It sounds to me as if most of the installed systems for residential solar power are wired in parallel, is this correct? If so, is it fairly easy to add new modules to a system? I'm wondering what kind of connectors are usually on the panels and if they are sort-of "plug and play."

Thanks in advance!

Actually wiring depends on the inverter used.

Systems like the Xantrex SunTie, SW series and Outback FX units are designed to run in the ~48V range. These tend to use sets of 1-4 panels wired in parallel depending on panel voltage. These can be grid tie or off grid with battery/generator backup.

Other systems like the SMA Sunny Boy and Fronius IG series use series wired panels in the 150-400VDC range (sets of 4-20+ panels). These are grid tie systems.

Most common connector is the MC connector. It makes series connections plug and play for the most part. Parallel can be bit more complex.

Main concern when adding panels is system capacity. Excess panels will be wasted if the system doesn't have the capacity to do something with the power.

Sean

I was considering going with the Sunnyboy and a grid-tie system. I was also probably going to use the Sanyo HIP-J54BA2 (180 Watt) panels. Seeing as those put out about 54 Volts at 3.33 Amps. Assuming the SB handles up to 2500 watts and up to 400 Volts, then the most panels (of the type specified) that I could attach wound be 7 panels in series. Am I correct in assuming that (P=IV) and that the SB can handle at most, 6.25 Amps? If so, I'd have to get different panels to wire in parallel with the 7 Sanyo panels to keep the Amps below 6.25 (i.e. in parallel, you add amps, in series, you add voltage -- or did I just mess that up ).

Thanks again,
Dave

My bad.

Unless I read the spec wrong, the DC input voltage is 250-600VDC and 13 Amps. The advertised best range for input power was listed as 2750W to 3450W so I guess I'd be ok putting in two strings of the Sanyo panels connected in parallel. Granted, I can't actually afford that large of a system... yet, but I'm hoping to start off with 8 panels.

Check out the string sizing program SMA has on their site at http://www.sma-america.com/index.asp that wil tell you how many modules you can use and how many series strings.

Speacock:
> Other systems like the SMA Sunny Boy and Fronius IG series use series
> wired panels in the 150-400VDC range (sets of 4-20+ panels). These are
> grid tie systems.

> Most common connector is the MC connector. It makes series connections
> plug and play for the most part. Parallel can be bit more complex.

Just finished working on a nice little grid tie, using a pair of Fronius IG inverters. 44 x 123 watt panels (Sharp), four banks of eleven in series. 220-odd open circuit volts at the end of each string, then two strings in parallel, into each Fronius IG. Nice little inverter, that. VERY light, very nice and easy to wire up. Then the 240AC from each Fronius IG back into the AC breakers (as per the project engineer's wishes).

Very slick.

And sadly. up here, we're not allowed to use the "cool" connectors. Just wires under the clamps...

DJ

That either seem low or high for the Fronius (150-450VDC). 220 VOC is going to be getting really close to the 150 minimum (I calcualte 151 volts in my heat for mppt) or if you mean 440 VOC (series) your gonig to exceed tha maximum input voltage when cold.

BTW , I have a PV power and Fronius on the way I'll be testing for the next few months ... Have a garge full of lab equipment to do very indepth and detailed testing with

Please keep us posted. Due to my panels being backordered I may still change inverters based upon your testing.

Sean

Guppy:
> That either seem low or high for the Fronius (150-450VDC). 220 VOC is
> going to be getting really close to the 150 minimum (I calcualte 151 volts in
> my heat for mppt) or if you mean 440 VOC (series) your going to exceed
> the maximum input voltage when cold.

Then very close to the minimum, yep, by your count. A Sharp 123 data sheet I've seen, though:
http://www.wholesalesolar.com/pdf.folde ... rp_123.pdf
says that the math would be 17.2 x 11, giving 189.2v, which would be better, then? And please, Gup, if I'm getting that wrong, correct me! I'm in this business to LEARN!

And if it *is* closer to your numbers, well, what can I tell ya. Designed by an engineering outfit; I was just lead monkey . I *was* the guy on the roof doing the last wire check, and each bank *was* 220-230 odd volts, open circuit... and to make sure I am using the right term, that's checking the pos at one end and the neg at the other with a volt meter, no load.
Then two banks in paralell, and each pair of banks into a separate Fronius IG. And then each Fronius into an AC breaker with lightning arrestors in parallel.

Apparently, it's been started since, and ran fine. But I will enquire!

DJ

The 17.2 value is when the panels are at 25C ... on the the roof they are much hotter and the 17.2 falls 0.45% with every "C" above 25C the panels get

Here in Florida , tempatures in the Summer are in the mid 90's , hot , but not as hot as parts of CA and of course the desert NW.

Right now , the mppt's of my roof arrays adjusted for comparison are just a hair over 14 volts , (they are 17.2 as well for 25C) ... this would put a string of 11 at 154 volts ... right at the bottom of the minimum operational input for the Fronius

If your getting above 93 degrees , or the roof is a dark color this is system will under perform because the inverter won't track below 150 volts.

I'll be running some extensive tests on the IG3000 soon ... I plan on running 8 pw-16500-155's in a string , two srings in parallel , for an mppt of about 230 volts ...

Where is this installation located ?

I'm not sure what "running fine" means ... most folks wouldn't know if the system is sub-par performance ... just go to th site mid-afternoon on a hot day and see what the array voltage reported by the inverter is , if it with a few volts of 150 , theres performance being lost

If I was the "enngineering outfit" I wouldn't go lower than 12 panels in a string with the sharps ...