Author: Mary Prasanna
ISO-New England released ISO-NE’s 2025 CELT Report: Tracking Growth in Distributed Energy Resources (2025 Forecast Report of Capacity, Energy, Loads, and Transmission ) which gives us insight into BTM-PV projections for the next 10 years. Data collection for storage devices (Battery) is underway, and these projections are expected to be added in future edition of ISO-NE’s CELT report.
End-of year installed capacity in MW and forecast for future years is shown in below table.
End-of year Installed Capacity and Forecast
| Category | 2024 | 2025 | 2030 | 2034 |
| PV (FCM1 & Non-FCM) | 3092 | 3314 | 4589 | 5382 |
| BTM PV | 4542 | 5002 | 7173 | 8961 |
| Total | 7634 | 8316 | 11762 | 14343 |
Year-by-Year Projection of PV Resources in ISO-NE Region Through 2034
The above graph gives the year-by-year projection of PV resources in the ISO-NE region till the year 2034. The contribution from BTM-PV is expected to increase in the next 10 years.
At the end of 2024, the region had 4,542 megawatts (MW) of installed BTM-PV nameplate capacity. It is projected to be 5002 MW, 7173 MW, 8961 MW by 2025, 2030, 2034 respectively. It is expected to more than double over the next 20 years, rising to 11,156 MW in 2045.
The below table shows the annual increment in nameplate rating for different states. Massachusetts (MA) taking the lead in installation followed by Connecticut (CT).
Annual Total Incremental MW – Nameplate Rating
| Category | States | Annual Total Incremental MW – Nameplate Rating | Totals | ||||||||||
| 2024 | 2025 | 2026 | 2027 | 2028 | 2029 | 2030 | 2031 | 2032 | 2033 | 2034 | |||
| Behind-the-Meter PV | Connecticut (CT) | 947.5 | 177.2 | 174.6 | 170.5 | 170.4 | 166.0 | 159.4 | 160.7 | 160.7 | 142.5 | 121.5 | 2,551.2 |
| Massachusetts (MA) | 2,028.7 | 147.9 | 68.2 | 76.4 | 158.9 | 160.2 | 156.6 | 160.1 | 160.3 | 143.0 | 123.4 | 3,383.9 | |
| Maine (ME) | 596.1 | 43.1 | 34.7 | 35.6 | 34.1 | 39.7 | 41.4 | 45.5 | 46.7 | 43.2 | 38.5 | 998.6 | |
| New Hampshire (NH) | 269.7 | 34.9 | 36.2 | 44.0 | 47.5 | 52.5 | 52.8 | 56.4 | 58.1 | 54.8 | 49.8 | 756.7 | |
| Rhode Island (RI) | 170.9 | 23.7 | 23.7 | 18.4 | 28.6 | 26.6 | 22.4 | 19.4 | 19.5 | 17.2 | 14.6 | 385.1 | |
| Vermont (VT) | 528.6 | 33.1 | 33.4 | 33.9 | 34.2 | 34.7 | 35.3 | 37.8 | 40.7 | 39.3 | 34.6 | 885.5 | |
| Behind-the-Meter Total | Annual | 4,541.6 | 460.0 | 370.7 | 378.8 | 473.7 | 479.8 | 467.9 | 479.9 | 486.1 | 440.1 | 382.3 | 8,961.0 |
| Cumulative | 4,541.6 | 5,001.6 | 5,372.3 | 5,751.1 | 6,224.8 | 6,704.7 | 7,172.5 | 7,652.5 | 8,138.5 | 8,578.6 | 8,961.0 | 8,961.0 | |
The peak demand is the time when electricity usage from grid reaches its maximum. The peak demand on the grid is typically in the early evening, but the solar production is strong at midday. The impact of increased capacity of BTM-PV on system peak is considerably low.
In summer 2024 only 6% (1520 MW) of reduction is observed in estimated peak due to BTM-PV. It is estimated that over the next 10 years, the forecasted summer peak reduction because of BTM-PV will remain at the same level. But this trend may not be same afterwards because of the electrified vehicles which may bring summer peaks to nighttime. It is observed that BTM-PV has no impact of 2024/2025 winter peaks. It is forecasted that winter peaks may shift towards the morning in 2030s and BTM-PV may impact its peak.
Summer Peak Load forecast (MW)
| Forecast and Capabilities | Summer Peak Load forecast (MW) | |||
| 2024 | 2025 | 2030 | 2034 | |
| Gross Load | 26,352 | 26,539 | 27,495 | 28,777 |
| Behind-the-meter PV (Estimated Summer Seasonal Peak Load Reduction) | 1,520 | 1,736 | 1,938 | 1,879 |
| Net (with reductions for BTM PV | 24,832 | 24,803 | 25,557 | 26,898 |
Winter Peak Load forecast (MW)
| Forecast and Capabilities | Winter Peak Load forecast (MW) | |||
| 2024 | 2025 | 2030 | 2034 | |
| Gross Load | 20,059 | 20,056 | 22,452 | 26,422 |
| Behind-the-meter PV (Estimated Summer Seasonal Peak Load Reduction) | 0 | 0 | 168 | 402 |
| Net (with reductions for BTM PV | 20,059 | 20,056 | 22,284 | 26,020 |
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