Have I been Conned

neschofield

In Feb 2012, I had a (supposedly) 4kw solar pv system installed and I noticed in the good summer days that it wasn't generating more than 3kw. So I looked closer at the Sunny Boy inverter specification using Sunny Explorer and it says at 100% the nominal power is 3kw (see attached images). Also the model is shown as SB 3000TL 20 and when I look it up on the web ,sure enough, it is a 3kw model.

Have I been conned ?

SteveCritten

What's the make and model of the panels and how many? Are you south facing? If your orientation isn't perfect then if it is a 4kw system it won't produce it's full potential, but obviously if the inverter is only rated to 3kw it seems a bit strange.

Jazz Monkey Jr

I have just had my 4kw system installed and he used a sunny boy 3600TL inverter which has a maximum rated Input DC power of 3880W and max rated output power at 3680W at 230V so you need to look at yours! If you're south facing you need something higher than 3000W but if it is shaded or not south then it is probably OK

Yours is a sunny boy with rated input of 3200W DC and output of 3000W AC so looks like they're cutting costs if your panels are producing more than 3200W

neschofield

Steve,

There are 16 Hyundai Panels with a North Easterly aspect. Granted thats a poor aspect but it maxed out at 3kw for several weeks over the summer.

Jazz Monkey Jr

I'd get back on to them.

neschofield

...and mysteriously since I called them, the stats for the days in question have disappeared. So when I go into Sunny Explorer for those days, nothing at all is shown...almost as though they have been removed. Anyone can connect to these by bluetooth, so I am naturally suspicious.

Jazz Monkey Jr

Not anyone can connect by Bluetooth - only the sunny beam.
This is what I have been told.
I have the portal so I can see online and which model I have.

devbias

Sounds to me that the inverter is on the low side.
I've just had a system proposed with 16 x 250W hyundai panels.
The design engineer suggested a SMA 3600TL which I questioned given a 4KWH system would be connected to it.
The response I was given that the 3600 could handle a peak load of 3.8KWH.
I've decided to pay the extra for the 4000TL but not going to be installed for a little while yet but would be interested to know how you get on with this one.

Was the Company you used recommended to you or cold call and if you don't want to name them where are they based?

SteveCritten

Recently been offered a similar system for £5k with same panels and inventor how much are you paying?

GaryMo

The 3600TL could well yield more annually than a 4000TL.
For all the times when you're not peaking close to 4kWh then the 3600TL will probably be more efficient.
Get your company of choice to run figures for both inverters with your chosen panels through their software of choice, PVSOL being a popular one and see what it says.

I have a 4kWp system with a Fronius IGTL3600 inverter. I personally chose this over 4000TL inverters because it yielded more in my case.

This text is taken for THIS ARTICLE
"It is common in the industry to oversize the PV array by using a PVto- inverter sizing ratio of around 1.15. After all, a well-designed system will typically have end-to-end system losses of about 15%–16%. Oversizing the array ensures that the inverter is driven to its maximum output, at least during the best sun hours of the day. System designers who are looking at a 20-year design life for the system will usually size the array-to-inverter using a 1.2 to 1.25 ratio. Some PV system integrators even routinely use a 1.3 ratio."