Welding Load in off grid (PV + storage)

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mark-moussa asked Dec 8, '19

Welding Load in off grid (PV + storage)

Hi,

I am a solar energy design engineer.

I have been always asked if it's okay to supply a welding machine in a solar micro-grid consisting of PV+Storage only (no back up generator).

As far as I know, the major complication in such a setting is that welding machines are very complex to monitor their actual consumption due to power factor and thus in a micro-grid it's difficult to have an accurate metering of the welding load and charge the user properly.

I need your advice if the above information is precise and if the idea of applying a welding load in an off-grid solution (PV+storage only) is applicable and have no other complications (for example, high starting currents may cause very high discharge currents from batteries during cloudy days or whenever there is pv deficit).

Thank you in advance

offgrid

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klim8skeptic ♦ commented · Dec 08, 2019 at 09:18 AM

hi mark,

welding using batteries only?

or using a battery inverter and ac welder?

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mark-moussa klim8skeptic ♦ commented · Dec 10, 2019 at 03:13 PM

Hybrid inverter with ac welder

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Answer 1 · 2019-12-08T11:00:37Z

Daniël Boekel (Victron Energy Staff) answered · Dec 08, 2019 at 11:00 AM

Hi @Mark Moussa

Welding doesn't have to be a problem, make sure the inverter is plenty big enough, I personally have a 10k unit in my boat, and welding goes great with the stable power it provides.

for light welding a 3k unit might be enough, but I'd recommend 5k or higher.

Just follow normal precautions, like no welding on something that is connected to the (micro) grid to prevent currents flowing through paths other than the welding wires. And no delicate electronics nearby.

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mark-moussa commented · Dec 08, 2019 at 11:14 AM

Thanks for your answer.

So are lead acid batteries okay to experience these high discharge currents coming from welding machines ?
what about the actual consumption reading issue ?

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Daniël Boekel (Victron Energy Staff) ♦♦ mark-moussa commented · Dec 08, 2019 at 06:21 PM

Hi @Mark Moussa

If your batteries are sized properly for your inverter capacity, this should not be a problem, but I don't know if they are.

What do you mean by 'consumption reading issue'?

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