What does this hypothetical New Jersey project assume?
This is an invented hotel account in the PSE&G service area comparing three operating cases for a 30-day teaching month. There is no client, installed system, developer proposal, approval, or observed outcome. Assume the hotel requires 60,000 kWh and has a baseline monthly peak of 180 kW. Assume solar produces 15,000 kWh during the month. These values are not production estimates or consumption benchmarks.
Assume an imported energy component of $0.10 per kWh and a simplified demand component of $12 per kW-month. Both prices are invented. The worksheet excludes other supply, delivery, rider, tax, capital, maintenance, financing, and replacement costs. It assigns zero value to exports and no incentive or certificate revenue. That narrow boundary is necessary to keep the arithmetic separate from a complete investment analysis.
An behind-the-meter energy balance reconciles what the hotel consumes with direct generation, storage discharge, imports, exports, and losses. The bills hub explains why the energy balance and invoice components need distinct treatment. A physically consistent worksheet can still have incomplete economics if it omits actual tariffs or project costs.
Which approval and tariff questions are specific to New Jersey?
New Jersey’s interconnection rule adoption R.2026 d.010, effective January 5, 2026, supplies dated background. It lists a February 27, 2026 expiration date; confirm its present status against subsequent rules and the serving utility’s current process. This document does not establish approval for the hypothetical system. Verify design, export limits, the applicable tariff, and permission to operate before treating generation or storage as available for a purchasing forecast.
The worksheet assigns no export credit or incentive. Verify export compensation, approvals, and supplier terms separately before adding them to an investment analysis.
DOE’s distributed-energy and microgrid guidance explains the roles of distributed generation and storage. It does not establish that an ordinary grid-connected solar installation provides hotel backup power. Any continuity function requires its own engineered design and operating review.
How does solar alone change the assumed energy flows?
In the solar-only case, assume 10,000 kWh of generation is used directly by the hotel and 5,000 kWh is exported. Generation reconciles as 10,000 + 5,000 = 15,000 kWh. Hotel consumption reconciles as 50,000 imported kWh + 10,000 direct solar kWh = 60,000 kWh. Zero export credit means the 5,000 kWh is tracked physically but contributes no revenue to this calculation.
Imported energy costs 50,000 × $0.10 = $5,000, compared with $6,000 before the project. The $1,000 difference is an assumed energy-component result, not project savings. It does not include capital or other operating costs, and it should not be multiplied by a project lifetime without a supported annual production and cost model.
For demand, assume solar lowers the daytime peak from 180 to 150 kW, but an evening hotel peak remains 170 kW. The simplified monthly maximum is therefore 170, not 150. Its demand component is 170 × $12 = $2,040, compared with baseline $2,160. The modeled combined components are $7,040 rather than $8,160, a difference of $1,120.
How does storage change the balance?
In the combined case, assume the battery receives 4,000 kWh that otherwise would have been exported. Assume round-trip efficiency of 90%, producing 3,600 kWh of useful discharge and 400 kWh of losses. Remaining exports are 1,000 kWh. Solar generation reconciles as 10,000 direct use + 4,000 charging + 1,000 exports = 15,000 kWh.
Hotel use now reconciles as 46,400 imports + 10,000 direct solar + 3,600 battery discharge = 60,000 kWh. Storage charging reconciles as 3,600 discharge + 400 losses = 4,000 kWh. Do not count the 4,000 charging quantity and 3,600 discharge as two contributions to hotel use. That would double count energy passing through the battery.
| Assumed monthly flow | No project | Solar alone | Solar plus storage |
|---|---|---|---|
| Hotel consumption | 60,000 kWh | 60,000 kWh | 60,000 kWh |
| Solar generation | 0 | 15,000 kWh | 15,000 kWh |
| Direct onsite solar | 0 | 10,000 kWh | 10,000 kWh |
| Battery charging | 0 | 0 | 4,000 kWh |
| Battery discharge to hotel | 0 | 0 | 3,600 kWh |
| Storage losses | 0 | 0 | 400 kWh |
| Exports | 0 | 5,000 kWh | 1,000 kWh |
| Grid imports | 60,000 kWh | 50,000 kWh | 46,400 kWh |
Can the assumed battery cover the modeled peak period?
Assume the battery can discharge 30 kW for four hours daily, requiring 120 kWh of usable discharge each day. Over 30 days, that is 3,600 kWh, matching the monthly useful discharge. Its average daily charging is 4,000 ÷ 30, or about 133.33 kWh; at the assumed 90% efficiency, that supports 120 kWh of discharge. These are simplified repeating-day assumptions, not equipment sizing evidence.
Assume the 30 kW discharge lowers the 170 kW evening hotel peak to 140 kW. The 150 kW daytime peak then sets the modeled monthly maximum. Demand costs 150 × $12 = $1,800. Imported energy costs 46,400 × $0.10 = $4,640, producing $6,440 of combined components. The difference from solar alone is $600: $360 energy and $240 demand.
Check power and duration separately. A battery able to provide 120 kWh but only 10 kW would not perform the assumed 30 kW response. Conversely, 30 kW output with only 60 usable kWh could sustain that output for two hours, not four. A real design needs the complete sequence, reserve requirements, weather variation, and controls before the forecast accepts either effect.
What changes if a different interval sets the peak?
Suppose the battery acts as planned but a separate late-night interval reaches 175 kW when it is not discharging. The monthly maximum becomes 175 rather than 150. At the assumed demand component, cost is $2,100. Combined with $4,640 imported energy, the components total $6,740. The battery’s incremental modeled difference from solar alone is now $300 rather than $600.
DOE’s utility-rate evaluation guidance supports checking the actual account profile and demand method. A tariff floor, ratchet, time period, or other determinant can also change the result. Do not substitute the example’s simple monthly maximum for the actual PSE&G account rules or assume a response removes every billed demand component.
There is a price sensitivity as well. If the invented imported energy component falls to $0.06, storage’s 3,600 kWh import reduction is worth $216 rather than $360. With the original $240 assumed demand difference, incremental modeled benefit is $456. No probability or future price direction is assigned. Project economics need these sensitivities and the omitted costs, not only the most favorable operating case.
How are supply contracts and renewable attributes reviewed?
Tell prospective suppliers about the proposed generation and storage dates and changed imported-load profile. Compare current and post-project scenarios. Ask how the agreement treats lower purchased volume, exports, new equipment, or a delayed commissioning date. A project estimate should not become an unrestricted right to revise contracted volume.
EPA’s REC guidance explains that renewable attributes can be separated from electricity. Review project ownership, certificate allocation, and any retirement requirement before making an environmental claim. This example assigns neither certificate value nor a renewable-use claim. Electricity-flow math does not establish attribute ownership.
For brokerage compensation in a procurement comparison, disclose whether it is embedded or separate and include it once. The assumed imported energy component contains any embedded fee for this teaching calculation. A separate actual fee, project developer payment, or storage service cost needs its own disclosed treatment and should not be silently netted against exports.
What should be verified before an owner uses the worksheet?
- Obtain site-specific generation and storage design with usable energy and power constraints.
- Confirm the utility process, current tariff, export arrangement, and permission to operate.
- Reconcile direct use, charging, discharge, losses, imports, and exports without duplication.
- Test peak timing, shorter discharge duration, and changed energy components.
- Add complete project costs and separately verified incentives and attributes.
- Review supplier volume treatment, compensation, commissioning, and invoice evidence.
The Pennsylvania charging example adds consumption instead of generation. The New York water-heating example changes fuel requirements, while the five-property example coordinates account economics. Keep their physical and contractual boundaries distinct from this solar-storage balance.