new on solar energy

Re: new on solar energy

What are you looking to do?

1) Run solar panels to GT inverter to your main panel and feed power to your home/backwards to the grid?
2) Run solar panels to battery bank to an Off Grid AC inverter so you can run AC power without the grid?
3) Same as #2, but using a Hybrid Inverter that can do both GT and Off Grid power?

Do you have 120 VAC only Utility power, or do you have 120/240 VAC split phase power (typical North American utility power)?

The two inverters you linked to are Off Grid AC inverters (option #2)... One is a Sine Wave inverter (usually a better inverter but more expensive and slightly less efficient). Vs a Modified Square Wave inverter. Cheaper, sometimes a bit more efficient, but MSW waveform is less than ideal for motors (like your refrigerator, well pump) and many electronics with small transformers (wall mount, in-cord) and some AC power supplies (which can overheat/fail).

Are you trying to save money on your power bill? Then a Grid Tied system (solar panels > GT Inverter > main panel+utility power) is the better choice. You will not have emergency/backup solar power unless you install a backup AC generator.

If you are trying to "off the grid"--Then you need a battery bank and off grid AC inverter. Usually costs a lot more for power because of the battery bank (replace batteries every ~5-7 years or so) and other reasons (less efficient so need more panel, more losses for "extra" energy conversion, etc.). In the US, typically off grid power will cost ~$1-$2+ per kWH. If you get really good deals on the equipment and are careful how you run your system, you may get below ~$0.50 per kWH (you are in a sunny region--will help reduce costs).

If you want both AS Mains power plus emergency backup power--You need to add batteries and a hybrid AC inverter. Not cheap, but power costs can be less because you still have AC mains.

-Bill

Re: new on solar energy

All we need to know is that you have 120/240 VAC 60 Hz split phase utility power... So you can use either 120 or 240 VAC GT inverters. It does not matter if your appliances are 120 or 240 or a mix of them. The utility meter will keep track of the kWH usage just fine.

You need to look for a Grid Tied inverter. All of the ones you pointed at are Off Grid inverters that are designed to connect to a battery bank and power AC loads directly (no grid/utility power involved). The solar panels would recharge the battery bank during the day.

Searching for solar grid tie inverters on Amazon will give you a bunch of "low end" GT inverters. Click through a few of them and see what they are.

In general, we would suggest better quality units like these (and others) that are NRTL (UL and others) Listed:

http://www.solar-electric.com/gridtiesolar.html

Note--On the above link, there are "Hybrid" GT/OG inverters that are capable of both functions and require a battery bank (pure GT no-battery vs Hybrid system).

You might look through this thread too--I tried to explain the inverter world in one post:

battery-less Outback Radian (GT/Off Grid/Hybdrid Inverter options explained)

The subject does start out simple--But quickly expands into all sorts of options/different methods to address a customer's needs and leads you down a rabbit hole very quickly.

-Bill

Re: new on solar energy

voyager wrote: »

Thank you Bill. I selected the following options of low end solar grid tie inverters:

I will be waiting to have the following characteristic in each panel (72 cells - 6"x6" - Mono - 4.2 Watts per cell):
- Maximum Power a t S T C ( P m a x ): 300 Watts
- Optimum Operating Voltage (Vmp): 37.46 Volts
- Optimum Operating Current (Imp): 8.01 A
- Open-Circuit Voltage (Voc): 46.12 Volts
- Short-Circuit Current (Isc): 8.56A

I finally did a selection of low end solar grid tie inverters. But I will appreciate if you can review if they work with my panels: I select 2x1200 Watts, 2x2500 Watts, 2x3500 Watts but I can not understand the difference between the characteristic of "Charge For 24V DC (36V Vmp)/ 36V / 24V / 36V Solar Panel" to take a decision.

The "pairs" of GT AC inverters you have listed are identical, as far as I can tell. They are the same product just sold by two different vendors. The descriptions are written (probably) by a non-English speaker--So a little awkward.

