Audit Spreadsheet verification

Hi, I have filled the spreadshhet provided at the resources for sizing the system, are my results reasonable?





I am not sure the the solar array is correct, only 565 ? Also the Inverter seems too low.

I wanted to ask a question about the hours of full sun, can I use the number that the http://www.solarelectricityhandbook.com/ website gives for my location, the site is giving 4.09 in the lower winter but is per sqr. meter.

The fan is at 0 hours because this is the winter measurments, this are more challenging that the summer ones thats why I am focusing in them.


Thanks

Begginer7 said:

Hi, I have filled the spreadshhet provided at the resources for sizing the system, are my results reasonable?

View attachment 84670

Click to expand...

0.3 hours/day for fridge use is very low. A 10-20cu-ft fridge uses 1-2kWh/day - about 50X what you have budgeted. If this is a small "cooler" type of fridge, it likely uses less than that, but WAY more the 21Wh/day.

Begginer7 said:

I am not sure the the solar array is correct, only 565 ?

Click to expand...

This is actually a huge array for your incorrectly calculated (fridge) consumption. Sized based on:

2.3 days of battery autonomy coupled with the 1.0 days to recharge while under load with 4.1 solar hours. This means that your array needs to handle about 3-4X your daily needs. In other words, you're requiring that if you have NO sun for 2.3 days and drain your batteries, on the next sunny day, you will be able to completely charge your batteries AND power your loads for that day.

Your 100% max discharge is rarely recommended for any battery chemistry. For lead-acid, 50%. For LFP, 80%.

48V for such a tiny system is likely overkill unless you're looking to expand in the future.

Begginer7 said:

Also the Inverter seems too low.

Click to expand...

Nope. Looks right. Would simply get a straight 1000W inverter.

Begginer7 said:

I wanted to ask a question about the hours of full sun, can I use the number that the http://www.solarelectricityhandbook.com/ website gives for my location, the site is giving 4.09 in the lower winter but is per sqr. meter.

Click to expand...

Solar Insolation is always per sq meter. Standard insolation is 1000W/sq-m. Websites like that also assume some sort of optimal panel orientation and tilt AND average it over the year. Winter performance may be well below that.

If you want to see how your insolation varies throughout the year, simulate a system at:


You can specify your exact location, array size, orientation and tilt. It also factors weather into yield.

sunshine_eggo said:

0.3 hours/day for fridge use is very low. A 10-20cu-ft fridge uses 1-2kWh/day - about 50X what you have budgeted. If this is a small "cooler" type of fridge, it likely uses less than that, but WAY more the 21Wh/day.

Click to expand...

The fridge ( without a freezer) has a factory claim of 101 kwh per year, 101/365= 0.2767 kwh per day, so 27.67 wh per day, am I correct?

This is the energy sticker:



And the fridge:

sunshine_eggo said:

This is actually a huge array for your incorrectly calculated (fridge) consumption. Sized based on:

2.3 days of battery autonomy coupled with the 1.0 days to recharge while under load with 4.1 solar hours. This means that your array needs to handle about 3-4X your daily needs. In other words, you're requiring that if you have NO sun for 2.3 days and drain your batteries, on the next sunny day, you will be able to completely charge your batteries AND power your loads for that day.

Your 100% max discharge is rarely recommended for any battery chemistry. For lead-acid, 50%. For LFP, 80%.

48V for such a tiny system is likely overkill unless you're looking to expand in the future.



Nope. Looks right. Would simply get a straight 1000W inverter.



Solar Insolation is always per sq meter. Standard insolation is 1000W/sq-m. Websites like that also assume some sort of optimal panel orientation and tilt AND average it over the year. Winter performance may be well below that.

If you want to see how your insolation varies throughout the year, simulate a system at:

PVWatts

Estimates the energy production and cost of energy of grid-connected photovoltaic (PV) energy systems throughout the world. It allows homeowners, small building owners, installers and manufacturers to easily develop estimates of the performance of potential PV installations

pvwatts.nrel.gov

You can specify your exact location, array size, orientation and tilt. It also factors weather into yield.

Click to expand...

You are righ. made the changes you suggested:

Begginer7 said:

The fridge ( without a freezer) has a factory claim of 101 kwh per year, 101/365= 0.2767 kwh per day, so 27.67 wh per day, am I correct?

This is the energy sticker:

View attachment 84722

And the fridge:

Click to expand...

Says right there on the sticker. 0.272kW/24h

You multiply that by 1000 to get Wh, so that's 272Wh/day, which is very very good.

Begginer7 said:

You are righ. made the changes you suggested:

View attachment 84727

Click to expand...

Full load Wh is still listed at 631. It should be 882 with the corrected refrigerator consumption.

sunshine_eggo said:

Says right there on the sticker. 0.272kW/24h

You multiply that by 1000 to get Wh, so that's 272Wh/day, which is very very good.



Full load Wh is still listed at 631. It should be 882 with the corrected refrigerator consumption.

Click to expand...

Yes, again correcting it.





Is it correct?

Begginer7 said:

Yes, again correcting it.

View attachment 84741

View attachment 84742

Is it correct?

Click to expand...

Looks good. Round up to 600W of solar and make sure that covers you in winter

sunshine_eggo said:

Looks good. Round up to 600W of solar and make sure that covers you in winter

Click to expand...

Ok, but I would like to start if possible with one 1200 battery and one 410 panel. so can I make some changes to achieve this? I will reduce the hours of use and increase the discharge from 80 to 85 %. Also because the Wh of the battery are now around 1200 I will try a 12V battery:




Is this still ok?

