sunny boy inverter?

[mudhole]

well it passed the electrical inspection!!!!, power company coming out shortly!! thanks for all the help so far!!

[Ampster]

well it passed the electrical inspection!!!!, power company coming out shortly!! thanks for all the help so far!!

Great news. Keep us informed about how your system performs.

[mudhole]

the power company checked it out and changed out the meter, i commissioned the inverter and it is currently up and working!!!!!!!!!!!!!, thanks for ALL the help on this project. I just need to figure out how to hook it up to my phone or computer, and what the purpose of having it hooked to a computer does for me??

[mudhole]

the highest reading i have got so far is 4.3kw, I bought 18 but due to logistics i only installed 15- 275 watt panels, so obviously the 275 watt is not the max out put of them if i got 4.3kw. what i want to do is buy 3 more panels (same ones), which would give me 6 more to install. my inverter is 5.0Kw rated, so i guess i am overclocking it by about 15% from which i read is very doable.

anyway, i have several options for installing them, it makes it a lot easier if i just tie into the string on the roof rather than running two new pv wires all the way to the inverter (i do have another mppt slot i could use), however if i do , the new 6 panels will be tilted differently...how much will that adversely affect the string?

[Ampster]

the highest reading i have got so far is 4.3kw, I bought 18 but due to logistics i only installed 15- 275 watt panels, so obviously the 275 watt is not the max out put of them if i got 4.3kw. what i want to do is buy 3 more panels (same ones), which would give me 6 more to install. my inverter is 5.0Kw rated, so i guess i am overclocking it by about 15% from which i read is very doable.

anyway, i have several options for installing them, it makes it a lot easier if i just tie into the string on the roof rather than running two new pv wires all the way to the inverter (i do have another mppt slot i could use), however if i do , the new 6 panels will be tilted differently...how much will that adversely affect the string?

My system has a DC to AC ratio of 1.5 to 1 so it is overclocked to the max. Make sure you don't exceed the manufacturers recomendations. Every manufacturer is different.
I think azimuth differences would affect the strings enough where I have seen installations that use different MPPT channels. I honestly don't know the answer about tilt and I don't think PV Watts gets that granular. It is a matter of differences in the relationship of voltage and current that may be affected by tilt. If you have panel level MPPT it would not make a difference.

[inetdog]

My system has a DC to AC ratio of 1.5 to 1 so it is overclocked to the max. Make sure you don't exceed the manufacturers recomendations. Every manufacturer is different.
I think azimuth differences would affect the strings enough where I have seen installations that use different MPPT channels. I honestly don't know the answer about tilt and I don't think PV Watts gets that granular. It is a matter of differences in the relationship of voltage and current that may be affected by tilt. If you have panel level MPPT it would not make a difference.

An experimental paper by SMA shows that as long as the strings are the same length and neither of them have partial shade during their peak production hours there is no need to have separate MPPT channels. The less insolated string will produce less current at its MPP voltage then the higher insolated string, but the VMP values will be close enough that any power loss will be in the low single digits percentage.

[mudhole]

inetdog-"strings are the same length", maybe my definition of string is wrong, but i will have 7 panels that are at 1 position, and 6 at close to but different angle, no shading issues at peak time, but all 13 will be in series creating around 450 peak volts.

[inetdog]

inetdog-"strings are the same length", maybe my definition of string is wrong, but i will have 7 panels that are at 1 position, and 6 at close to but different angle, no shading issues at peak time, but all 13 will be in series creating around 450 peak volts.

Having panels at significantly different angles (either elevation or azimuth) in series in the same string is likely to reduce the available power from the string. This is the sort of situation where either two strings to two MPPT inputs or optimizers on all panels would be considered the proper choice.

The rule of thumb that differences of 5% of less in Vmp (for parallel panels) or Imp (for series panels) when adding a single panel are not likely to cause significant production loss does not apply as strongly when you are talking about two substrings of approximately equal size combined in series.

Are you talking about different azimuth (facing direction) or elevation (roof angle) differences between the two groups of panels? How many degrees in either case?

[mudhole]

would have been a lot easier if i could have got my picture to upload without error!!!, i will give it a try, the array i have set up is facing 190 degrees, with a 10 degree angle , the new site is parallel, but comes off another roof line, which make it landscaped facing 280 degrees at 25 degrees.


i think from what you said, i would be better off using another site, it is the same azimuth and angle, but it gets the sun 1 hour later in the morning and stays sunny 1 hours longer.


probably the best scenario, is to just use the same angle and azimuth roof and just run it on a separate mppt input, it just extends the run to the inverter.

[inetdog]

Yes, that is enough of an angle difference that you do not want to combine then into one series string. If they have the same number of panels and the voltage is high enough, you could put them in parallel into a single MPPT input though.

[nwdiver]

An experimental paper by SMA shows that as long as the strings are the same length and neither of them have partial shade during their peak production hours there is no need to have separate MPPT channels. The less insolated string will produce less current at its MPP voltage then the higher insolated string, but the VMP values will be close enough that any power loss will be in the low single digits percentage.

Are you referring to the 'Shadefix' white paper? That was debunking the idea of module level optimization not independent MPP channels for each string. 'String level optimization' was in the title. I think it is plausible that the losses are minimal if there's no shading but IMO it's worth putting each string on its own MPPT.

[inetdog]

Are you referring to the 'Shadefix' white paper? That was debunking the idea of module level optimization not independent MPP channels for each string. 'String level optimization' was in the title. I think it is plausible that the losses are minimal if there's no shading but IMO it's worth putting each string on its own MPPT.

If the cost is low, independent MPPT channels for each string will also keep problems with one panel from bringing down the output of the array by more than just the direct contribution of the damaged panel.

[mudhole]

i will just put it on the separate mppt input, just a little extra work and cost for pv wire.

I am mad at myself for boxing myself in with just a 5 kw inverter, for just a few hundred extra i could have gone 7 or 10 kw...Here is my thought, if i got micro inverters, how would i tie that into my current set up?, can i just tap the AC out line from my sunnyboy 5.0 inverter?

[nwdiver]

i will just put it on the separate mppt input, just a little extra work and cost for pv wire.

I am mad at myself for boxing myself in with just a 5 kw inverter, for just a few hundred extra i could have gone 7 or 10 kw...Here is my thought, if i got micro inverters, how would i tie that into my current set up?, can i just tap the AC out line from my sunnyboy 5.0 inverter?

How much solar are you trying to install? I have a similar problem with a customer that has a 3.8kW inverter. He started with 4.4kW of solar and expanded to 5.6kW. It would have been worth the $70 to upgrade to a 5kW had I known he would want more but he's only losing ~5% of production from clipping. 7kW on a 5kW inverter would be fine.

[mudhole]

How much solar are you trying to install? I have a similar problem with a customer that has a 3.8kW inverter. He started with 4.4kW of solar and expanded to 5.6kW. It would have been worth the $70 to upgrade to a 5kW had I known he would want more but he's only losing ~5% of production from clipping. 7kW on a 5kW inverter would be fine.

i guess the how much solar answer is ,the most bang for my buck, i guess that would be 10 more 275 panels, that would get me around 7KW. ?

the way our emc meters it is i get roughly $.049 per kw-hr when in excess, i pay $.085 when deficit. so my initial thought was that the most bang for my buck was to get enough panels to offset during the day as much as possible. what i didnt take into affect was the labor to install 5kw is basically the same to run 7kw, and the cost for the last 2kw is cheaper....live and learn i guess

the question about micro inverters was to see logistically how it can be done...i assume i could just tie into the ac out at my ac disconnect.