raydas
Solar Devotee
Posts: 166
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Post by raydas on Dec 11, 2019 13:32:13 GMT
Anybody using one? Not sure how these things work. If you have a 500W solar array setup, would this show any significant difference anywhere.
Some of the prices that I have seen, anywhere from ~$190 - ~$6550, not sure what the higher end inverter would do for you. Did not see any that would charge a battery array and funnel AC into the house, at the same time.
It seems that with a lot of sunshine, when your CC would be in float, wasting the extra sunshine, with the on grid inverter, the extra sunshine would be always in use somewhere.
If the on grid inverter had a battery array charger then you could have some sort of battery backup system, or the on grid inverter would just be powering your battery array when you lose your grid power.
This seems like an interesting subject to explore further, for those of us that are on grid.
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raydas
Solar Devotee
Posts: 166
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Post by raydas on Jan 4, 2020 12:30:24 GMT
I am still looking into the on grid inverter, and how I could best use it, in my solar system setup. I know that a lot of forum members are "off grid" or mobile, meaning RV or something like that.
Since the on grid inverter needs something like >15V DC input, I am now trying to figure out some kind of 24V DC output on my 12V DC system. At the moment I have a lot of wires and connections to deal with, and I want to minimize that, or at the very least, keep it at a minimum.
One concern that I had was that the on grid inverter setup was going to affect my electrical meter in a negative way, but so far it looks like the amount of solar power that I would be dealing with, will not create a concern.
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Post by retrodaredevil on Jan 5, 2020 0:19:53 GMT
You could try an outback FX inverter. They can charge a battery, use AC power, sell AC power and have a bunch of other features. I don't own one, but I've worked on a program that monitors outback FXs which I made before I made one for Renogy Rovers.
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Post by mediadogg on Jan 5, 2020 1:23:37 GMT
500 watts? Even if you could get the full 500 watts for 8 hours a day, that would yield only 4KWH. At 0.15 per KWH, that's about $200 a year in savings. Realistically, it will be less than $100. Is that worth the cost and expense of grid tie? And remember, the electric company will disable your inverter output when the power goes out - just exactly when you need it most!!!
The strategy I have been using is to configure my loads so that they use enough of the generated solar power that there is little to no "float" time. You should not have a problem doing that, as 500 watts is a relatively small solar array.
And so I have 4 or 5 solar arrays placed around the house to grab the sun at different times, and then arranged for a compatible load to be plugged in, that use 100% of the generated energy.
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raydas
Solar Devotee
Posts: 166
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Post by raydas on Jan 5, 2020 13:24:35 GMT
On ebay I found an on grid inverter, priced at $98.00. It is MPPT, rated at 1000W, 10V-30VDC input, pure sine wave output. For experimental purposes, I am giving this unit serious consideration. My goal is not to get money back from the electric company, not enough solar panels for that, but to offset some grid electricity.
I read somewhere that these inverters can be powered by 24V battery. So, what I am thinking is that I will pull 24V form my two batteries too power the inverter, which is plugged into the AC socket. During the sunlight, the two Rover CC will be charging the batteries, which will be powering the inverter. At night the inverter will be powered by the batteries.
In theory, when I have a power outage, on that particular circuit, I should have some AC power. Not sure how this will translate in real time.
I am still gathering some more information on that inverter, the specifics of what I would be getting for $98.00. Still some more research to do before I proceed with this.
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Post by mediadogg on Jan 5, 2020 16:59:34 GMT
I think I must not understand what you mean by an on-grid inverter. Also, what does "MPPT inverter" mean?
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raydas
Solar Devotee
Posts: 166
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Post by raydas on Jan 5, 2020 17:33:07 GMT
On grid inverter is the name that Renogy uses, is a search phrase used on ebay, and the internet. In my internet searches, some devices come up with grid-tied. I think that it is the same thing, but I am not exactly sure.
The device that I am looking at, has an MPPT capability. So you can have the input for the inverter come directly from a solar panel, in fact the selling feature is that you connect to a solar panel, and the AC end of the inverter goes into an AC socket.
I should mention that these on grid inverters, by law, automatically shut off when the grid power becomes unavailable. So it seems that I would have to work in an off grid inverter to have a continuous power source, a new wrinkle in my plans.
The other feature is the 1000W capability, about ~8Amps at optimum conditions, which for my setup would be sufficient.
Because of the winter weather, at the moment, I have not seen any float conditions with either CC. I generally have to implement a battery charger to keep the batteries from going to low.
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Post by mediadogg on Jan 5, 2020 19:22:55 GMT
Ah, ok. Can you please provide links to where Renogy uses that term, and to the eBay product you are taking about? Any series of words and letters can be used in an internet search. Knowing that the phrase is a search term doesn't tell me what the term means in the context that you are using it.
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raydas
Solar Devotee
Posts: 166
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Post by raydas on Jan 5, 2020 20:05:37 GMT
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raydas
Solar Devotee
Posts: 166
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Post by raydas on Jan 5, 2020 22:00:18 GMT
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Post by mediadogg on Jan 6, 2020 1:12:11 GMT
Ok, I was afraid that was the type of unit you had in mind. You can't legally use such an inverter simply plugged into the AC mains. There is risk of death or injury to power company employees and risk of equipment damage if the inverter and the mains AC signal are not in phase.