I would need a 12V inverter of 1kW with a 40a MPPT controler this is the MPP PIP1012MSE at 450 Eur.
100 ah 12 V battery. Could be a SOK at 630 Eur.
1 410 W panel. Could be Jinka at 210 Eur.
Battery meter SOK 45 Eur
Wires around 400 Eur.

Total of 1735 Eur. Not bad...

Looks like that would work. IIRC, the PIP1012MSE is limited to 500W of solar.

sunshine_eggo said:

Looks like that would work. IIRC, the PIP1012MSE is limited to 500W of solar.

Click to expand...

Yes and not only that but it has a 0 load consumption "minor" to 25W, if I am I understanding this correctly it means that it will use about 30% of the energy of the panel just to run itself?

Do you know of any AIO or just inverter with similar characteristics that is not using as much?

Begginer7 said:

Yes and not only that but it has a 0 load consumption "minor" to 25W, if I am I understanding this correctly it means that it will use about 30% of the energy of the panel just to run itself?

Do you know of any AIO or just inverter with similar characteristics that is not using as much?

Click to expand...

Oh Wow... I usually don't forget that. Shame on me. These things are notorious for high idle consumption. You should count on 25W.

25W * 24h = 600Wh, i.e., it will be your highest consumption item. You need to re-run your spreadsheet with 1483Wh of consumption instead of 883Wh.

sunshine_eggo said:

Oh Wow... I usually don't forget that. Shame on me. These things are notorious for high idle consumption. You should count on 25W.

25W * 24h = 600Wh, i.e., it will be your highest consumption item. You need to re-run your spreadsheet with 1483Wh of consumption instead of 883Wh.

Click to expand...

This is huge, I have reduced the hours of computer to 3 in order to keep the battery at least with in the 2400 limit:





One way to get just one battery of 1200 is to find an inverter that takes only 10W and work with 1 day of storage capacity. Is this viable?, I have a generator on site.

It seems that the all in one option is not the best, I will have to look for separated inverter and charge controler. Any suggestions?

So with the zero load consumption of the MMP AiO we have a new budget:

2 Sok batteries 100ah 12 V 1260 Eur
MPP PIP3024MSXE 24V. 60A SCC 3KW 605 Eur
Sok battery meter 45 Eur
2 Jinkha panels 410W 460 Eur
Wires 400 eur

Total 2770 Eur

I have one question regarding the Spreadsheet, it seems that is not taking in to consideration any inefficiencies of the solar panels, is this something we need to add our selves?

Begginer7 said:

I have one question regarding the Spreadsheet, it seems that is not taking in to consideration any inefficiencies of the solar panels, is this something we need to add our selves?

Click to expand...

No. Panels are rated for 1000W/m^2, so the efficiency is already baked in to the input. When you use the solar hours, that's the equivalent number of 1000W/m^2 hours you get over the course of the whole day.

I want to ask a question that might seem silly but anyhow here it goes : a stand alone inverter like the Giandel 1200 W 24V, does it use all the time the battery to power the appliances or its also using the panels input directly to power the appliances?

Begginer7 said:

I want to ask a question that might seem silly but anyhow here it goes : a stand alone inverter like the Giandel 1200 W 24V, does it use all the time the battery to power the appliances or its also using the panels input directly to power the appliances?

Click to expand...

The Giandel has nothing to do with the panels. It ALWAYS draws from its DC source.

The MPPT is handling it.

In bulk mode, the MPPT should be pushing as much power as the array can provide and battery can take, regardless of loads. Loads will of course reduce the net current to the battery and could even exceed the available solar and cause a net drain.

In absorption/float mode, the MPPT is trying to maintain a constant voltage at the battery. If the load from the inverter forces the battery voltage to drop, the MPPT will add more current to try and keep the voltage steady.

In both cases, if the loads do not exceed the power of the array, the loads are effectively being powered by the array.

sunshine_eggo said:

The Giandel has nothing to do with the panels. It ALWAYS draws from its DC source.

The MPPT is handling it.

In bulk mode, the MPPT should be pushing as much power as the array can provide and battery can take, regardless of loads. Loads will of course reduce the net current to the battery and could even exceed the available solar and cause a net drain.

In absorption/float mode, the MPPT is trying to maintain a constant voltage at the battery. If the load from the inverter forces the battery voltage to drop, the MPPT will add more current to try and keep the voltage steady.

In both cases, if the loads do not exceed the power of the array, the loads are effectively being powered by the array.

Click to expand...

So as it follows during the night you cannot exceed the battery Whs but during the day its theoretically possible (with the corresponding sollar array) to actually consume many times the battery power size?

Begginer7 said:

So as it follows during the night you cannot exceed the battery Whs but during the day its theoretically possible (with the corresponding sollar array) to actually consume many times the battery power size?

Click to expand...

Yes. This is not an uncommon practice either - enough battery to get through the night under low utilization, but gobs of solar to power high drain items during the day. Batteries need to be big enough to handle solar inconsistency. You must also make provisions to ensure the batteries can't be exposed to more current than they can handle. Many units allow for limiting charge power while allowing all available solar for loads.

Obviously, with this setup, you may be severely limited when solar is not available.

I have reached the conclusion that the all in one solution is not for me, its too expensive. I have found an inverter that is ok for my needs its the Giandel Inverter 24V to 230V Pure Sine Wave 1200W Voltage Converter 24V PS-1200JCR/24V at about 200Eur, however its out of stock, could anyone please give me a recommendation on a similar product?