I am new to solar energy.

I have recently installed the following:

1 x Mecer (Axpert) Hybrid MKS 3Kva 48V inverter

4 x 330W (72 cell) PV panels

4 x105Ah 12v deep cycle batteries.

 

My current settings using Watch Power is:

Back to grid voltage = 46V

Back to discharge Voltage = 54V

Battery cut off voltage = 42V

Charger source = Solar

Output source = Utility

Battery type = AGM (not sure what this is)

My question is - Are these settings correct?

How do I set that the batteries get charged using solar?

My average Kwh usage prior to installing the PV panels and inverter was 50Kwh per day and it has not changed much.

Any advice on getting my daily Kwh usage down will be a great help.

 

Regards

 

39 minutes ago, azharc said:

Charger source [priority] = Solar

 

This says that you want to charge from solar energy only, never the grid (or whatever is connected to AC-in; you didn't say if you are off-grid or not).

You might want to consider SnU (Solar and Utility) if that's available on your model, at least at times when it's raining.

 

Quote

Output source [priority] = Utility

That says as soon as there is AC at the AC-in terminals, that will be used to supply the loads. Usually you would use SbU (Solar, battery, utility in that order) to save grid usage, or SOL (Solar first) to keep the battery ready for blackouts and run the loads from utility (if present, obviously)  all night. The election isn't that far away now 😮

Quote

Battery type = AGM (not sure what this is)

AGM = Absorbed Glass Matrix, a high end sealed lead acid battery type. That's probably OK for your deep cycle batteries, although if you tell us the brand, others can tell you if they need special requirements (like a higher charge voltage or the like).

49 minutes ago, azharc said:

Back to grid voltage = 46V

Back to discharge Voltage = 54V

I'd certainly increase the back to grid voltage; the default voltage is far too low. You want to keep your battery from discharging that low. You'll have to experiment a bit, I'd start with about 50 V. You might want to increase the back to discharge voltage a bit too.

Quote

My question is - Are these settings correct?

It depends on what you want to achieve. My suggestions are based on guesses for what you want.

Quote

How do I set that the batteries get charged using solar?

The batteries will always get charged from solar when available. It's more important to decide what powers the loads and when.

Quote

My average kWh usage prior to installing the PV panels and inverter was 50 kWh per day and it has not changed much.

That's really quite high, and your system is really quite small. I suspect you could reduce your usage quite a lot more: LED lights, induction cooking, high efficiency fridge and freezer, etc. I was using a low efficiency freezer for a long time; it finally died aged 20 years (motor ran 24/7) a week ago. Now my depth of discharge has gone from 75% to 60% (LFP battery; don't expect to discharge your lead acid battery more than 50%).

Thanks so much for your advice.

5 hours ago, Coulomb said:

Output source [priority] = Utility

I have just changed the Output source to SBU and will monitor the Kwh usage over the next few days.

5 hours ago, Coulomb said:

Back to grid voltage = 46V

Back to discharge Voltage = 54V

I will change the back to grid voltage to 50V and back to discharge to 58V.

5 hours ago, Coulomb said:

Battery type = AGM (not sure what this is)

The brand of the battery is Dixon a local brand. (Deep cycle)

5 hours ago, Coulomb said:

My question is - Are these settings correct?

I would like to reduce my daily Kwh usage by at least 50% (if I can afford to do it!!!).

Would I require additional PV panels and more batteries to get to this target.

 

5 hours ago, Coulomb said:

My average kWh usage prior to installing the PV panels and inverter was 50 kWh per day and it has not changed much.

I am looking at installing Kwikot Kwiksol Vacum tubes to feed off my existing electrical geyser in the near future, this should reduce the Kwh I think!!!!

Once again thanks so much for your advice.

Edited May 1, 20197 yr by azharc

9 hours ago, azharc said:

I would like to reduce my daily Kwh usage by at least 50% (if I can afford to do it!!!).

Would I require additional PV panels and more batteries to get to this target.

Let's make some basic assumptions. Your daily usage is presently 50kWh/d, so the target is 25kWh/d It will be less with the solar geyser, but let's see how close, or not, we get with the small system.

Assume equipment is new (solar output fades to 80% over 25 years, batteries fade), ignore losses, assume ideal solar conditions of 80% of nominal output for 5 hours per day, or 4 kWh/kW/d.

With 4 x330 W panels, that's 1.32 kW, so 1.32 x 4 = 5.28 kWh/d. That's a fifth of your goal. 

4 x 105 Ah batteries @ 50V = 105 Ah x 50 V = 5.25 kWh, but it's lead acid, so assume 50% DOD (that's heavy for lead acid) = 2.63 kWh. Suppose that 40% of your usage is at night, so the target would be 25 x 40% = 10 kWh. So you are at least 50% short on battery energy.

Your inverter is 3 kVA, so you can't run all your loads off it. But if you remove the big items like stove, oven, geyser, and all but the smallest air conditioners, perhaps pool pump, it may handle the rest most of the time. You and the whole family have to change habits and be careful to not use more than one large load at once, or the small inverter will be on utility constantly.

Then there are cloudy and rainy days, and the shorter days of winter with the higher heating loads (amount depending on location).

Not what you wanted to hear, no doubt, but these are the realities.

[ Edit : inverter is 3 kVA, not 3 kWh. Duh.] 

Edited May 1, 20197 yr by Coulomb