Solar system to power AC motors

[solar101]

One of my project has 15 motors running at a Ready mix Concrete plant, each with different HPs ranging from 0.75 till 50HP. All the motors are AC powered and they have a 50kVAR capacitor bank installed. They want to go Solar.

My solution would be to use a VFD to that by varying its frequency at the start-up the inrush can be subsidized. But then since the motors run by batch by batch process its not possible for them to be connected to a single VFD. Individual VFD for each motor would be really expensive.

Does anyone else have any other solution ? Please do share.

/Rex

[russ]

Hi Rex - Welcome to Solar Panel Talk!

If you think the individual VFDs are expensive wait until you get a price for the solar equipment including batteries - it will be in the range of astronomical.

A rule of thumb is that off grid solar costs 10 times or more what power from the grid costs - in the US.

Are you presently running these motors off a DG set or the grid?

[solar101]

Hi Rex - Welcome to Solar Panel Talk!

If you think the individual VFDs are expensive wait until you get a price for the solar equipment including batteries - it will be in the range of astronomical.

A rule of thumb is that off grid solar costs 10 times or more what power from the grid costs - in the US.

Are you presently running these motors off a DG set or the grid?

These motors are presently powered through grid and A DG set is present at the site as a back up. Yea but using batteries for inrush current is not advisable as it would drain the whole battery within milli seconds. I was looking at the Inverters with variable frequency but that too when multiple motors run, cant handle inrush current.

[russ]

Forget inrush - just the total draw will require a large system plus you have to have batteries to even operate the system - unless you could go grid tie in which case the grid acts as your battery.

Whatever boss came up with the nightmare should forget about it in a few days.

You are using the most economic power sources right now.

Come your monsoon seasons solar would present other problems anyway. Is one of your problems that the grid is often down?

[solar101]

Forget inrush - just the total draw will require a large system plus you have to have batteries to even operate the system - unless you could go grid tie in which case the grid acts as your battery.

Whatever boss came up with the nightmare should forget about it in a few days.

You are using the most economic power sources right now.

Come your monsoon seasons solar would present other problems anyway. Is one of your problems that the grid is often down?

Yea, We in India have problem with grid. ON a regular day there is a 3 to 4 hrs of black out and with ever soaring diesel prices..not heads are turning towards Solar off grid systems.

[russ]

Yea, We in India have problem with grid. ON a regular day there is a 3 to 4 hrs of black out and with ever soaring diesel prices..not heads are turning towards Solar off grid systems.

Grid tie is out as during the failures you would have nothing.

A hybrid system is possible so you have power from the system/batteries when the grid is down.

Some of the guys may be able to give you an idea of the cost in the US - it will put your boss in sticker shock though.

You have government funds available to help with the cost?

[solar101]

Grid tie is out as during the failures you would have nothing.

A hybrid system is possible so you have power from the system/batteries when the grid is down.

Some of the guys may be able to give you an idea of the cost in the US - it will put your boss in sticker shock though.

You have government funds available to help with the cost?

Yea i am goona make a detailed report on options available for such a type of system. I feel that to power a 37.5kW AC motor is out of option using solar but i will just try to find a solution to power atleast the 11HP motors with the a VFD-battery backup option.

Yea we have a 30% capital subsidy on Off grid system and 70% subsidy on hybrid systems

[russ]

Yea i am goona make a detailed report on options available for such a type of system. I feel that to power a 37.5kW AC motor is out of option using solar but i will just try to find a solution to power atleast the 11HP motors with the a VFD-battery backup option.

Yea we have a 30% capital subsidy on Off grid system and 70% subsidy on hybrid systems

The hybrid system - 70% is what you are talking about. The subsidy may make it doable for you.

Read up about batteries - they are a key component and consumables. My experience there is that it will be difficult to get someone to babysit the batteries so they are not destroyed in short order.