Stand Alone System - Missing Energy

[bendesa1962]

I'm working on a stand alone system and have a question about the simulation result.

Actually the system is producing way to much energy compared to the consumption.

Excess Unused Energy is 1437 kWh per year

But still there is a Missing Energy Quantity of 97kWh per year.

I don't understand that to be honest?

Hope someone can help me out

Many thx

Ben

[Lazare Fesnien]

Hi, 

These results are annual, to understand where the missing energy comes from you can look at the diagram of the losses month by month in order to control these values.

Regards,

[bendesa1962]

Hello,

many thanks for your reply. Yes I have noticed that the missing energy can be seen in the diagram per month. 

I'm playing a bit with the simulation of PVSyst with different Off Grid Designs. I must say that I don't understand

the behavior of the simulation completely. But probably that's because of my lack of knowledge (-: 

I also don't understand all terms mentioned in the simulation report. I hope you can help me out. I already want to thank you for that. 

First the load profile for the stand alone system:

The first system I designed has the following components:

 

3,300 Wp  PV Modules Longi 6 x 550 Watt Mono

Lithium batteries 3 x 48volt 100Ah

Outback Flex Max 60

The main results for this system are:

Actually there is a lot of excess (unused) energy.

The performance ratio is bad 55%

Missing energy is only 1.6% of the time, that’s good

 

How can we make this system better?

By better I mean:

Better Performance Ratio

Less unused energy.

Since there is a lot of unused energy I would expect that we can make the system smaller:

The second system I designed has the following components:

2,200 Wp  PV Modules Longi 4 x 550 Watt Mono

Lithium batteries 3 x 48volt 100Ah

Morningstar Tristar 45 36 / 48

The main results for this system are:

I have the following questions about these main result:

How can the specific production be 720 kWh/kWp/year compared with 1661 kWh/kWp/year of the first design. I would expect it to be close to each other.

The available energy is absolutely not enough to support the daily consumption of the household. 10.5 kWh.

365 x 10,5 kWh = 3833 kWh

Available energy = 1583 kWh

How can the simulation mention unused energy 1346 kWh, that is not possible in my view. There is a lack of energy of 3833 - 1583

How can the simulation mentioned missing energy 0 kWh / year

How is this possible?

Actually this looks like the most optimal system.

Performance ratio is good, no missing energy. So this looks like the best solution. But I really have my doubts about it. But I hope you can explain it to me.

Can you give some explanation about the terms

SOW ?

And why does the simulation of design 2 gives a battery life of 5 years while design 1 doesn’t?

Many many thanks

Kind regards

Ben