3.68Kw system on three phase

[Davidp]

Hi

I am an end user and want a 3.68kW system installed at work.

We have three phase but don't have the money to do the full 10kw job.

My installer is proposing installing a 3.68kw system and connect to only one phase.

He is using an SMA 4000TL and 16x Upsolar 230 panels

My concern is putting that amount of energy into one phase and the effect that it might have on our 3 phase equipment.

I take it that because it is 3.68kw that the installation notification to the electricity company is simpler than the larger systems.

I have downloaded the SMA design software and had a play with that but it recommends 17 or 18 panels to get the correct efficiency from the inverter.

If we did this I take it would make things more difficult from a permission point of view.

Many thanks

 

[SolarCity]

I think that the 4000TL is a little oversized. I would have thought an SB3300 would be a better choice in this instance. A Fronius IG TL 36 would be even better.

Installing on a single phase of a three phase system is not a problem - it will have effect on your current three phase equipment.

Being a 3.68kWp system, the DNO do not need prior notification. However, prior notification will only delay the job a matter of weeks so sizing the system to suit them rather than the FITs tariff ceiling is not a wise economic move.

 

[Davidp]

Many thanks

I think the plan was that the inverter was chosen because of the two inputs and the plan was originally to have the full 4kw with 17 or 18 panels.

My limited research showed that it is the output of the inverter is more important than the possible input, so could we increase the panels and still get under the 3.68 limit (or is it 4kw?)

 

[SolarCity]

Is there any design reason why the two MPPT inputs are required?

Actually, the output and the input of the inverter are important. Smaller inverters are more efficient at lower wattages: - An inverter rated at 1200w will perform much better at 1000w than an inverter rated at 3000w.

With a Fronius IG TL 36 (which has only one MPPT) is limited to 16A anyway which means that the DNO need not be informed.