Opinions on this system design please

[choob]

I can pony up for the MPPT.

Another thing. The best spot for the array, in terms of insolation, is about 130m from the house, which is built in a depression amongst trees.

For the 1500W inverter, I assume 10AWG wire is sufficient if the array is located 130m away?

[SunEagle]

Ok, thanks, that clears things up a bit.

Strange about the grid-tie thing - the manufacturer specifically markets them as off-grid panels. Could be a regional thing? They're locally made for local conditions.

You can use a Grid Tie panel on or off grid. It just means that type of panel has a higher wattage and Vmp rating.

[SunEagle]

I can pony up for the MPPT.

Another thing. The best spot for the array, in terms of insolation, is about 130m from the house, which is built in a depression amongst trees.

For the 1500W inverter, I assume 10AWG wire is sufficient if the array is located 130m away?

I would say that 10AWG is too small unless the voltage is very high.

Depending on what the voltage your array generates you will need to calculate the DC Voltage drop using twice the one way length. That voltage drop needs to be less than 3%.

There is a calculator that will provide wire size based on the voltage and distance being considered.

[choob]

Agreed, what I meant was that the voltage would be 240Vac out of the inverter then a run of 130m of wire to the house. There's a shed up on that hill which can house the equipment.

OK. So, here is the new plan for the system:

1200W array
Tristar 45A MPPT
400Ah battery - 12x 2V batteries in series.

Our sun hours range from a min of 4.5hrs to a max of 9.5hrs. I think the above should be ok?

[SunEagle]

Agreed, what I meant was that the voltage would be 240Vac out of the inverter then a run of 130m of wire to the house. There's a shed up on that hill which can house the equipment.

OK. So, here is the new plan for the system:

1200W array
Tristar 45A MPPT
400Ah battery - 12x 2V batteries in series.

Our sun hours range from a min of 4.5hrs to a max of 9.5hrs. I think the above should be ok?

Even at 240VAC a 130m wire run will need to be much bigger than 10AWG unless your load is less than 5 amps.

And unfortunately there isn't anywhere in the world that gets 9.5 hours of useful sunlight to power a solar panel.

[choob]

Sigh so much misinformation from the solar companies here. There is a website which has accurate sun hour values but can't for the life of me remember or find it.

edit: so according to nasa/larc the range is 5.7 to 7.

edit 2: I've checked a few different calculators and for a 10A load I keep getting 10AWG for 3% loss?

[SunEagle]

Based on where I believe you live you should see an average of 5 insolation sunhours a day all year long. More in the summer then in the winter but when building an off grid system you design around your worst or lowest amount of insolation sunhours. Then if the weather is really bad you have a cushion to recharge your batteries. Also forgot to mention that a generator is a must for an off grid system because you could see more than a few days without sunlight and will not be able to recharge your batteries back in one day.

Sorry, I provided you the incorrect voltage drop percentage. It really needs to be less than 2% not 3%.

[Logan005]

They can still be used off grid, you just need an MPPT CC, they are cheaper than most 12 volts panels

[Sunking]

Battery panels cost 2 to 5 times more than GT panels. With an 80 amp MPPT controller into a 24 volt battery your maximum panel wattage is 2000 watts. With a 80 amp MPPT controller you have the following limitations.

1000 watts @ 12 volt Battery
2000 watts @ 24 volt
4000 watts @ 48 volt
6000 watts @ 60 volt
8000 watt @ 96 volt

Can you spot the pattern? You crossed a line at 1000 watts. 12 volts is for TOYS.

Never Ever under any circumstances use a Prime Number of panels with the exception of 1 and 3. With 5,7, 11, 13... you are screwed.

Under no circumstances use parallel batteries. If you need 630 AH buy 630 AH 2, 4 or 6 volt cells.

[choob]

Anyone know if this is a decent CC? Found local stock.

https://www.victronenergy.com/upload...-100-50-EN.pdf

I also found the morningstar MPPT 45 A which can take a VOC of 150V vs the 100V of the victron. It is over twice the price (650USD vs 300USD)

I understand you want to max the possible voc for the CC, but will the VOC of 126 for the Tristar be significantly better than the 85 for the Victron to justify the price?

The Victron will take 3 strings of 400W while the Tristar will take 2 strings of 600W.

[LETitROLL]

They are both good, won't be much difference in a 24v system, if going up to 48v battery bank then the extra voltage headroom of the morningstar will help some in certain conditions (still not huge though). I have a smaller Victron and love it.

[choob]

Update:

I haven't had time to install everything but I did pull out the PWM CC, wire the 3x200W panels up in series and put in the Tristar MPPT 45.

Fine for a couple days but strange thing happened today, opinions please:

I flipped the battery - CC breaker (63A), can't for the life of me remember why. When I flipped it back on it tripped.

I checked all wiring on battery, inside CC and panels, all ok. Flipped again and it stayed on, CC went through boot up cycle then made a 'snap' sound like a breaker tripping and green LED flashed a few times and it turned off. The morningstar manual is useless when it comes to diagnosing faults via the LED.

This happened a few times, either the breaker tripped or the CC; went outside for a think, came back in and everything turned on and it stayed on. Weird.

Thoughts?

[Sunking]

Disconnect the panels before you connect the batteries.

[choob]

I tried various combinations of things on and off but not sure if I tried that.

Another question:

My inverter has a 240V input. It is also a charger - if supplementing charge with a gen set is it ok to have it charging simultaneously with the solar or will the two CCs not get along? I've had conflicting opinions from everyone.

At the moment I wait until the solar CC stops charging then top up with gen set.

[Mike90250]

.......Another question:
My inverter has a 240V input. It is also a charger - if supplementing charge with a gen set is it ok to have it charging simultaneously with the solar or will the two CCs not get along? I've had conflicting opinions from everyone.....

Read your inverter manual. I won't read it for you. I will tell you my inverter has 2 AC inputs, 1 for Grid and 1 for Generator. The Grid has very tight AC qualification settings for FQ and Voltage. The Gen input has more relaxed settings. If it currently charges from your generator just fine, it's recommended to use the generator in the MORNING to bulk charge the batteries. This is the best use of fuel, fully loading the generator. Then the Solar can finish the charge cycle at the lower absorb and float stages. I too, have several charge sources and they all play well together in a properly engineered system.