Three phase inverter question

[kaneelschep]

Hi all.

I have been always been very interested in reading about solar panels and inverters, and keeping up with whats out there and what it would cost etc.
I also read a lot here, but never posted anything.

We always said that when we would buy a house, that we we would immediately calculate in the price of a solar panel system.
Now it is actually almost this far.
We are looking to go from a rental house in Holland to buying a house in Hungary very soon.

I have never been a person to just buy some deal with some cheap chinese inverter, unbranded panels and man to install them. I want to know exactly what I get and from where. I know a good electricien who can install them. Dont need a company to deliver me all..

Since I own several 3 phase machines like compressor, standing drill, saw table, band saw, welder, I thought it might be a good idea to also go 3fase cooking and that way use less gas/.
And use the sun even more instead of giving back to the grid.
I would just like to use the sun power as much as possible. Like any of you I guess

Through some conctact I can get a sma tripower 20000tlee-10 for a good price.
I read most of the manual and info I can find at sma.
But one thing I could not find.
Can this inverter also give all the power to just once phase?
So if I would for instance be running my washing machine and the other two phases are doing nothing, will it recognize this and give all the power to the one phase instead of always just spreading it over the three phases?
It sounds logical, but can it?

Thanks!

[ButchDeal]

I read most of the manual and info I can find at sma.
But one thing I could not find.
Can this inverter also give all the power to just once phase?
So if I would for instance be running my washing machine and the other two phases are doing nothing, will it recognize this and give all the power to the one phase instead of always just spreading it over the three phases?
It sounds logical, but can it?

That is a grid tie 3 phase inverter. To use it you would need to have a grid feed of 3 phase.
It will not work without the grid either.

It will put out the same power on all three legs but the grid can make up the difference.

[kaneelschep]

From your answer I dont think you actually read all I said, but thanks for the reply anyway.

Since I own several 3 phase machines like compressor, standing drill, saw table, band saw, welder, I thought it might be a good idea to also go 3fase cooking and that way use less gas/.
And use the sun even more instead of giving back to the grid.

So yes. I will need 3phase power. And yes, it will be on grid.

My question was if the inverter instead of always feeding all three phases equally, can feed the phases wich need it the most.

I ask this, because I would put around 3-4kw of panels. Wich lets say gives me 3kw.
And if for instance a washing machine on one phase will be using 2kw. And the other two phases are doing nothing.
I would like it to feed the washing machine-phase the needed 2kw. So It will run for free.
Instead of spreading it equally, so giving the washing machine phase only 1kw and giving the other 2kw back to the grid through to the remaining two phases wich are unused..

Or am I wrong in seeing it this way? Could be. I am very new to this 3 fase thinking. All my reading before was based on 1 phase inverters..

[sensij]

Or am I wrong in seeing it this way? Could be. I am very new to this 3 fase thinking. All my reading before was based on 1 phase inverters..

I'm guessing that where you live, you don't have the favorable net metering terms available to most in the USA. Feed in tariffs are a strong incentive for self consumption of generated power.

With a three phase inverter, equal power is produced on all three legs.

If you put a transformer on the *load*, it might be possible to better distribute the draw of that appliance across all three phases, but it won't be perfect and has both upfront cost and operating efficiency cost.

If most of your loads are single phase, it might be better to go with a single phase inverter and feed a dedicated panel. Although three phase is equipment is powerful, unless that is your profession, you probably aren't operating it enough for the energy cost to be worth offsetting with a three phase inverter.

[adoublee]

With 3-4kW on a 20kW inverter and the relatively low voltage you would probably be at for this 1000VDC inverter, you would also very likely be operating the inverter in a very low efficiency portion of the efficiency curve.

[kaneelschep]

Thanks for the reply.

What I understand of the hungarian system is that the incentive is basicly half of what you pay.
With a promise to use your given back power for free within the year.
The cost of power is actually quite low compared to what i am used to now in Holland.
But I am just trying to come up with a system wich would really maximise the sun usage to our power usage.
Instead of giving too much back to grid and buying it again. It just feels wrong

Thats too bad... I hoped this inverter might have been that smart. sma makes nice machines with a lot of smart add ons to maximize usability..

You are right. Most people would probably be very well off with just 1 phase.
But I do actually like to use those machines more than you would think. Hobbywise working on the house and my cars. And I have them allready. So well..
3 phase is just not that much more expensive per month to have there. Just the initial getting it is a bit costly.
Adding the use of 3phase cooking (also a hobby), to take out the gas usage, it would really make sense to get a 3 phase inverter instead.

I think I am a bit stuck between 1 or 3 phase inverter because of the 'low' panel output.
From 6kw in panels, the question would not be there.
Since that would generate enough per phase to really use the machines on the other phases for free too.
If used and timed with a bit of smartness.

