Saturday, April 15, 2023

SunPower Solar System online

 



We had a SunPower solar system installed on our house.  It consists of 20, 400W panels, 14 on the East roof and 6 on the South.  The total system generating capacity is 8kW.  Since the panels are on different roof angles, it is unlikely to get that 8kW since they will reach peak output at different times.  

We still have net metering here so we did not install a battery system yet.  Net metering allows us to sell our excess power back to the energy company and accumulate a positive balance with the utility.  During the times of year with higher solar generation than consumption we build up a credit which can be used during the summer months to pay for the usage that exceeds our generating.  Basically, you somewhat use the grid as a enormous long-term battery.  I believe as more solar powers the grid, these net meting plans will go away so I wanted to get in while they were still available.  The 30% tax credit was also a huge incentive.  Our system went online in April, the same month the utility raised the rates over 6% making the value prop that much stronger.   

Utility power meter for solar showing energy sold back to the grid (arrow left)

Here is what the dashboard shows for a full day.


The system requires changing your power plan and your house power meter with the utility.  The new meter shows which direction power is flowing.  You can also see the daily summary on the utility website.

The grey shows the amount of energy the solar generated and the house used.  The green shows the net power we sold back to the grid.  The black shows the amount beyond what we generated in solar that we had to buy from the grid.  April 12 was a cloudy day and April 13 was sunny.  Even on that cloudy day we generated most of what we used.  

Our system is sized to deliver 100% of our annual electric energy needs based on prior power consumption. It does not generate 100% of our peak power needs.  The system also does not supply power if the grid goes down.  We would need a battery system for that.  At some point it will make sense to add a battery system but right now with net metering and a very stable grid here it does not seem cost effective.  I do expect the cost of home energy storage to drop and the systems improve going forward.