Economics

This page collects the money results of a scheme. The priced bill of materials comes from the configurator engine - the same call the configurator page makes - so item, model, specification, quantity, unit price and subtotal are the engine result for your input, together with the automatic cross-checks (voltage drop, cable thermal minimum, protection selectivity, N-1 outcome, harmonics, derating). Prices are FOB Qingdao reference prices from the engine price library in USD, excluding sea freight, insurance, duties and installation consumables, with installation and commissioning charged at 18 % of the equipment price. The loss blocks come from the design engine (design.lossAllocation carries the per-device table): the network loss plus the per-device allocation - transformer core loss P0 (constant), copper loss Pk x (S/Sn)2, cable and busbar I2R - each device on its own row with its share, reconciled against the load-flow network loss within 0.5 % (the reference case deviates 0.065 %). The economics study (POST /api/design/study with study 'all' and 'evalall', read back as study.ems / study.lcc / study.dispatch / study.demand / study.losses) then adds a 25-year life-cycle cost at a 6 % discount rate (capital + O&M + loss energy + storage replacement every 10 years, plus the levelised cost per kWh), an hourly storage dispatch with time-of-use arbitrage and PV self-consumption, a demand-charge comparison that scans for the storage size with the best net present value, the payback period and the avoided CO2. Transformer loss and efficiency follow IEC 60076-1 practice and GB 20052 typical values; battery studies follow IEC 62619 and GB/T 36276.

This is the page a buyer actually reads: what does the scheme cost, what does it save, and when does it pay back. Because the BOM, the losses and the life-cycle cost all come from the same engine run, the quote and the technical numbers cannot drift apart - and the loss reconciliation shows whether the saving claimed by a storage option is consistent with the losses the same run reports.

Input = the scheme JSON plus the load profile, the tariff region or custom prices and the storage size. Chain: the configurator call prices the equipment list (FOB reference prices, then the 18 % installation rate); the design call returns the network loss and the per-device allocation, reconciled to the load-flow loss within 0.5 %, with the I2R-only column shown separately because it excludes magnetising core loss; the economics study solves an hourly load flow over the representative days, charges in the valley and discharges at the peak within the SOC window, and discounts the resulting cash flows at 6 % over 25 years with a storage replacement every 10 years, giving the LCC breakdown, the levelised cost per kWh, the optimal storage size by net present value and the payback. Output = the engine values, never a browser-side recomputation. Linkage: transformer capacity and compensation change the BOM, the losses and the loss energy; the tariff changes the dispatch and the payback; the storage size changes the investment, the replacement cost and the saving.

The engine reference case (600 kW load, one 1000 kVA transformer, 150 kvar compensation, MV switchgear) allocates 9.246 kW of losses and reconciles to 9.240 kW of load-flow network loss — a 0.065% deviation: the largest single item is the 2.726 kW cable feeder (29.48%), followed by the transformer copper loss 2.240 kW (24.23%) and its constant core loss 1.150 kW (12.44%). On the economics side a 2000 kW scheme with 480 kWp PV and 3000 kW / 6000 kWh storage shows a 25-year LCC of $2,712,421 (capex $477,500 + O&M $61,041 + loss energy $1,168,769 + replacement $1,005,111) at a levelised cost of $0.014/kWh, an annual storage saving of $225,661 on a $900,000 investment (about 4.0 years payback) and 292.38 tCO₂ avoided per year from the PV.

Loss modelling follows IEC 60076-1 / IEC 60364-5-52 practice with transformer losses split into no-load P0 and load loss Pk×(S/Sn)²; the loss-allocation report reconciles to the load-flow solution within 0.5% and discloses what is not modelled (capacitor dielectric loss, reactor loss, busbar contact resistance, harmonic extra loss). The LCC uses a 25-year life and a 6% discount rate; the EMS dispatch solves an hourly load flow over four representative days (spring / summer / autumn / winter) and scales to 365 days; transformer efficiency references use GB 20052 typical values; demand charge compares a demand-based against a capacity-based basic charge. Quotations are FOB Qingdao reference prices in USD and exclude sea freight, insurance, destination duties and installation consumables; installation & commissioning is 18% of the equipment price.

How accurate is the BOM and the quotation?

The BOM is not a guess: it comes from the same configurator engine call the configurator page uses, so the item list, quantities, models and total are the engine result for your scheme input, and the cross-check block lists the automatic checks with their values. Prices are FOB Qingdao reference prices from the engine price library (USD, excluding freight, insurance, duties and installation consumables); installation & commissioning is charged at 18% of the equipment price. A firm quotation is issued after engineering review.

Where do the loss numbers come from?

From the design engine: transformer loss is P0 + Pk×(S/Sn)², cables and busbar / switchgear links take the branch I²R of the real load-flow solution, and the MV incoming cable segment is listed as its own row. The allocation is reconciled against the load-flow network loss with a 0.5% tolerance (the reference case deviates 0.065%) and the I²R-only figure is shown separately because it excludes magnetising core loss — nothing is silently invented, and reactive-compensation loss is disclosed as a range instead of a made-up number.

Why is the payback different between cards?

Because they answer different questions on the same engine data: the EMS card cycles the storage you actually configured (so its saving and payback reflect that size), while the demand card scans a grid of smaller storage options and reports the one with the best net present value. Both use the same hourly load flow, the same tariffs and the same 25-year evaluation window, so you can compare “what I installed” against “what would be optimal”.