Solar Panel with inverter - will it interfere?

[hult]

Yes, but the OP's application is >> 20 amps, so Smarthome's xrp 20-amp filters do not serve the purpose.

my 3kw inverter requires only a 20A breaker, as does the 4kw version (peaks at 17A)

I thought I'd read about a 4.7KW DC source somewhere in this thread for which the 5KW transformer I referenced would be suitable. Maybe it wasn't the OP.

Different breakers have different time-current curves and arc-breakng capabilities, but if the 120VAC power from your converter goes through a 20-amp circuit breaker UL-listed for residential service in US, the _continuous_ circuit current is supposed to be limited to ~2.4KW regardless of the manufacturer's specsmanship.

Is your converter UL listed for residential application? I found that there was/is a very large difference in price between non-listed units and UL-listed inverters

If not, whatever the manufacturer says/recommends/claims may not pertain to those installations where meeting National Electrical Code (if US) must be met in order to stay in conformance with locals rules and regs. That's the vast majority of the population of the US. .

... Marc

 

[damage]

yup UL listed http://www.sma.de/en_US/products/grid-tied...us-4000-us.html

 

[hult]

yup UL listed http://www.sma.de/en_US/products/grid-tied...us-4000-us.html

Those guys be ~250-350 VDC input! My converter runs off batteries from my 1967 Electric VW bug which is designed to handle up to nominal 144vdc (3 x 48vdc banks) and is for backup purposes.

300 volts would burn up my 60v inverter right quick. I'm quite certain I don't want to mess with a 300vdc battery pack either .... I'd have to keep _both_ hands in my pockets ;-)

How is 120VAC derived from the ~240VAC output?

... Marc

 

[BraveSirRobbin]

Guys, I might be getting confused here, why the high voltage inverters when using solar panels?

 

[damage]

Guys, I might be getting confused here, why the high voltage inverters when using solar panels?

i'm guessing it has to do with the panels being wired in series in "strings" to the inverter. higher voltage, lower current, thinner wires = easier to wire.

 

[hult]

Guys, I might be getting confused here, why the high voltage inverters when using solar panels?

i'm guessing it has to do with the panels being wired in series in "strings" to the inverter. higher voltage, lower current, thinner wires = easier to wire.

Also: Reduced electronics cost

Also: Increased overall efficiency ; (Vout * Aout) /(Vin * Ain ) *100%

The bandgap voltage drop across a semiconductor junction is nearly constant, so the higher the rail-to-rail voltage of the system, the smaller the bandgap voltage drop is as percent of total, so the higher the overall % system efficiency.

This in turn reduces waste heat, which reduces required heat sink and overall package size and complexity.

Moreover it is generally less expensive to increase wattage by increasing voltage than by increasiing current -- typically almost up to the state-of-the art of semiconductor voltage limits (for a given device family) which have crept up steadily over the decades.

... Marc

 

[hult]

Have an electrician filter your inverters
after your inverters and before your electric panel.
use fuseable links with xpf filters.
xpf filters are rated at 20 amps.
I wired in 15 amp in line fuses and then a filter on each power leg and put it all in a 12x12x6 nema 3r can.

Solving x-10 problems and making old systems work is easy.

Might you mean like this?

( I would *not* wire in-line fuses. IMO/E much better to use external circuit breakers for several compelling reasons.)

D

Underneath the filters are the mechnical 12vdc, normally open relays that provide air-gap isolation of the two 120VAC legs and the normally closed solid state relays that are control by low voltage, low-current signal ( eg 5-12vdc) .This is to be able to disconnect sensitive equipment from the AC line. This lower "layer" of the equipment in the box is shown in the photo below.

Also visible outside the box is 120VAC+120VAC surge protector.

There are two Corcom noise filters stacked one on top of the other that provide broad-band noise reduction.

The plastic case with RJ45 connector in the top center will be replaced with a WebControl which will also control the 12vdc relays, monitor the output of current transformers (not shown) and provide input for a local, manual overide.


Also visit http://www.econtrol.org/power_conditioning.htm

My web site is, alas, years out of date.

... Marc

 

[SteveQ]

I am also confused about the use of such high voltages in solar panels. I have done a fair amount of research over the past years and all the panels I see are typically 24V.

Are panels that output 250-350VDC actually available? Are they safe? How can you install them and work with them?

Steve Q

 

[damage]

I am also confused about the use of such high voltages in solar panels. I have done a fair amount of research over the past years and all the panels I see are typically 24V.

Are panels that output 250-350VDC actually available? Are they safe? How can you install them and work with them?

Steve Q

the panels are not high voltage. they are wired in series to the inverter & each panel in series adds to the voltage at the inverter.

