30v Panels, what's the highest save voltage for an array.

chal

I've got 12 large 30v 270w panels I had planned on setting up in series parallel (off grid), but am now considering whether having a 60v or 90v array on my roof would be dangerous/a fire hazard since I don't see arrays above 48v.

Any advice would be appreciated.

niel

Re: 30v Panels, what's the highest save voltage for an array.

chal,
i think you are confusing battery voltage with pv voltage. many have arrays of pvs with voltages in the ranges you cite. just be sure that the voc of your particular pvs compensated for the temp on the coldest temp recorded for your area will not exceed the max voltage parameters for the controller you select to use. do note that this would be an mppt controller.

the fire hazard will not likely be any worse at 90v than 45v or so. the hazard comes into play when not installing correctly or using wrong or inferior components.

bill von novak

Re: 30v Panels, what's the highest save voltage for an array.

chal wrote: »

I've got 12 large 30v 270w panels I had planned on setting up in series parallel (off grid), but am now considering whether having a 60v or 90v array on my roof would be dangerous/a fire hazard since I don't see arrays above 48v.

Any advice would be appreciated.

Modern string-inverter systems are generally rated to 600 volts, and thus arrays commonly are designed to operate at 300-450 volts. (Leaving some margin at the top end so cold/sunny/low load conditions do not push voltages over 600V.)

Modern off grid charge controllers can be had that go to 250 volts. One goes to 600 volts. Depends on which charge controller you use. In your case, if 30V is V_pmax then Voc is around 36V. I'd consider 4 in series for a system voltage of 144V with a 200V charge controller, or 3 in series with a 150V charge controller.

zoneblue

Re: 30v Panels, what's the highest save voltage for an array.

Theres one downside to going over 140V is that you cant use the midnite/cbi breakers in the combiner, your into touch safe fuse territory. Also if you are planning on doing this yourself, most jurisdictions get more twitchy about DIY wiring over 120V. Man youve got some reading ahead. Or get help?