Off-Grid Inverters

[andrew.tkelly]

Hi,

While I've designed plenty of residential, grid-connected PV systems, I have a client that wants me to research options for a small off-grid array that would power a small guard booth. Due to a lack of rooftop space, I was considering a pole-mounted array consisting of 3 to 5 modules (the load is very small).

Question: Can I get some recommendations for a small, dependable off-grid inverter? Also, has anyone ever used a pre-fab pole-mount specifically designed to mount modules on? Open to recommendations as well.

Thanks in advance.

 

[pv_n00b]

You are going to need to research a battery and battery charger also. You can't just have modules and an inverter on an off-grid system. For small systems, Morningstar Solar makes nice charge controllers and a 300W inverter. If you just need lights and an outlet in the guard booth five modules might be overkill.

 

[PaulMmn]

Will there be a heater in the guard booth? A/C? Coffee maker? Refrigerator??

 

[andrew.tkelly]

PaulMmn It's mainly one overhead, flush-mounted luminaire, an outlet that is mainly for charging cell phones, and a small A/C unit. I should also mention they have a generator we'd like to incorporate into the overall system, but use it as little as possible.

Specs on the AC unit:
Cooling BTU/HR: 8000
Heating BTU/HR: 4000
Amps: 11.2
Max. Amps: 20.5
Volts: 115

 

[jaggedben]

For that AC unit power requirement and generator support you should probably be looking at the Outback FXR/VFXR series (best reputation, higher price) or the Conext SW series (somewhat lower on both).

Given your comment about roof space, you probably also need to figure on advising your client on building more space to house such equipment, plus batteries.

 

[pv_n00b]

Once you add AC it's no longer a small system. It's completely different from grid-tied design, PV array and battery sizing really have nothing in common between the two. Good luck.

 

[GoldDigger]

If no other benefit, the battery and inverter, even without PV, will allow you to run the genererator intermittently instead of continuously. If it is a diesel engine it will be happier running near full load when it is running.

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