Hello everyone,
I have been following the Xantrex forum on this site with talks about grid voltage, but because I have a Sunnyboy SB2500 inverter & 2000W of BP 3160 & 3165 modules in series & grid tie I am asking a question here.
In Australia we are 240Vac & 50Hz & I regularly see 258vac on my Sunnydata Program.
My question is, will my inverter be less efficient trying to push into high grid voltage, especially when my panel dc voltage is down in the morning & evening?
Are they a buck & boost inverter & do you think I should complain to my power company?
We usually like a higher line voltage because welders & the like work better.
I would be greatful of any help on the subject.
Leigh

The Sunnyboy is niether Boost or Buck, its an H-Bridge design. It works by a varing pwm into a BIG transformer ... once at maximum duty cycle, there is no more boost. Boost, is just the ratio of the input to output windings

But the Sunnyboy is limited to it's low line ability, the US version is about 230 VDC when outputing 240 VAC on the SB2500, not sure what the AU design limits are.

Running High on the AC, does increase the minimum DC needed for the unit. So if a US unit is outputing 258AC, then the minimum DC is closer to 250 VDC and this can result in lost harvest.

I'm pretty limited in what is the "norm" with electirc companys, where I have lived the last 11 years is a city owned electric company and they are really on top of things. When I lived in NewEnland, I was't into solar and never really paid any attention to what the grid voltage was, probably like 99.99999 percent of the population

kangaroo,
call the utility and ask them what the accepted voltage limits are. if they give a figure close to or under what you are measuring then ask them to come and check it. i don't know if they'll charge for doing that, but too high of voltage can be dangerous and not just more costly as many appliances aren't meant to safely pass it being higher.

Thanks for your reply Solar Guppy & Niel.
Could I be putting the grid voltage up by the output of my system? The Vac seems to get up around 258 when I'm puting out max 1600W & about 350Vdc.
If the other consumers in the street weren't using much & my house loads are nearly zero & there IS a mains high voltage Transformer 22Kv nearby.
Does the AC work like DC? ie volts = pressure to make the current flow & make the export meter turn ( we are on net metering here)
I don't want to complain to my power company if it is a normal phenomina.
I would appreciate your views.
Leigh

If you have good wiring from your house to the pole & transformer, you should not see much rise, as you push power into the grid.
Another way to check, is shutdown EVERYTHING in your house (that draws more than 10 watts, leave the clock radios plugged in), and measure your voltage (when inverter is NOT running.) Then turn on the cooler, run the fridge, and toaster oven, many of your high load appliances. If you now measure a LOWER voltage, it's an indication of the quality of the wires from the transformer/pole to your entry panel, and you could expect to see the same effect when you push power into the grid, your voltage may rise about the same as you saw it sag.

I see about a 7 volt swing:
Mike

Time VDC DC Amps DC Pwr AC Pwr VAC

6:57:14 341.9 0.02 0 0 239.4
15:25:02 300.6 12.32 3741 3551 246

From working with computers a couple decades ago, Australia was always known for running extremely high line voltages--especially if the place was at the end of a long transmission line (outback).

In general, my specs. for wide voltage power supplies was from 95 to 264 VAC (Japan was typically closer to 100 vac, Australia closer to the 264 VAC--for US, that would be ~100-132vac and 190-264vac as the two expected ranges of voltage that an appliance should operate with).

For anyone, I would call the utility and check what is considered to be abnormal voltages if you have any questions.

For a first approximation, yes, AC and DC voltages follow same basic laws (V=IR, P=I^2 * R, P=V^2 / R). However, AC is much more complicated as there are "phase" relationships between current and voltage. Inductors, transformers, capacitors, etc. behave completely differently when using AC vs DC. Too much to discuss here--but if you want more info, ask and somebody can probably find a website that goes into the basics of AC circuits.

Regarding your electric meter--it does measure "true power" and not just voltage * amps (P=volts*amps is power in DC... But for AC it is P=Volts*Amps*Cos(phase angle) )....

If your inverter is not kicking out from "over voltage" (need to check Australian spec. for Grid Tied inverters too see what they say is unsafe)--then it will be fine. However, if you have appliances and/or lights that burnout quickly then you would want to contact your utility for further details.

In general, 1,600 watts from an inverter is probably not a significant load on your utility line. I=P/V=1,600w/158v=~10amps. If you have a 100 amp main service--that is only 1/10 the current you would expect to draw--so any voltage rise from your inverter would only be 1/10 the voltage drop by your other household loads (electric heat, stove, AC, etc.).

If the inverter is changing your house voltage by more than a volt or two--then your home wiring/utility drop is probably way undersized and/or you have a bad connection some where (corroded or loose connection). And it is something that you would need to look at for safety reasons. (example--a 5 volt increase from your inverter would predict a 50 volt drop when drawing full load of 100 amps--like starting a large Air Conditioning compressor).

Lastly, always remember to check that your volt/amp meter is calibrated and working correctly--Have helped at least one person on a Solar Discussion Group whose meter turned out to have been damaged from earlier usage (over voltage or current spike). The digital meter worked just enough that it seemed to make good readings at lower voltages and currents but was flaky as the readings got higher.

-Bill