John Perlin, Solar Energy “Scholar in Residence”
2GreenEnergy intern Fabio Porcu and I spent a good portion of the day yesterday with my colleague John Perlin, scholar in residence at the University of California at Santa Barbara. Last year, I conducted a series of interviews with John in which he walked me through the highlights of his popular book on the history of solar power: “Let It Shine, the 6000 Year Story of Solar Energy.”
In our talk with him yesterday, John not only showed us UCSB’s new 420 KW solar PV array whose construction he had overseen, but he walked us through some of the peripheral technology that enables huge quantities of solar to be integrated into the grid mix, e.g., this energy storage device, the “charge controller.”
And pictured in that article is the exact Outback charge controller I use in my system.
That’s terrific. Do you see this becoming extremely popular (as Perlin suggests)? He points to this device as the cure for the “duck curve.” http://2greenenergy.com/2015/04/14/demand-for-energy-storage-in-a-changing-world/
Well it will certainly help if house hold battery storage becomes the rage depending on the battery type used. I think that solar and wind energy stored and used in the house, even with all the inefficiencies of charging batteries and using inverters, is still probably far more efficient than grid delivered power and the inefficiencies associated with that. I have read some studies that say only 35% of the power generated at a central plant actually arrives at the household after losses from the grid delivery system.
In my case I have a 500 AH (about 6kW) battery pack charged by that charge controller. If I don’t use all that energy and the batteries get fully charged early in the day then the charge controller will “choke” the panels down to avoid overcharging the batteries. I have come home from work to find that the charge controller has spent 5 or more hours in Absorb and Float mode meaning the panels have been choked down for that entire time and not generating at their max simply because there is no place to put all that energy.
When I am home I use that power to do things like loads of wash or run the dishwasher or make coffee or make sure the fridge is running on that power instead of grid power. This is helping that “duck curve”. When I am not home that doesn’t happen. I already have moved everything I can onto running directly off the batteries as it is. Anything that charges such as cell phones or the AV control system I have or rechargeable batteries of every kind that would normally run off a wall wart is plugged into the batteries using cigarette lighter chargers as you would in a car eliminating most of my “phantom loads”. All of my landscape lighting, porch lighting, flag spot and so forth are also totally running on the battery controlled by a light sensor.
Since the charge controller manufacturers seem to only care about charging batteries and choking down the panels when the batteries are charged, they provide no direction of power to any other load to keep the panels generating at full capacity and are, from everything I can gather, completely uninterested even though that is the device that has the best knowledge of the state of charge of the batteries. Therefore I am working on an Arduino based controller to manage and distribute the excess power to keep the panels operating at full capacity. My inverter can be controlled remotely so I can operate it from my controller and have it turned on when there is excess energy so it will power things in my house instead of grid power. Even with that I consider it highly likely that I will not be able to divert all the excess power and am looking for more loads to divert power to. I will be able to control as many as 8 loads.
That is my current “big” project.
Brian