Please help - Solar panels

[Mig54]

Hello Everyone- Newb from South America.

I would appreciate if someone could help me with calculating the number of solar panels I need for my off grid system. I recently I bought a MPP Solar inverter model PIP 8048Max 48V MPPT, and I am in the process of buying the panel and batteries, I calculated my daily use of power at 20 KW. The spec for the inverter is the following:

- Rated power 8000VA/8000W

- Nominal output voltage 230VAC

- Frequency range 60Hz

- Efficiency peak 93%

- No of load power consumption <70W

Solar charger & AC Charger

- Max PV array power 8000W

- PV inputs 2

- Recommended Min. PV input 100 VDC

- Max. PV input current 18A each

- Max PV array Voc 500 VDC

- Max. solar charge current 120A

- PV array mppt voltage range 90Vdc – 450Vdc

- Start-up voltage 80V +/- 5Vdc

I am planning to buy Trina Solar panels 500W, reading the specs I got confused with the STG and NMOT data, I never done a PV system. The info I got from the data sheet for NMOT is:

- Max power – Pmax 379WP

- Max power voltage 40.4V

- Max. power current 9.37A

- Open circuit current ISC 9.89A

And the batteries, they will be 4 Pylontech US5000, 48V

- Nominal capacity 4800

- DOD 95

- Usable capacity (Wh) 4560

- Discharge voltage 44.5 – 53.5

- Charge voltage 52.5 – 53.5

I want to start with 4 batteries, and I would like to know how many panels I need. I live in a remote part of Peru, and I don´t have many options. I never done any PV system before, my house currently use a generator, but it is too noise and my wife complains about it. We use to live in Los Angeles, retired and decided to buy a piece of land here. It is beautiful, clean and quiet, but sometimes we miss the Good Old USA.



Thank you very much for reading my post, and thank you for helping those who want to learn DIY.



God bless you.

 

[sunshine_eggo]

Need panel STC values.

 

[BentleyJ]

Thanks for posting all that information There is one other piece of the puzzle that would really be helpful. Azimuth and tilt of the panels as well as how much roof or ground mount area you have available.

To give you a rough rough idea, if you are looking to produce 20kWh per day then 10 to 12 of those 500W panels would be an estimate. Unless for some reason there is a lot of shading, frequent cloud cover or the panels are pointed at a non ideal angle then more would be needed.

 

[Mig54]

Thanks for posting all that information There is one other piece of the puzzle that would really be helpful. Azimuth and tilt of the panels as well as how much roof or ground mount area you have available.

To give you a rough rough idea, if you are looking to produce 20kWh per day then 10 to 12 of those 500W panels would be an estimate. Unless for some reason there is a lot of shading, frequent cloud cover or the panels are pointed at a non ideal angle then more would be needed.

Hi Bentley,
Thank you for responding to my post. The tilt of the panels is only 12 degrees. I have plenty of space and no shaded area. The panels will be mounted on a metal structure 6-7 feet above ground. The location is in the middle of Peru, with 5 peak sun hours and facing North. Thank you and take care.

 

[Mig54]

Need panel STC values.

Hi sunshine,
The STC info is:
Max Pmax 500W, max power voltage 42.8, max power current 11.69, voc 51.7, and ISC 12.28.
Thank you very much for your replay and help. Have a good day

 

[BentleyJ]

That sounds good. Since you are off grid my advice would be to oversize your PV array a bit so if you do have a few days of poor solar output the system will still provide enough power to keep you going. The inverter can take up to 8000W divided between the 2 inputs so 2 series strings of 8 panels per MPPT input would make a well balanced system that can power your house and charge the batteries at the same time.

 

[Mig54]

That sounds good. Since you are off grid my advice would be to oversize your PV array a bit so if you do have a few days of poor solar output the system will still provide enough power to keep you going. The inverter can take up to 8000W divided between the 2 inputs so 2 series strings of 8 panels per MPPT input would make a well balanced system that can power your house and charge the batteries at the same time.