Biggest 1phase loads will be; computers, washer, dishwasher, watercooker, micro, kitchenboiler, oven, waterpump.. The typical.

I can get the sma tripower 20000tlee-10 for the same price as a SMA SB4000TL-21. The 3phase would be used for half a year. And the other new.
both for under 1000 euro.

And with the sma tripower 20000tlee-10 I can always expend the panels later. If I have some extra money.


As I understand it, the Voltage would not be an issue.
SMA SB4000TL-21 for small setups has minimum Voltage of 150V and a starting voltage of 180V. With a best at 400V and a max of 500V.
The sma tripower 20000tlee-10 des exactly the same, just with a best at 600V and max of 1000V.
The amount of possible strings is what really sets it apart.

The 12-14 260wp panels I would add would make around 400V at max. At that, the inverter would still do only 2percent less than at best.

Or I must be reading this wrong. Wich is very possible!


http://energie-unie.nl/wp-content/up...25000TL-30.pdf

[adoublee]

Thanks for the reply.

As I understand it, the Voltage would not be an issue.
SMA SB4000TL-21 for small setups has minimum Voltage of 150V and a starting voltage of 180V. With a best at 400V and a max of 500V.
The sma tripower 20000tlee-10 des exactly the same, just with a best at 600V and max of 1000V.
The amount of possible strings is what really sets it apart.

Maximum power point tracking is not the same between the two - it starts at 320V for the 1000V inverter. What percentage of the time do you think you will clear that?

In the US it is almost unheard of to get 3-phase to the home. In addition, the SMA Tripowers for the US are 480VAC only and most small 3-phase commercial customers are at 208VAC - so we are also having to consider transformers to interface in smaller buildings. If your Tripower is operated at your utilization voltage it might not be a terrible idea for you if you can really get it for the same price. You are just pushing all the boundaries - when you use a product where it is not intended you are more likely to get burned with no support from the manufacturer.

Let us know which way you go.

[Mike90250]

Solar Electric for Induction cooktops (95%), or microwave ovens (60%) is efficient use of power. Hot surface electric cooktop (20%) or hot plate (20%) is not so efficient as you blast a lot of heat away from the food.
There are now Heat Pump electric water heaters for households

[kaneelschep]

I would love a heat exchange pump heating system.. But that is so expensive to install, it is something for the future

It would definetely be induction cooking yes. Hotplates are for students and hot surface is basicly not used here anymore.

At the home I grew up, we always had 3phase power since it was build in 1978. We always cooked electric. My mom still does. But now on induction.
My father was a woodshop teacher in a school with a lot of freedom. So full of machines to play around with between kids building art. Lots of those machines ended up at our house when decommisioned. So we were always welding, drilling, sawing and sanding etc..
3phase is a very normal thing to get here.

In Hungary it is about a 400euro cost to get with paperwork, pulling cables and installing fuseboxes, etc included. But then the extra monthly cost is not much more as having 2x 16/25/35A fuses on a 1phase..

Good you said that!
The mpp range I really did not consider.
I spend some time reading about it now. Something I missed completely before..
That is a very high range for 400V of panels. You would basicly never reach that mpp point unless its summer... So that sais it all I guess.

For now I guess the 1phase is better.
And If I get more panels in the future, the tripower might be a good upgrade.

For some reason I like SMA with the sunny boys. They are a big band here between all the brandless chinese stuff.
But is there something better I should be looking at?

[neweclipse]

For 1 phase starting out and still having ability to upgade later to 3 phase and to also added more solar panels, have a look at Outback Power's line-up.

Outback products are well regarded.

[adoublee]

For some reason I like SMA with the sunny boys. They are a big band here between all the brandless chinese stuff.
But is there something better I should be looking at?

You might consider Fronius as well if you don't need any of the features of module level electronics. SMA has always been good, but week point is probably in monitoring/communications. Their customer service has tanked and they are now coming out with a new line that is essentially "brandless chinese stuff" with their brand name on it.

One thing to keep in mind is you may be able to create three-phase in the future from three single-phase inverters. You might check the capabilities of your selection in this regard before purchasing.

[kaneelschep]

I cant find any outback products here in Holland.. Nothing second hand. Or companies wich use them new. Must be a country thing. Because I had heard abd read of the brand and its reputation.

Fronius I never heard of, but is more represented. Several companies offer them. Also some on the second hand market.
Wich I think sais a lot of how a product is known and used in a country.

I will check their products out!

[ButchDeal]

I cant find any outback products here in Holland.. Nothing second hand. Or companies wich use them new. Must be a country thing. Because I had heard abd read of the brand and its reputation.

Fronius I never heard of, but is more represented. Several companies offer them. Also some on the second hand market.
Wich I think sais a lot of how a product is known and used in a country.

I will check their products out!

Outback makes bimodal (battery) inverters.
most grid tie inverters are not going to balance the legs, they will just dump full and equal power on all legs.