woelen
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Using microinverter for solar panels as 230 V AC inverter?
I have received a solar panel inverter for free (a WVC-600, intended for use as a microinverter for two 300 Watt panels), but I already have another
good solution for my solar panels.
Is it possible to use such a solar panel inverter as a standalone inverter to 230 V AC, when a battery (appr. 40 V, three lead batteries in series) is
connected to the wires, where normally the solar panels are connected? At the AC-line (which normally is connected to the grid) then one could get 230
V AC?
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Metallophile
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I don't see any reason why this wouldn't work. If it can handle the fluctuating voltage from solar panels, the more steady battery voltage should be
just fine. 600W is not very big, but it could run computers and stuff like that.
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woelen
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How would you have to use that? Normally, the inverter is connected to the AC-grid, but if I want to use it as a generator for 230 V AC, then I simply
do not have to connect it to any AC-grid and simply can connect the load to the AC-output?
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Metallophile
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Oh, I forgot about the grid syncing that these things do. I think you may have found the reason why this won't work.
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violet sin
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The question I see is with the wave matching ability... What's the mains waveform do?
Ive never heard of anyone using a standalone 1-3W wave generator to pump the inverters and get clean usable power... That would lead me to believe
the load effect attempts to drag peaks off cadence or something produced from a logic level signal. Might rely on comparators and mains voltage to
counteract the drift, IDK 100% guess.
If your load was 120% inside the bounds of produced power, battery or solar, would a simple logic level wave work? I'd like to know for sure. These
Random thoughts have been brought to you at the end of the work day, whilst children roam the house... So, to put it another way, not double checked
for clarity, apologies if I've overlooked something
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Twospoons
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There is another potential issue: MPPT (maximum power point tracking). A battery does not look like a PV cell in terms of its I/V curve. This might
make the inverter do some strange things, since it will be hunting for an operating condition that doesn't exist for batteries. If you are really
unlucky you might lose all the magic smoke.
Helicopter: "helico" -> spiral, "pter" -> with wings
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woelen
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If I read this, then I think I simply sell the unit. Such microinverters are quite expensive (prices have exploded the last few months, probably
because everyone seems to buy solar panels, since price of energy have gone up like crazy), so I do not leave it unused around if it cannot be used as
a standalone inverter. Blowing it up in an experiment is too much of a risk with a price tag of nearly 200 euros for the device.
Btw, it is surprising to see that this particular device is around 200 euros in EU-based shops, while it only is around 100 euros on Aliexpress  , sometimes even lower.
Is the device on AliExpress fake/crap stuff? Mine comes from a reputable dutch seller as part of a complete package deal 
In the meantime, I have been reading on how grid tie inverters work and it is amazing to see what is used in such a device. They are quite advanced
pieces of electronics, combined with a lot of math and software. The following is a very interesting read: https://www.instructables.com/Grid-Tie-Inverter/
[Edited on 16-8-22 by woelen]
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Dr.Bob
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The micro-inverter systems are great for if you have a small backup generator, they can help take the load off of it, but most need a "grid" to work,
so you still need a backup generator or UPS and all of the switches to keep your system isolated from the grid during backup use. I hope that one
day each house will have a smart panel that can juggles what loads to run based on the availability of power from multiple sources, and help manage a
backup system that can run or charge off solar, but also work with the grid. Right now you either need a huge battery and inverter system or if not,
grid tied system which are useless in a blackout. Like dying of thirst on a raft in the ocean...
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Organikum
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I am very sure those inverters only sync to the grid when they detect the presence of one and if not they do not stop working but just output the AC
and thats it.
I mean such a device stopping to work by design when you need it most, say the grid failed? Sounds not like a good sales argument, "hey and it has the
feature that when the grid fails you will have no power from solar either!" Microsoft gets away with such things I know.....
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woelen
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Unfortunately you are not right. If the unit is not connected to the grid, then it comes into an error condition (a red LED goes on, powered by the
solar penels), and the AC-output is disconnected from the device. It really has to sync. But I must say, I only did this without a load attached. I
read, however, in the webpage I provided a link for, that a grid tie inverter really tries to sync to the grid sine wave and injects a current to it,
depending on what power the solar panels deliver. The wave form, found on the AC-output, must be within certain bounds (both for amplitude and for
frequency), otherwise it shuts off the AC-output and does not accept power from the solar panels.
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wg48temp9
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My electricity now costs £0.35 per kWhour (including standing charge and tax). I considered PV panels but the feed in tariff is between £0.01 and
£0.037 per kWhour. So I guess I need battery storage and an inverter to save serious money on my electric bill (probably be more than £2.5k a year)
At £0.35 per kW I think it would be cheaper with my own generator using kerosene or even cheaper used cooking oil.
I wonder how hard it is to ferment garden waste to generate methane. It would probably need a huge tank for the digester and an other for storage of
the methane. Easy to run a generator on it though.
Sorry to derail the thread but it seemed vaguely related.
Edit: So petrol at the moment is £1.73 per liter which is about 34.7MJ. 1kWhour is 3.6MJ which means petrol is about £0.17 per kWhour about half
the cost of mains power.
Kerosene is about half the cost of petrol so a kerosene powered generator needs only to be about 25% efficient to cost the same as mains power..
Apparently modern cars are about 40% efficient. I small 2kW generator is probably less efficient say 25%. That's disappointing. I will have check out
PV panels and battery storage.
[Edited on 8/19/2022 by wg48temp9]
I am wg48 but not on my usual pc hence the temp handle.
Thank goodness for Fleming and the fungi.
Old codger' lives matters, wear a mask and help save them.
Be aware of demagoguery, keep your frontal lobes fully engaged.
I don't know who invented mRNA vaccines but they should get a fancy medal and I hope they made a shed load of money from it.
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