How Can I Design an Off-Grid Solar System with Panels on Multiple Roofs?

[Envergure]

I'm designing an off-grid system with solar panels on six different roofs spread out over about a hectare. There is also a generator on the site for backup and when the solar isn't enough. I need all the solar panels to feed one main distribution panel. What are my options?

I've considered connecting all the panels together and feeding one charge controller, but I'm concerned about shading due to the different roof locations. I've considered connecting several charge controllers to a central battery bank, but this requires a lot of very heavy, 48 VDC lines to be laid all over the site.

I've considered using multiple inverters in several ways. (1) Microinverters. Unfortunately, I gather they don't work well off-grid. (2) One inverter per building. Trouble is, I don't know how to parallel them. (3) One "dumb" inverter and five grid-tie inverters that will (hopefully) sync to it properly. I have a hunch this won't work since I think grid-tie inverters are designed based on the assumption that the grid is much more powerful than the inverter.

Thanks for your advice. This is my first design as an electrical EIT and I'm a little out of my depth.

 

[berkeman]

I'm designing an off-grid system with solar panels on six different roofs spread out over about a hectare. There is also a generator on the site for backup and when the solar isn't enough. I need all the solar panels to feed one main distribution panel. What are my options?

I've considered connecting all the panels together and feeding one charge controller, but I'm concerned about shading due to the different roof locations. I've considered connecting several charge controllers to a central battery bank, but this requires a lot of very heavy, 48 VDC lines to be laid all over the site.

I've considered using multiple inverters in several ways. (1) Microinverters. Unfortunately, I gather they don't work well off-grid. (2) One inverter per building. Trouble is, I don't know how to parallel them. (3) One "dumb" inverter and five grid-tie inverters that will (hopefully) sync to it properly. I have a hunch this won't work since I think grid-tie inverters are designed based on the assumption that the grid is much more powerful than the inverter.

Thanks for your advice. This is my first design as an electrical EIT and I'm a little out of my depth.

Sounds like an application where HVDC would be the best way to tie them together...

 

[anorlunda]

I've considered using multiple inverters in several ways. (1) Microinverters. Unfortunately, I gather they don't work well off-grid. (2) One inverter per building. Trouble is, I don't know how to parallel them. (3) One "dumb" inverter and five grid-tie inverters that will (hopefully) sync to it properly. I have a hunch this won't work since I think grid-tie inverters are designed based on the assumption that the grid is much more powerful than the inverter.

I would start with the manuals for whatever inverters you are considering. I expect that they will address the issues you mention, and they will provide recommendations and wiring diagrams.

You may have enough panels to consitute some real safety problems if they are not connected properly. That is another good reason to follow the controller/inverter manufacturer's advice.

Good luck. Maybe you can post back here again with your conclusions.