Handle multiple meters per meter group for Solar

[solderq35]

It seems that by the time PacificPower meters get to meter_group.js file, they are accumulated_real measurement type anyways.

However, it could be good to handle case for solar meters in the future regardless.

Other notes for adding multiple meters to Radiation Center meter group:
(This may be a good indication of future potential issues of supporting multiple-meter meter groups with solar energy type, since PacificPower uses energy_change initially)

• Measurement type is accumulated_real by the time it reaches src/store/meter_group.js, so multiple meters can be combined into one meter group for PacificPower meters without any issue
• Adding up accumulated_real values for various days seemed to sum up values from 3 meters as expected, and Inspect Element > Network makes 3 API calls at https://dashboard.sustainability.oregonstate.edu/#/building/59/2
  • For February 15 (Unix: 1708041599), meters 129 and 139 have data while meter 148 does not. As expected, the accumulated_real value shown for February 15 (for the Radiation Center meter group) is the sum of meters 129 and 139 only.