300v system grid tie help

[Mike90250]

I'm going to recommend you get a local professional to help you with this. You might be smart, but you don't know about solar electric power. Info from various people on the internet is not a way to learn about a life changing experience of hooking up a large power generation system to a small 200A panel.

There is a decent book in the the Dummy series about Solar Power for your home, the first version can be found with some searching for a free download on the web, a newer version is in bookstores.

[Ampster]

...........there is also a concern about exceeding the electrical panel bus-bar rating. You may need a line tap or second main panel for that much power. It depends on the electrical panel that you have.

Which is why it is important to know which inverter one is going to use. If we agree that the OP has 10.8kW there may be some cost advantage to going with a smaller inverter so as to not exceed the buss bar rating. There are main panels design for solar but the OP will have to get a knowledgeable person to give him professional advice on that calculation. My guess is it could require as much as a 60 Amp breaker to handle the 40 Amps or more of continuous power output by a 10.8kW inverter.

As Mike suggests, the book is a good idea but beware,, it may also not be up to date on building codes.. That is why professional help is also suggested.

[Woodzykiler]

Which is why it is important to know which inverter one is going to use. If we agree that the OP has 10.8kW there may be some cost advantage to going with a smaller inverter so as to not exceed the buss bar rating. There are main panels design for solar but the OP will have to get a knowledgeable person to give him professional advice on that calculation. My guess is it could require as much as a 60 Amp breaker to handle the 40 Amps or more of continuous power output by a 10.8kW inverter.

As Mike suggests, the book is a good idea but beware,, it may also not be up to date on building codes.. That is why professional help is also suggested.

Again.... 8 Panels in sires it wont be making 10.8kW..... its just not possable

[Ampster]

...........
Im thinking about doing a 8 Series P>P>P>P>P>P>P>P= 256V@ 270W then paralleling 5 of them to keep the 256V but have 1,350W (270Wx5)?

Check your math. Power (Watts) adds whether in series or parallel. You need to get this correct or all your subsequent decisions about inverter size, string size and breaker size will be wrong.

..........Also having a 36V 100AH battery backup with a 5000W inverter for basic backup needs (some kind of switch over?) like some lights, Dvd player and tv. Well thats the idea anyhow..
The idea is to have my panels per-series output 256V Each
Here is a image of my planed layout, subject to changes and advice .....

Okay, now that we have a more complete sense for your system design here is some advice:
As mentioned earlier, figure out what inverter or inverters you will need first. That is going to be a major part of the expense. I do not know of a hybrid inverter inverter that is large enough to handle that much power, so you are probably looking at two inverters. One of those could be a hybrid and the other could be a less expensive grid tie inverter. Some time spent understanding the basics of both will help you make the most cost effective decision.

The other cost is going to be batteries and the most cost effective answer will require some analysis. How much power do you need and how long do you think you will need it? Would you consider a generator if it would save money?

You are probably getting tired of hearing me say this, but my advice and the implicit advice of others is, do not focus on string size at this point. A picture does not help, it only suggests to me that you actually do not want the advice of others or are ignorant or stuborn or some combination. I have no problem helping some one who is ignorant, because that is the benefit of forums like these. If you are stubborn or don't want advice, you are in the wrong place.

[Ampster]

Again.... 8 Panels in sires it wont be making 10.8kW..... its just not possable

Yes 8 panels in series won't be making 10.8kW. The only way it is possible to get 10.8kW of power is to hook up 40 panels in any combination. That could be 40 in series or 40 in parallel or any other combination. It doesn't matter how you wire them, Watts add in any combination, except if they are not connected.

Ohms law and the formula for Watts have been around long enough to be considered immutable. As I have said repeatedly, check your math or clear up my understanding about how many panel you have.

[Woodzykiler]

Check your math. Power (Watts) adds whether in series or parallel. You need to get this correct or all your subsequent decisions about inverter size, string size and breaker size will be wrong.

Okay, now that we have a more complete sense for your system design here is some advice:
As mentioned earlier, figure out what inverter or inverters you will need first. That is going to be a major part of the expense. I do not know of a hybrid inverter inverter that is large enough to handle that much power, so you are probably looking at two inverters. One of those could be a hybrid and the other could be a less expensive grid tie inverter. Some time spent understanding the basics of both will help you make the most cost effective decision.

You are probably getting tired of hearing me say this, but my advice and the implicit advice of others is, do not focus on string size at this point. A picture does not help, it only suggests to me that you actually do not want the advice of others or are ignorant or stuborn or some combination. I have no problem helping some one who is ignorant, because that is the benefit of forums like these. If you are stubborn or don't want advice, you are in the wrong place.

Ok, like i said im very new to solar anything. I have been taking the advice of others here, i watched that video that was posted, then checked the website to see possible choices.
The image was to make sure you guys could understand my layout, Cause i didnt understand how Solar panels would also incress the Wattage no matter what the layout was. it didnt make since to me as i do build Lipo-battery packs for e-bikes. with batterys, is you have a 16S lipo pack you get a higher voltage but not a higher wattage output. so it didnt make since to me.

But you all may be right, based on advice and research from that it seems i will need a inverter per series-string then parallel them at some point, Also did more serching based on avg house hold usage and what i could make on the ideal day, i will be WAY over my own needs. Bring in the money power company i guess? Still i have my smaller 100W test panel here now, i may get a 2nd one and play with it some. I got a MPPT, Deep cycle bat and 750W inverter to play around with.

