new on solar energy

Re: new on solar energy

voyager wrote: »

I am not sure if the 12 AWG 4 wire cable, supports 50 Amps. Do you know if it is OK?

No, 12 AWG will (typically) only support ~20 amps maximum (US NEC)... I do not know what is "legal" in Mexico.

Using the US NEC, pretty much the minimum to support ~50 amp breaker, you would need 8 AWG wire (there are insulation, temperature, and conduit fill factors too--If you are following the NEC):

https://lugsdirect.com/WireCurrentAmpacitiesNEC-Table-301-16.htm

I know that the main panel, supports 120 VAC and 220VAC but I am not sure if it supports the 900 Watts or 2500Watts of the inverter.Tomorrow, will accompany me during installation, an electrician specialist. I will ask him if the main panel of my house support 900Watts / 2500 Watts and 30 Amps of the inverter.

The main panel--There are several "rules" that need to be followed (in the US). First one, is what is the box rated in terms of supported circuit breakers. Usually, 15 amp would be the minimum that any current box would support--And they can go much larger.

The second--Again in the US, there is the maximum current you are allowed to put on the main bus bars. We would use 120% of the bus bar/box rating.

Say your box is rated for 125 amp main breaker+bus bars. The 120% rating would be:

125 Amps * 1.20 = 150 Amps total

Then the maximum GT Inverter branch circuit would be:

150 Amps total - 125 Amp main breaker = 25 amp maximum GT branch circuit.

You can also (in some cases) derate the Main Breaker:

150 Amp total - 100 Amp main breaker = 50 amp maximum GT branch circuit.

And then there is where to install the GT branch breaker(s)... If the Main breaker is at the "top" of the bus bars--Then the GT branch circuit breaker(s) should be installed at the "bottom" end of the bus bars (opposite end of bus bars from main breaker).

Note--Your GT inverter is 110 VAC output--So, if you have 120/240 VAC split phase power (typical North American service), you could put a (for example) 25 Amp 110 VAC breaker on the "black" phase and a second 25 Amp breaker on the "red" phase. Or you could put a pair of 25 amp breakers if your GT inverter had 220 VAC output.

The inverter manual says:

AC Output Power: 2500 Watts
AC Output Voltage Range: 110V ~ 120V
AC Output Frequency range: 60 hz for 110V
Total Harmonic Distortion (THD): <5%
Power Factor: 0.99
DC Input voltage range: Marked 28V ~ 48V
Output Current Waveform: Pure Sine-Wave
MPPT Function: Yes
Over Current Waveform: Yes
Over Temperature Protection: Yes
Reverse Polarity Protection: Yes
Island Protection: Yes
Stackable: Yes
Maximum temperature range: -10°C ~ 65°C
Normal temperature range: 0°C ~ 40°C
Storage temperature range: -15°C ~ 75°C

There should be a Maximum Amperage output rating for the GT inverter too (something like 28 Amps maximum at 110 VAC).

-Bill

Re: new on solar energy

ore

voyager wrote: »

Hi Bill, I just wanted to inform you that the panels are working properly. I have seen no variation in the amount of power being generated. We have had days of heavy rain and strong winds, and the panels have remained stable.

Panel voltage will remain about constant at Vmp (once you have minimal direct sunlight)--And will vary with temperature (cold, higher Vmp-array, etc.). Assuming the MPPT function of your GT inverter is working correctly.

Something that caught my attention was that last week we did not have service from the electric company by a problem in the area.

I thought, that the solar panels will continue giving energy to the house. And this was not the case, since the inverter stopped working until the service was reactivated by the electricity company. From what I understand, the inverter requires to have service of the electricity company to function.

The GT inverter will attempt to hold Vmp-array steady while varying Imp-array to keep Vmp stable (i.e., if Vmp starts falling, the GT inverter will dial back on the current a little bit).

So--Power=Vmp*Imp or really Power= Vmp * Ipanel based on amount of sun.

The second 1/2, of the issue is that a GT Inverter's 120 VAC output is "in parallel" with the 120 VAC utility power.... Very much like your alternator for the car is in parallel with the car's lead acid battery. The lead acid battery holds ~12vdc, and the alternator adds current to keep the (charging voltage of the battery). If the 12 volt battery bank "goes near dead", the alternator cannot generate enough voltage/current to keep the battery bus at 12 volts.

Pretty much how the GT inverter works. It looks for 120 VAC +/- ~10%... If the line voltage falls too much, or goes too high (or the 60 Hz frequency goes out by +0.5 Hz or more), the GT inverter will shut down to prevent electrocution (line men) and/or giving low voltage (brown out) to the appliances (in reality, a GT inverter is not designed to regulate to 120 VAC at 60 Hz, it only "follows" the voltage/frequency set by the much larger AC utility generators). A "small" GT inverter could never supply enough current/power to run the home, let alone the rest of the neighborhood.

Can you explain me, what I have to do to use electricity from the solar panels even when we do not have service of the electricity company? I am interested that inverter remains with the same function to be "grid tie".

More or less, you have two options. One is the traditional Off Grid AC inverter and battery bank. The Solar panels + charge controller provide energy to the battery bank, which the Off Grid inverter uses to produce 120 VAC @ 60 Hz power to run your home. You cannot connect an Off Grid AC inverter directly the to the grid and share (feed back power) back to the grid.

The second option is a "Hybrid" AC inverter... It combines the function of a standard AC Inverter+Charger and the battery bank+solar panels+solar charger (as above). You connect:

AC mains to AC1 input on the Inverter+charger+internal AC transfer switch and both to the DC battery bank and an AC sub-panel.

When the AC mains are "up", the AC power goes through the inverter to the sub-panel to power your loads. The inverter+charger can charge the battery bank (like a UPS). And, the Hybrid inverter can take "excess battery charging current" (when batteries are full) and dump that power to the grid (i.e., the AC inverter uses the grid like a dump load).

When the AC mains fail, the AC Transfer switch fails and the Hybrid Inverter turns into an "Off Grid" AC inverter powering your sub-panel from the battery bank.

There are several types of Hybrid inverters with various AC and AC generator inputs, GT capability, and other capabilities.

The problem is that if your AC mains power is relatively stable with few outages (and outages that last less than 1-2 weeks), a backup genset+GT Solar is better than going with a Hybrid Inverter + Battery bank (and still should have a backup up genset too--for bad weather and 2nd AC backup power).

In general, GT Inverter+Solar panels + backup genset + stored fuel (or natural gas, etc.) is usually more cost effective. The large battery bank needs replacing every 3-8+ years--Depending on battery quality, maintenance, type, how much is is used, etc.

-Bill