Charge rate questions?

Re: Charge rate questions?

vtmaps wrote: »

Yes, but 10% is a rule of thumb, not a required number. What's important is that you make enough power to satisfy your loads and your battery.

As far as BB's calculations, he usually derates the solar panels to about 77% of their capacity. That is also a rule of thumb that may not apply to every system. Your 40 amps today is 90% of your panels rating, but was transient... you won't see that all day every day.

Bottom line: Are your batteries getting charged all the way? If so, you do not need more panels.

--vtMaps

The system is being set up primarily as a backup, and also as a bit of a hobby as I am here pretty much all of the time I am not working. I care for my Father who is on oxygen 24/7, who needs AC and a dehumidifier as well. The house is otherwise all electric with one big window shaker air conditioner using a couple of fans for air distribution to the rest of the small house.

Heat is currently a couple of 240 volt forced air resistant wall heaters. There use to be one in each room, but I have removed all but two. I replaced the refrigerator a couple of years ago when I connected it to my little 2500 watt generator, and it would killed the engine.

I am the first residential solar customer that I know of in my little town and maybe the county that will be grid tied. So far the inspector doesn't really know what to do with me, so I haven't been able to see what the system will support because it is not connected to the house yet. I am waiting on the inspector to approve or modify my plan.

I realize I have a lot of conservation work to do yet, but I gave up with the "kill a watt" pretty soon into the project. I would like to be able squeeze as much as possible out of the system without murdering the battery bank. Then again if I do kill the bank I may go up in capacity which will once again require more panels. This just keeps going round and round.

Thanks

Dennis

Re: Charge rate questions?

Cariboocoot wrote: »

It won't sell its rated output (3600 Watts) if it can't produce it: you can't get 3.6 kW from a 2.3 kW array. Pulling power from batteries means the Voltage sags below the SELL level. To actually sell full capacity you'd need an array around 4.6 kW. At that point you'd be better off contemplating adding the 2kW 'extra' to a standard GTI if you don't need the back-up capacity; it would be more efficient.

This is something new to think about. Even on the Outback website there is very little operational information about their equipment. It more or less states that you can sell power to the grid without any specific info on how much.

Using the information you just shared I will likely increase the array to 3500 watts, (four more panels) and leave it at that. If I ever need to go further I would consider buying another inverter and stacking for split phase 240. This would give me some redundancy.

Then again new emerging technology is changing pretty fast and that in itself can change your plans. If I had known 6 months ago when I bought this inverter I could have got a 4 KW Radian for $2700.00 I would have given one of those a hard look. Who knows someone might come out with a 20 gigawatt cold fusion generator next week that runs on septic tank sludge for a hundred dollars, and make solar power a mute point.