My Tiny House on Wheels

Living Large in a Small Way


Installing switch for grid to solar and solar to grid

Posted by Jeremy on May 28, 2011 at 10:20 PM

I have been brainstorming on how to internallize my solar system controls and inverter while leaving the battery outside.  I only needed to connect the terminals to the exterior tongue end of the little house's trailer but have been unable to find such terminals in any hardware store or DIY building supply company. Then I thought... why do I have to have a specific type of terminal.  Why can't I just use a weatherproof AC outlet system to make those connections.  I thought it through and couldn't find any reason why it wouldn't work.  As soon as the weather gives me a break I will be able to test it all out and see if it will, in fact, work.  I have placed some picks of what I'm trying to do on page 3 of the photos.

I've also been looking for a switch box to run both power sourses (solar and grid) into with one out cable to the breaker box.  This way, with one flip of the switch, I can turn the grid off and the Solar on (visa versa).  I have been unable to find one.  My only option so far is to install a regular light switch (2 in 1) fixture and break the connect between them so that each switch would operate independantly with its own power supply (solar or grid).  The only problem hear is the need to make sure that you never have both switches in the on position at one time. that could cause a feedback of the AC power into the solar lines and cause damage.  I will always "secure" one in the off position to remind me to turn the other completely off before turning the other on. I will continue to look for a one switch system.

I am NOT an electrician!  So, do not do what I do until you know that it is acceptable for you and your safety.  I am experimenting.  If you have dbetter, or wiser advice please share those with me.  Simply stated:  "Show me some LOVE" :)

UPDATE!   Well, I kept thinking, which I find tiring sometimes (hehe) and it came to me that the risk would be too great if I were to double switch the grid and solar connection.  Like I said, I am no electrician, but giving myself some time to think, I realized that if even for a split second both switches were to be in the on position, I could be throwing 240 volts of electriciy into my house and system.  Thinking hurts sometimes, but the alternative would hurt even worse. Again... it is a learning experience. :)

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Reply B.S.
4:13 PM on May 29, 2011 
Have you seen Jonathon's blog and how he's going to deal with this?

The WHOLE process of building a tiny house has been a real eye opener. The problems encountered have NOT really been solved satisfactorily (insurance & permits are 2 good examples)
I really wish you well on your endeavor and hope ALL gets sorted out in the end.
Reply Jeremy
11:55 PM on May 29, 2011 
Will do my friend :)
Reply Sam
5:00 AM on October 15, 2012 
For your switch, why not use a light switch with 2 poles? IE 2 electrical switches with just 1 physical switch? They're usually used for lights that can be turned on / off from 2 locations, eg landing and hall lights.

Also you could use relays. Check the contacts are rated enough (enough current for a low-voltage supply, enough voltage for the mains!) and the coil runs off whichever voltage (12v would be simplest).

This is all quite simple electrics, I'm no expert but you could email me if you needed.
Reply Al.Coppa
4:05 AM on October 5, 2013 
I am an electrician but I am not exactly sure what it is that you are trying to do. I think that you need a 2 pole double throw switch.. Email me with more information about your plan. [email protected]


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