Bentley,
I will consider adding more panels as you suggested. Thank you very much for your help. Have a great day!

 

[wheelman55]

Mig54. I am not an expert, however I consulted with experts before putting our off grid solar in place.

There are a lot of important things that you need to consider and be clear on before you “go solar”. Doing them incorrectly can have disastrous results: fire, electrical shock, death.

You need to understand:

1. Grounding and bonding. From the individual solar models, the array, the electronic equipment, the AC panel and circuits
2. How to configure your array, which is based on the max and min voltage that your equipment requires. Will it be one string of 10 or 12 modules, 2 strings of 5 or 6 modules, etc.
3. Read the fine print on your electronics as to how many batteries your gear will support
4. Where and what type of disconnect box
5. Same with combiner box, if you need one
6. Choosing the right type of wire and wire size from array to electronics to AC panel, to individual circuits
7. If you are on grid, how to connect to the local utility
8. If you are off grid, how to be your own utility
9. How to safely work around the high voltage of your system
10. How to properly torque ALL connections
11. How to commission the system along with a start up list if you ever need to shut it down
12. How to decommission the system along with a shut down list
13. You’ll need to write everything down so it’s simple for your spouse or a neighbor to understand for just in case
14. Where to place SPD’s (surge protection devices - think lightning protection) - both DC and AC SPD’s.

None of this is hard, there is just a lot of things to understand, hopefully before you spend a lot of money on things that might not be adequate or compatible.

Many have gone through this process, you can too. Just be safe

 

[sunshine_eggo]

8S would not be oversized.

It may be worth considering 72 cell panels in the 300-360W range. With those panels, you could do an (8-9)S2P array and over-panel your MPPT by about 25-35%.

 

[Mig54]

Mig54. I am not an expert, however I consulted with experts before putting our off grid solar in place.

There are a lot of important things that you need to consider and be clear on before you “go solar”. Doing them incorrectly can have disastrous results: fire, electrical shock, death.

You need to understand:

1. Grounding and bonding. From the individual solar models, the array, the electronic equipment, the AC panel and circuits
2. How to configure your array, which is based on the max and min voltage that your equipment requires. Will it be one string of 10 or 12 modules, 2 strings of 5 or 6 modules, etc.
3. Read the fine print on your electronics as to how many batteries your gear will support
4. Where and what type of disconnect box
5. Same with combiner box, if you need one
6. Choosing the right type of wire and wire size from array to electronics to AC panel, to individual circuits
7. If you are on grid, how to connect to the local utility
8. If you are off grid, how to be your own utility
9. How to safely work around the high voltage of your system
10. How to properly torque ALL connections
11. How to commission the system along with a start up list if you ever need to shut it down
12. How to decommission the system along with a shut down list
13. You’ll need to write everything down so it’s simple for your spouse or a neighbor to understand for just in case
14. Where to place SPD’s (surge protection devices - think lightning protection) - both DC and AC SPD’s.

None of this is hard, there is just a lot of things to understand, hopefully before you spend a lot of money on things that might not be adequate or compatible.

Many have gone through this process, you can too. Just be safe

 

[Mig54]

Wheelman,
Thank you very much for you advice and concerns, I will be very careful with all the work I do, and, when in doubt, I will get an electrician to help me. Writing the steps to startup and shutdown the system is a great idea. Everything will be in an electrical room and secure, except the panels and accesories required for them. I will hire an Pv installer to inspect system before it is use, just to make sure I didn not miss anything.
Take care and thank you very much for your help.

 

[Mig54]

8S would not be oversized.

It may be worth considering 72 cell panels in the 300-360W range. With those panels, you could do an (8-9)S2P array and over-panel your MPPT by about 25-35%.

8S would not be oversized.

It may be worth considering 72 cell panels in the 300-360W range. With those panels, you could do an (8-9)S2P array and over-panel your MPPT by about 25-35%.

I will check with my supplier if they have those panels. Thank you for your advise.