# Transfer Switch with Solar ?



## dronai (Apr 11, 2011)

Have a customer who wants a manuel transfer switch installed on his residence, but may want to install future solar power.

Solar companies sales people told him that if there was a power outage, the solar *would not* be providing another source.

That doesn't sound right to me. The solar panels to the inverters, to the Main panels 2 pole CB Correct ? 

Backfeeding the busbar.

So a manuel transfer switch would not work, unless the CB was shut off from the inverter correct ?


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## Jlarson (Jun 28, 2009)

dronai said:


> Solar companies sales people told him that if there was a power outage, the solar *would not* be providing another source.


Not totally true, you can do grid tie installs with batteries and get back up power when the grid goes off line. A normal non battery inverter shuts off when the grid does. 

If you don't do batteries and just bring the solar into the main panel then have the xfer switch to a generate panel all will be ok without needing to shut the inverter breaker down.


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## gemiller (Sep 21, 2011)

I think what your misinterpreting is the function of a grid tie inverter. A grid tie inverter per UL1741 must shut off in X amount of milliseconds of the line side fail. This is to prevent linemen from a nasty solar array back feed on supposedly dead lines.

There is, however, ways to do this legally. You need a system that has a charge controller built in to monitor a battery bank. The company I'd most recommend after installing a few of this style system is Outback Power Systems. Midnite Solar also makes some top notch back up systems as well.

Essentially the ideal grid tie/back up system consists of this flow:

Solar Array
Charge Controller
Battery Bank
Inverter designed for battery backup systems. This can tie in to an automatic transfer switch if desired(ideal) to automatically roll to the battery back if the need would arise.


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## Rap2 (Dec 17, 2010)

Grid tie inverters do not generate a sign wave, they sync to the one provided by the utility.

But if you had a generator that automatically kicked in during a power failure it would disconnect you from the grid and the PV would sync to it and help provide power to the house during the day of course..

but unless you actually use this power during daylight hours there is no means of storing it and it would be pointless...

heh :laughing:

just food for thought, unless you are in the sticks batteries are a waste of money, the grid is the best battery ever, and you will get more bang for your buck with a generator (preferably a propane or natural gas so you dont get bad fuel over time)


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