Backup AC charge controller?

[jsz0]

I'm in the early stages of designing a small solar system I can use to supplement my commercial power. My goal here is to have all of my lighting running off the solar system and also be able to charge some small electronic devices. I have a pretty good idea what I will need for panels and batteries. Luckily I have a south facing garage near my house with no nearby trees so I expect to get pretty good sun coverage. I want to plan though for the possibility that I may have 3-5 days of cloud coverage at times. I would like to have the system setup so during the daytime hours of good sun coverage I charge the batteries from the panels but at night, or in extended periods of cloud coverage, if needed, I could dip into commercial power with an AC charge controller. My question is if there's any easy way to automate this? For example is there such thing as an intelligent charge controller that can be programmed to switch to AC at night and then back to DC during the day? Can it do this intelligently based on the load from the solar panels? Perhaps just use a timer to flip it over at night for a few hours?

[Sunking]

Exactly why would you want to use solar battery if you have commercial AC? Do you just like paying 10 to 20 times more for electricity?

To answer your question just use a standard plug in wall charger when needed. To my knowledge there is no commercial device to do what you want as there is no demand for it. Hybrid grid tied inverters can do that, but that is not what you have.

[jsz0]

My goal is to have a backup power source that doesn't require a generator / fuel and the noise that comes along with it. I already have 3 deep cycle batteries which I charge via AC and they provide me with 2-3 days of coverage for lighting and enough power to keep my phone charged. I would like to expand this to give me a few hours of laptop runtime as well. So in this case solar is for redundancy past the 2-3 days of coverage commercial power provides. If I can keep them topped off with solar alone that's fantastic but not really my primary concern here. I just need the battery pack to be ready for action at all times. If it comes from commercial power or solar -- doesn't really matter.

[Mike90250]

Just a side note, the laptop wont be much good when the signal boosters for the fiber/cable/wifi go down 3 hours after the power failure. Much of the east, currently have so utilities except for the copper phones. Cell service is coming back slowly, and cable/fiber will be last.

[jsz0]

In the north east after Irene Verizon did a pretty good job keeping their cellular data up. AT&T did not. I would agree it's definitely not something you can count on having in that type of situation. One of the reasons I always keep a small collection of music, ebooks, and movies on my laptop. Plus there are lots of things you can do without Internet access in general. If you have spotty cellular data coverage you can catch-up on e-mail and just que it up to send when you're back online. My current setup did a pretty good job running my laptop for a few days but I did have to offset the usage by losing some lights while I was using it to conserve battery.