Princeton Municipal Light Department

Massachusetts Utility Interconnection & net metering rules

Spot something wrong?

Tariffs and interconnection rules move often. If something here is out of date or missing, tell us and we'll fix it.

Report a correction
Net Metering AllowedYes
Line Taps AllowedYes
Load Taps AllowedYes
AC Disconnect RequiredYes

Net metering & export

Net Metering Allowed
Yes
TOU Utility
No
Post Solar Billing Method
Export Rate
Solar Export Type
Avoided Cost
Net Excess Generation Notes

PMLD will credit the solar owner’s account in dollars ($) on a monthly basis for the avoided cost for exported power. PMLD will round the consumed power up to 200 kWh per month minimum should actual consumption be less. Any annual net credit greater than $25 can be requested by check each April for the previous April through March time period. Net credits not claimed by April 30 will be applied to the Town of Princeton’s electric bill.

Rebates Offered
No

Interconnection & taps

Approval Req To Install
Yes
Line Taps Allowed
Yes
Load Taps Allowed
Yes
Tap Criteria

Line Side Tap allowed per NEC

Automatic Transformer Upgrade Size
0
Meter Aggregation Allowed
No

System size & offset

System Size Restrictions
30
System Size Restriction Type
AC kW
System Size Battery Included
No
System Size Includes Existing Systems
No
Offset Type
Combination
Offset Value
100
Offset Calculation Basis
Historical
Offset Calculation Period
12
Industry Standard Watts Sqft
2
Offset Calc Tool
Historical Usage

Metering & disconnect

Production Meter Required
No
AC Disconnect Required
Yes
AC Disconnect Labeling
Visible Lockable Labeled Disconnect
Allowed Meter Adapter
None

Plans & docs

Site Plan Reqs

Standard

SLD Reqs

Standard, PE stamp required

Electric Service Reqs

Systems 30kW or Less:

  • PMLD will require an external disconnect switch at the PCC
  • Must be gang operated, have a visible break when open.
Placards
  • All meter enclosures shall have a red plastic placard with white embossed writing attached by rivets either directly above or below the meter.
  • The embossed wording will be "Caution, Interconnected Generator".
  • The attached placard will be a minimum of 1 1/2" high and 3" wide.
  • The placard will be provided by PMLD to the customer/installer and be properly installed prior to PMLD's final witness test and approval.
Electrical Stamp Required
Yes
Equipment Approvals
California Energy Commission
Meter Num Req SLD 3LD
No
ESID Num Req SLD 3LD
No
Website
link
Phone
(978) 464-2815

Other details

Mod Swap Requires Planset
Yes
Compiled from public records, 2026. Tariffs and interconnection rules change; verify with Princeton Municipal Light Department before you rely on this. The useful move: if an installer says you need a main panel upgrade, ask how these tap and interconnection policies were considered first.