People i have talked to and on here have told me that MPPT is a better choice them PWN

So if im very wrong and your guys are right (i sure you are) do that mean my setup will be making 257V 10,800W 243A??

[Ampster]

..........
...... Cause i didnt understand how Solar panels would also incress the Wattage no matter what the layout was. it didnt make since to me as i do build Lipo-battery packs for e-bikes. with batterys, is you have a 16S lipo pack you get a higher voltage but not a higher wattage output. so it didnt make since to me.

I have built some e bike packs as well. The explanation of the math is as simple as a small "h". That little "h" is the difference between a Watt and a Watthour (often expressed as Wh). Batteries are storage devices and are often measured in terms of the energy they can store in Watthours. They are also described in terms of the power they can deliver in Watts. The math is different when calculating Watthours then when calculating Watts because you don't add more hours when you add batteries together in series. Does that make sense?

As long as we are talking about batteries, Lipo is a form of Lithium battery that is very energy dense and power dense. That means they can deliver a lot of power instantaneously. That makes them very popular among the RC helicopter crowd. There was a recent story of a fire in a garage in Fairfield California where a guy was charging a bunch of Lipos in his garage for some bike batteries and burned his garage down and injured a bunch of Firefighters. Apparently Lipos can create highly toxic gas when they burn. Apparently the hobby stores sell fireproof bags and the Internet if full of people making Youtube videos of exploding Lipo cells. I do not think that is the case with other safer chemistries like LFP. In the case of batteries it is also important to make subtle distinctions in terms of chemistry. The price point of Lipos may be intriguing but not at the risk of burning down your newly remodeled mobile home and killing people.

But you all may be right, based on advice and research from that it seems i will need a inverter per series-string then parallel them at some point, Also did more serching based on avg house hold usage and what i could make on the ideal day, i will be WAY over my own needs. Bring in the money power company i guess? Still i have my smaller 100W test panel here now, i may get a 2nd one and play with it some. I got a MPPT, Deep cycle bat and 750W inverter to play around with.

Alternatively you could spend some time doing the research so you can speak with conviction about this important calculation. Don't waste your time with another panel. Wire up one or two of your new (used) panels and track the results. By the time you wear out that Deep cycle battery you will be ready to invest in some efficient and safe Lithium batteries. Knowledge is power and checking assumptions is important in exercising that power. It is fundamental to your ability to make progress and to do it safely. Only then can you answer your own question in your last sentence below.

People i have talked to and on here have told me that MPPT is a better choice them PWN

I believe they are a better choice for a number of reasons. They are more efficient and give you more control over charging parameters. That is very important if you want to use the safer Lithium chemistries for your energy storage. All quality hybrid inverters have MPPT circuitry included in them. It is not even a choice when you look at grid tie inverters because of the need for efficiency and to qualify for incentives.

So if im very wrong and your guys are right (i sure you are) do that mean my setup will be making 257V 10,800W 243A??

Only under the best of circumstances and depending on how you wire them. You maybe able to get more voltage and less Amps. That will save you on the cost of wire because you will need less wire diameter the higher you run the voltage. Look at why professionals use strings with higher voltages to reduce the Amps. MPPT circuits probably run more efficiently with higher initial voltages because that may give them more room to find the sweet spot with the greatest power for that instant in time.
Most likely with used panels mounted flat that might only occur on a cold day briefly. However for safety you may need to design for that case. That does not mean that you need to have 10kW of inverters. DC to AC ratios in excess of one to one are common, especially in a case like yours where the panel cost is not the driver. You can find string sizing tools online for most inverters and maximum voltages allowed per string.

[Woodzykiler]

UPDATE: I went and got my deepcycle battery and inverter today. Hooked it all up. Solar pannel, is 16V, 100W. Inverter is Renogy 20A
Its all hooked up but the Solar charger isnt outputting from the panel, panel is outputting power according to my meter, 12.8V, and the battery is at 67% (running this screen and speakers). But the inverter isnt outputting anything from the panel is says. its also very cloudy today. Is it not enough?

[Ampster]

Where is the 12.8 volts that you are measuring? How did you conclude the battery is 67% charged? By voltage or hydrometer?

[Woodzykiler]

Where is the 12.8 volts that you are measuring? How did you conclude the battery is 67% charged? By voltage or hydrometer?

The solar charger controller told me all of this data. Also used my volt meter on the solar panel input. Granted now it seems to be working, a bit slow on this overcast day. the controller says the panel is outputting 12.6V my meter says 12.95V the battery is loseing its charge VERY slowly. but i am powering a TV and speakers. a bright sunny day will tell me more

[Mike90250]

..... Solar panel, is 16V, 100W. Inverter is Renogy 20A.....

First rule Never trust the meters/lights/gauges on the charge controller, They are seldom correct or accurate until you get to the Prosumer grade stuff;

Second rule Kits exist to make money for the seller.

finally, a 16v panel is a really odd voltage and may be intended to directly connect to a battery for charging, Running 16V through a charge controller will not leave enough voltage to charge the battery, which needs 14.5 - 15.5v to charge properly

[Ampster]

Looks like your meters are not calibrated. It is difficult to reach any conclusion with those voltage differences. There may be losses through the controller too. Are you measuring different voltages using the same meter on controller input and output? I don't know what you mean when you say "panel input" unless you mean panel input to the controller?

Other than that it seems to be working with some sunshine. Maybe when the sun is out things will work better. If you had your 40 panels working, you would be getting a lot more power than that 100 Watt panel can deliver.