The other type of grid-tie invertera (the ones with MPPT) are designed to be installed on the roof as part of your solar panel installation. Each panel (or series / parallel cluster) is connected to its own unit. The AC that they generate is supplied to a common bus regulated by firmware on each grid-tie unit. The bus then feeds a combiner that then runs to special hardware at your service entrance approved by your power company to feed a reversible power meter. All done by licensed electricians.
Now the "Save your pennies" model you referenced is just a regular inverter / charger just like the ones sold by Renogy, at the same price as the eBay one. Amazon sells for a bit cheaper. These units keep the batteries charged from the AC mains and have configuration options that give priority to battery or mains generation supply of AC to the inverter output terminals.
I have seen some of these units with a built-in charge controller, but they usually don't get good reviews and most people already have charge controllers anyway. So, you place the inverter / charger battery terminals in parallel with your existing PV / CC setup, and the AC plug is used both for CHARGING the connected batteries and supplying AC to the inverter output socket. The inverter output socket supplies AC generated by the battery and inverter, or from the mains, depending on an automatic "transfer switch" that is sensitive to whether the mains power is available from the AC plug. So the inverter is NEVER supplying AC to the mains circuits, just to an isolated load. You can find many diagrams and discussions of this on the internet as well as discussion of the dangers and illegal use of the $98 item from eBay.
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raydas
Solar Devotee
Posts: 166
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Post by raydas on Jan 6, 2020 14:56:38 GMT
I will probably be going with the $98 unit on ebay.
Now I am trying to figure out how I will first test the unit out, to get an idea of the functionality. I have, on the work bench, a variable DC power supply, which can provide 24VDC. The first test, if the unit really shuts down when it looses grid power.
Still trying to figure out how I can check the unit for AC output watts/amps. Since I can vary the DC input, I can get an idea of what the watts/amps at the different input voltages would be. Something a little more difficult, how to check the sine wave at the different input voltages. Not sure if I have a device that could produce a load, up to a 1000W, in order to check the $98 unit.
After reading some more of the $98 unit data sheet, I think the get even close to the 1000W rating, the input voltage will probably have to be around 20VDC, but hopefully I can narrow this down, when I do some tests.
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Post by mediadogg on Jan 6, 2020 15:22:03 GMT
Ok, I will say one more thing and then pray for you. Did you notice that the description for the device you want to buy is NOT for that unit? It is for the true grid-tie inverter designed to mounted outside on the PV rack ( they look like this). Compare with the picture of the $98 unit. Do you think it is designed for outdoor use? IMHO, what you are buying is grossly incorrectly described, and might possibly be a scam, if not a mistake. The $98 unit is designed to be plugged into your mains wiring. Good luck even testing it without burning your house down. If your load is isolated from the mains, then you wouldn't need this anyway - a regular inverter will do. It DOES NOT HAVE AC INPUT JUST AC OUTPUT and a sensing circuit on the output terminals to detect when the mains voltage is on. If you think I am wrong, then point out exactly why, and I will humbly apologize. You have nothing to lose if you are correct, but a lot to lose if you are wrong. Description from the listing: THIS IS NOT THE UNIT YOU ARE BUYING!!!! "Smart Microinverter can be easily placed and attached to the rack underneath of PV module. No need spaces for independent installation and low voltage DC wire connects from the PV module to Smart Microinverter can eliminate the risk of high DC voltage. Distributed modularization design philosophy for Smart Microinverterl insures the productiveness of the whole system and will not affect by a single point of failure. Each Smart Microinverter is individually connected to one PV module in the array. Each PV module has the individual Maximum Peak Power Point Tracker (MPPT) control and insures the maximum power is exported to the utility grid regardless of the performance of the other PV modules in the array. When PV modules in the array under non-ideal conditions in practical applications such as PV modules are affected by shading, soiling, orientation, or mismatch, Smart Microinverter insures top performance for maximizes energy production from the whole PV system and gets return on investment in less time." |
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raydas
Solar Devotee
Posts: 166
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Post by raydas on Jan 6, 2020 15:55:00 GMT
That is why I will be testing this thing out on my workbench first. I am sure that I can isolate this test, so I do not "burn the house down".
Amazon sells these units, and they had a few reviews. No review reported a house burning down, or even smoking some wires. But, then again, maybe the ones that had there house burn down, did not, or was unable to write a review. :-)
"Smart Microinverter can be easily placed and attached to the rack underneath of PV module..." I guess they figure this makes the unit weather proof. To me, it looks like the unit should be used inside the house, close to an AC outlet. But that is a hard sell, that means you would have to bring the solar panel wires inside the house. Yes, the description is deceptive. I hope my $98 gamble works out.
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Post by mediadogg on Jan 6, 2020 16:00:55 GMT
That is why I will be testing this thing out on my workbench first. I am sure that I can isolate this test, so I do not "burn the house down". Amazon sells these units, and they had a few reviews. No review reported a house burning down, or even smoking some wires. But, then again, maybe the ones that had there house burn down, did not, or was unable to write a review. :-) "Smart Microinverter can be easily placed and attached to the rack underneath of PV module..." I guess they figure this makes the unit weather proof. To me, it looks like the unit should be used inside the house, close to an AC outlet. But that is a hard sell, that means you would have to bring the solar panel wires inside the house. Yes, the description is deceptive. I hope my $98 gamble works out. The description is just plain wrong. It is for a different unit. And my poetic phrasing about the house was just to dramatize my opinion of the danger. Goodness knows there is certainly enough risk in my own installations that I could not be condescending, just cautious. |
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