 

[SteveQ]

Thanks, I understand that voltage is additive, but I'm not sure I understand the design concept. For residential systems that are typically roof mounted, it is my understanding that panels are connected together on the roof. So if a large system has 10 panels. it would be a wiring nightmare to run a wire from each panel so they could be interconnected at the inverter! Maybe these high voltage inverters are designed for special applications where the panel to inverter distance is really short. ie not residential use.

Steve Q

 

[damage]

Thanks, I understand that voltage is additive, but I'm not sure I understand the design concept. For residential systems that are typically roof mounted, it is my understanding that panels are connected together on the roof. So if a large system has 10 panels. it would be a wiring nightmare to run a wire from each panel so they could be interconnected at the inverter! Maybe these high voltage inverters are designed for special applications where the panel to inverter distance is really short. ie not residential use.

Steve Q

what you are talking about is wiring in parallel. the standard way panels are wired is in series. the negative of one panel is connected to the positive of an adjacent/nearby panel. the panel at the beginning of the run & the one at the end will each have an unconnected terminal, there will be one + and one - left unconnected. those 2 are run to the inverter along with a ground wire.

 

[bpwwer]

Thanks, I understand that voltage is additive, but I'm not sure I understand the design concept. For residential systems that are typically roof mounted, it is my understanding that panels are connected together on the roof. So if a large system has 10 panels. it would be a wiring nightmare to run a wire from each panel so they could be interconnected at the inverter! Maybe these high voltage inverters are designed for special applications where the panel to inverter distance is really short. ie not residential use.

Steve Q

I have a typical residential roof mount system. The panels on the roof are split into 3 "strings". Each string is composed of 13 panels wired in series. 6 wires run from the roof to the inverter, 1 pair for each string. I think the voltage of each string is around 370vdc (no load). Not something I want to mess with!

 

[priorityelectric]

Thanks, I understand that voltage is additive, but I'm not sure I understand the design concept. For residential systems that are typically roof mounted, it is my understanding that panels are connected together on the roof. So if a large system has 10 panels. it would be a wiring nightmare to run a wire from each panel so they could be interconnected at the inverter! Maybe these high voltage inverters are designed for special applications where the panel to inverter distance is really short. ie not residential use.

Steve Q

I have a typical residential roof mount system. The panels on the roof are split into 3 "strings". Each string is composed of 13 panels wired in series. 6 wires run from the roof to the inverter, 1 pair for each string. I think the voltage of each string is around 370vdc (no load). Not something I want to mess with!

The panels wire into the inverters and then to the electrical panel.
in between the inverters and the electric panel there should be a disconnect.
The proper location for the filter would be between the disconnect and the panel, thus being able to work on it with power off. Turn disconnect off and break off. Be sure to have a licensed electrician do the work.

 

[SteveQ]

Thanks, I understand that voltage is additive, but I'm not sure I understand the design concept. For residential systems that are typically roof mounted, it is my understanding that panels are connected together on the roof. So if a large system has 10 panels. it would be a wiring nightmare to run a wire from each panel so they could be interconnected at the inverter! Maybe these high voltage inverters are designed for special applications where the panel to inverter distance is really short. ie not residential use.

Steve Q

what you are talking about is wiring in parallel. the standard way panels are wired is in series. the negative of one panel is connected to the positive of an adjacent/nearby panel. the panel at the beginning of the run & the one at the end will each have an unconnected terminal, there will be one + and one - left unconnected. those 2 are run to the inverter along with a ground wire.

Thanks, I just always assumed the common way that panels were wired was in parallel because of safety concerns. Now I understand why there is so much emphasis on permits, inspection, and licensed installers. I would not want to be the guy on the roof who has to make the connection of a string of 10 panels to the wire pair that goes to the inverter! Where do they put the disconnect switch? I assume it has to be accessible so it's not on the roof.

Steve Q

 

[damage]

Thanks, I just always assumed the common way that panels were wired was in parallel because of safety concerns. Now I understand why there is so much emphasis on permits, inspection, and licensed installers. I would not want to be the guy on the roof who has to make the connection of a string of 10 panels to the wire
pair that goes to the inverter! Where do they put the disconnect switch? I assume it has to be accessible so it's not on the roof.

Steve Q

the disconnect is either right next to the inverter or built into it. some jurisdictions require a rooftop disconnect as well.

you don't need licensed installers. i volunteer for a non-profit that provides low cost solar installs (on the backs of volunteer labor). we recently installed a 15 panel, single string, 3kw system. final interconnection is done by the one guy who runs the non-profit (who is a licensed installer). and of course everything was inspected by the city (and triple checked by the licensed installer).