Activate solar in an emergency
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Plain and simple. You can't "fool" a "grid tie" inverter due to the safety software built in to it that looks for a "grid". There isn't any device that can mimic a grid to make the inverter work.Comment
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IMO Golf cart batteries would be the better choice for an AC couple 'emergency' back up system. The AC couple inverter really can't control the charge rate to the batteries when in AC couple mode. It's dumping all the surplus energy from the grid-tie into the batteries, when the batteries are full it trips the grid-tie by frequency shifting. Flooded batteries can handle overcharging much better than lithium. There are dump controllers available but that obviously adds to the cost.Last edited by nwdiver; 06-01-2019, 03:48 PM.Comment
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AC couple inverters can 'fool' a grid-tie inverter. My Magnum 4448PAE works fairly well with my 8kW SMA Sunnyboy. I can pull 2/3 fuses if I'm worried about the SMA over powering the Magnum since I should have 2 Magnums to absorb the output of the SMA. There are a few other AC couple capable inverters out there like the Outback radian. As far as I know all grid-tie inverters are able to AC couple since AC coupling is designed around the UL1741 standard.
IMO Golf cart batteries would be the better choice for an AC couple 'emergency' back up system. The AC couple inverter really can't control the charge rate to the batteries when in AC couple mode. It's dumping all the surplus energy from the grid-tie into the batteries, when the batteries are full it trips the grid-tie by frequency shifting. Flooded batteries can handle overcharging much better than lithium. There are dump controllers available but that obviously adds to the cost.
The 8kW SMA Sunnyboy inverter has the secure power option which allows "2kW" of the solar array to generate power without the grid but never the entire 8kW. That type of inverter is one of the 3 non standard kind I mentioned in my post.Comment
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You did not read my post completely.
The 8kW SMA Sunnyboy inverter has the secure power option which allows "2kW" of the solar array to generate power without the grid but never the entire 8kW. That type of inverter is one of the 3 non standard kind I mentioned in my post.
Last edited by SunEagle; 06-01-2019, 06:21 PM.Comment
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there are several YouTube videos on how to emulate the grid, and accomplish what you are after. it needs a little bit of work and you need some creativityThose who do, do it!Comment
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I understand that someone will find a way to DIY a system that bends the rules but I will not condone those videos on this forum.
If you don't like my response then take it up with the Admin.Comment
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Originally posted by nwdiver
Both Magnum and Outback have AC coupled inverters specifically designed to 'fake out' the grid tie inverter. It's as safe as any other PV system.
https://www.magnum-dimensions.com/si...g-Rev-5-10.pdf
These are NOT "faking out" the grid tie but actively managing it. The OP was asking about a small off grid and car battery system which is NOT going to be safe or able to handle anywhere close to 7.6kW of charging.OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNHComment
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Yes, AC coupled inverters are designed to actively manage the output of the grid-tie. Which is why 'fake out' was in 'quotations'. I agree that ~9kW of AC coupled inverter would be the right way to do it but even that isn't really that expensive. <$5k probably.
Depending on the inverter it could also be possible to SW limit a 8kW to ~4kW allowing them to safely limit the output of the grid-tie so they could AC couple to a smaller inverter 'in an emergency'. Is that the theme of this thread? Solar in an Emergency?
And the video I linked to wasn't some crazy DIY'r it was a legit PV sales site simply explaining how AC coupling works....Last edited by nwdiver; 06-01-2019, 06:43 PM.Comment
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And I do not feel that any youtube video that shows someone how to fake out the grid tie inverter is safe. Especially for people that can't determine the difference between a kW / kWh or understand the requirements for proper over current protection.
I understand that someone will find a way to DIY a system that bends the rules but I will not condone those videos on this forum.
If you don't like my response then take it up with the Admin.Those who do, do it!Comment
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as for <$5k possibly could get a 9kw inverter capable of AC coupling and management for under $5k but would also need a battery capable of taking a 7.6kW charge and various electrical components that would likely drive up the cost. It is all a far cry from OPs original question of a car battery and small inverter...
What If I took a car battery and a small inverter and put power to those wires? Would that activate the inverter?
OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNHComment
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Of all the different types of installs an AC coupled is the most critical to have a knowledgable person configure and maintain is it has the most potential for danger from a configuration problem...and at the same time AC coupled are the most complex (with regard to residential systems of the various type of configurations common in residential, string, optimized, micro, DC coupled bimodal, AC coupled).
Thus one should be very cautious in any AC coupled advice givenOutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNHComment
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