Three different kinds of new load
A hot tub runs a heater and circulation pump year-round, and in a Colorado winter the heater works hard. A shop with compressors, welders, or a mini-split has irregular, sometimes high-power loads. An ADU is effectively a second household — lights, cooking, heating, and possibly a second EV.
Each shows up differently. Hot tubs are steady and predictable; shops are spiky and can matter more for panel capacity than for annual kWh; ADUs add both. Get the equipment specs from your contractor so we can estimate annual kWh instead of guessing.
One meter or two
Net metering credits generally apply to the meter the solar is connected to. If your ADU has its own utility meter, panels on the main house won’t reduce the ADU’s bill, and vice versa. Some owners put a separate small system on the ADU; others keep the ADU on the main meter so one system covers both. The right choice depends on who pays the ADU’s bill and your utility’s rules.
Detached shops and garages are often great solar roofs — or good spots for a ground mount, which we also build. Trenching to the main service is a real cost; we price it rather than assuming it away.
If you already have solar
If we installed your existing system, expanding it is straightforward to evaluate. If another company installed it, we don’t modify or take over that system; a separate new system may be possible under your utility’s interconnection rules.
Watch the rules on expansions. In Longmont, for example, systems that are new or expanded after January 1, 2025 are credited at a value-of-solar rate rather than the retail credits older systems keep through January 2040 — so expanding an older Longmont system can change the credit on the original panels too. Ask before you add.
What to do next
- 1Collect the new equipment’s specs: hot-tub heater wattage, shop tool ratings, or the ADU’s planned heating and appliances.
- 2Decide whether the ADU or shop will be on its own meter.
- 3Have your electrician confirm panel and service capacity for the new load before solar is designed.
- 4Run the electrification calculator to estimate the added kWh and solar needed.
- 5If you’re in a municipal utility area like Longmont, ask how an expansion affects your existing export credits.
FAQ
Questions we hear
Will solar on my house cover an ADU with its own meter?
Generally no — net-metering credits apply to the meter the system is connected to. A separate system for the ADU, or keeping the ADU on the main meter, are the usual approaches. Confirm with your utility.
Can panels go on my detached shop or garage?
Often, if the roof structure and orientation work. The cost of running conductors back to the main service matters, and so does the permitting jurisdiction. Ground mounts are another option we install.
Should I wait until the hot tub is running to size solar?
You can, and real usage data is useful. But a hot tub’s load is predictable enough from its specs that most people size for it up front and avoid a second project.
Does adding panels to an old system change my net-metering terms?
It can. Longmont Power & Communications credits systems new or expanded after January 1, 2025 at value-of-solar rates. Other utilities have their own rules. Check before expanding.