Engineers need average kW per interval, not a generator or coal plant nameplate. Aim for 12 months of timestamped 15–60 minute data: kWh, kW, grid/generator status, production schedules and critical loads. kW × 1 hour = kWh; a 15-minute interval uses 0.25 hours. Separate facility consumption from gross generation, generating auxiliaries and distribution losses.

This example uses 8,760 synthetic hours: 1.2 MW daytime and 0.8 MW night-time demand, with ±8% seasonal variation; annual consumption is 8.760 GWh. It represents no named plantation, excludes any palm-oil mill biomass generation and does not use measured local weather.

SUN-MG-SCREEN-1.0 tests 525 combinations: PV 0–6 MWp in 0.25 MWp steps and BESS 0–10 MWh in 0.5 MWh steps. Each runs through 8,760 hours. PV serves demand first; surplus charges the battery; stored energy serves a deficit; PLN supplies the remainder. Unused surplus is curtailed. Export and export income are zero.

BESS limits: 20–90% SOC, charge and discharge efficiency each √85%, PCS power = 0.4 × nameplate kWh (5 MWh → 2 MW). There is no grid charging, simultaneous charging/discharging, demand charge, time-of-use tariff, ancillary-service revenue or outage event. The result is the lowest cost on the tested size grid and dispatch policy, not a global optimum or bankable design.

Pre-loss reference: 1,700 kWh/kWp/year; PR 78%; additional energy correction 5%. Generation = 3,000 × 1,700 × 78% × 95% = 3,779,100 kWh/year. The 1,700 assumption is neither site PVOUT nor irradiation in kWh/m². Do not apply PR again to a net PVOUT estimate without checking its loss boundary.

Without BESS, 3.506 GWh of solar directly serves demand and 0.274 GWh is curtailed. With 5 MWh BESS, 0.274 GWh charged delivers 0.232 GWh, with 0.041 GWh lost; PLN imports fall from 5.254 to 5.022 GWh. That incremental energy is worth approximately IDR241 million/year gross at the assumed IDR1,035.78/kWh, before battery cost, O&M, tax and ageing. A battery shifts energy; it does not generate it.

The energy-cost objective selects 2.5 MWp PV with no BESS on the tested grid. Assumed battery cost outweighs the value of recovered solar. This does not establish that batteries never pay: resilience, production losses during outages, diesel costs and time-of-use tariffs can change the decision.

A separate screen requires a protected reserve of 0.5 MW for 2 hours = 1 MWh AC. The lowest tested combination becomes 2.5 MWp PV + 2 MWh BESS / 0.8 MW PCS, holding the normal-operation SOC floor at approximately 74.2%, above the 20% minimum. This excludes auxiliaries, ageing, temperature effects, motor starts and repeated outages; actual reserve sizing may need to be larger.

A 5 MWh battery provides about 3.23 MWh AC from 90% to 20% SOC: approximately 3.23 hours at a 1 MW load. If an outage starts at 40% SOC, only about 0.92 MWh remains above the minimum. Neither number is a backup guarantee.

Assumptions: PV IDR9 million/kWp (USD0.50/Wp × IDR18,000/USD); BESS including PCS IDR4.5 million/kWh (USD250/kWh), not verified market pricing. Discount rate 10%; PV evaluation life 25 years and battery life 10 years; annual O&M 1.2% and 2% of CAPEX. Total equivalent annual cost = grid energy purchases + annualised CAPEX + O&M. Capital recovery factor = r(1+r)^n / [(1+r)^n−1]. The first-year profile and tariff repeat; degradation, augmentation, tax, financing, residual value and cost escalation are excluded. This is not a cash electricity bill or bankable LCOE.

For diesel, obtain litres/hour against kW, delivered fuel cost, minimum stable load, unit availability, starts/stops and spinning reserve. For a coal plant, add part-load heat rate, fuel cost, auxiliary demand, minimum stable generation, ramp rates, minimum up/down times and start costs. Thermal optimisation requires unit commitment; changing a single tariff is insufficient. Only the PLN baseline is modelled here.

SUN can support baseline development, option sizing and scope definition, technical-commercial proposal comparison and developer/EPC discussions within the agreed engagement. A project study requires metered data, coordinate-specific weather, power quality, PCC limits, islanding requirements, protection studies, fire safety, flood levels, maintenance access, throughput warranties and end-of-life planning with responsible specialists.

Confirm the installation class and permitting pathway with PLN and the relevant authorities. ESDM Regulation 2/2024 addresses rooftop solar; it is not automatically the approval framework for every plantation ground-mounted array. No PLN approval, quota, export credit or verified carbon reduction is assumed. Engagement starts with an agreed scope and quotation; payment is offline against invoice.