2500 Watt Grid Tie Power Inverter 28 V-52 V Dc Input / 90 V-130 V Ac Output Charge for 24 V Dc (36 Vmp) Solar Panel System
2500 Watt Grid Tie Power Inverter 28 V-52 V Dc Input / 90 V-130 V Ac Output Charge for 36 V Solar Panel System

The DC input operating range for the inverters is 28V-52V DC Input, with the "optimum" Solar panel voltage at Vmp~36 VDC (STC). For the 1,200 Watt gt inverter, you would have ~2-4 panels in parallel (note, more than 3 panels connected in series, each should have a ~15 amp fuse or circuit breaker to reduce the chances of solar panel/wiring fire if there is a short circuit in your array).

There is no "charging" going on with the GT inverter. There is no battery bank needed. However, if you wanted to use batteries for some reason, the inverters appear to be designed to work off a 24 volt battery bank (usually fed by solar panels, wind/water turbines, etc.). Basically, when the battery bank is >28 volts, the batteries are charging and there is probably excess current that can be "sold to the grid" like a diversion load/GT inverter.

Because of the technically unclear English (I believe), it makes it a bit difficult to understand how all of this works together (I don't speak/write in any other language--So I could not even do a fraction of this writing outside of English, technical or otherwise).

I have a basic question: If I installed all the solar system kit including the inverter, where I am going to connect the inverter? I am going to connect the inverter to any electrical outlet in the wall of my house? or I need to connect directly to the main panel of the house?

Note--You are approaching the point that those folks like me who try to help new folks to solar, like you, dread.

I can (and will) give you as much help as I can--But configuring/installing Solar GT systems on a home without detailed knowledge is dangerous. You are working with relatively high voltages and power levels. And you are adding local power generation to your home's power system which, if done incorrectly, can easily cause a fire or worse.

To understand--You setup up an array of solar panels (Vmp-array ~ 36 volts, or your 72 cells in series) and parallel them to meet the input voltage/current range needed by the GT inverter.

For a 1,200 watt GT inverter, you would take ~2-4 of your 300 Watt solar panels, wire them in parallel. And if more than 2 parallel strings, you should put a 15 amp breaker/fuse in the + lead of each solar panel to reduce the chance of a short circuit causing a panel/wiring fires.

Of course, your panels need to have heavy enough cabling, copper bonding tape, bypass diodes that can withstand >15 amps of current before they overheat and fail.

The voltage/current from that array then is connected to the DC input of the GT inverter.

The output of the GT inverter would (ideally) be connected to a 15-20 Amp branch circuit from your main panel. Some people just plug the GT inverter into a 120 VAC outlet--But for various reasons, it is saver to add a new 15 amp circuit breaker to your main panel and run a Hot/Neutral/Ground branch circuit to your AC inverter. This new branch circuit would conform to your local code (ROMEX, Conduit, Knob and Tube, etc.). Your Main AC panel also needs to be rated large enough to properly receive the 120 VAC 1,200 watts from the GT inverter... A lot more detailed discussion needed here to understand how to safely connect everything.

Another question: Is it correct to install the inverter inside my house in the wall? or you have your inverter outside your house?

This GT inverter does not appear to be weather proof (the ones I linked to on our host's website are weather proof). So, you cannot mount these Power Jack units out side in the weather. You would need to mount them somewhere they get good ventilation.

Power Jack units are known for overheating if operated anywhere near their rated capacity. That is a fire hazard, so these inverters should not be bolted to a wooden wall or over a wooden/flammable floor.

I'm cutting aluminum frames to build bases and panels. I'll be commenting as my experiment progresses.

Note that glass and aluminum have vastly different expansion rates (panels are exposed to sub freezing temperatures at night and upwards of 180C during noon-time summer sun).

Solar cells have a coefficient of expansion much closer to that of glass--So make sure your aluminum backing/frames are not bonded to the cells.

One last warning. Your solar panels are going to fail--Probably in a few months. And they can fail shorted, open, or arcing connections. DC current (over ~12 volts) strikes and sustain arcs very nicely (think of your solar panels+wiring as a very nice and small potential arc welder). The chances that there will be hot spots/arcs in your panels is very high (and possible short circuits to the metal backing--if you really are using metal backing). Do not install these panels anywhere flaming debris, falling electrical cabling, etc. can light brush or buildings on fire.

The Power Jack inverters are also of questionable quality. You should keep them away from wood/plastic/etc. building materials. Thy will need lots of free air for ventilation, so you would not build these "in the wall" (that may be an error in English--I would say mounting them "on" the wall--A non-flammable wall).

Good Luck,

-Bill