Here’s some information on how the Customer Grid Supply-Plus (CGS+) rate program that you will fall under after solar is installed would work. There is a minimum HECO bill for residential customers of $25 which basically covers the electric company’s fixed cost of providing and maintaining electric service to your home & neighborhood.


For your power usage, the solar will offset all your daytime electricity usage, excess power will charge the batteries, and once the batteries are fully charged, you will send power back to the HECO grid and get credits at 10.08 cents per kWh. At nighttime after the sun sets, your Tesla batteries will discharge to meet the power needs of the home, once the batteries are fully discharged, you will begin to purchase power from the grid. Right now, HECO’s ‘R’ rate is about 25 cents, so you would pay 25 cents less than the 10 cents credit you have made during the daytime for a net cost of 15 cents per kWh.

Customers have a tendency to use more power overall after they’ve installed solar because it seems a bit more guilt-free, so our system is sized based on your previous total annual electricity consumption of ~16,000 kWh. 

So what your monthly bill is can fluctuate depending on a number of things:

  • Seasonality:  Summer months have more intense sunlight and longer days so the PV system will produce more power during the summer.
    • Customers tend to use more power in the summer months also if they’re running their air conditioning more often.
    • You may build up some additional credits during summer time that will be carried over and used up in the winter time where the sun is less intense and you need to purchase more power from the grid.
    • The goal is for the credits to balance out over the 12-month billing period
  • Weather Patterns:  as you know in Hawaii, there are micro-climates and weather patterns (long stretches of rainy days, etc.) that will impact the solar production on a monthly basis
  • Home Power Consumption Habits:  It’s helpful to be more conscious of your electricity usage after you’ve installed your solar energy system, because the higher the percentage of your power consumption that you can shift to the daytime, the greater economic benefit you will see from the system. So certain daily habits like charging your EV during the day, doing laundry during the daytime, etc. will benefit from requiring less power from the grid during night-time hours.
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