is critical

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