Audit Spreadsheet verification
- Thread starter Begginer7
- Start date
But what about the AIO inverters feature that allows for charging and using the appliances, does this mean that using an AIO with this function will extend the life of the battery as it sould not be used during the day?
sunshine_eggo
Happy Breffast!
A properly configured AiO or a standalone MPPT will use available solar for loads when the batteries are full. This is typically accomplished by the specification of a float voltage. A load will cause the battery voltage to drop, so the MPPT will add current to keep the battery voltage from dropping, thus powering the load.
I spoke to two persons, one battery vendor and one pv installer, both mentioned something I dont fully understand, the fridge that I am intending to use is a static one that has a compressor that starts and stops, from the kill a watt measurments that I made the surge power is about 12 times the continous one, so for a 70W fridge should be about 840W, in regards to the inverter that is ok I will probably get a 3000W, but they mentioned that this consumption although it lasts only a few seconds it consumes 840w/12v=70Ah, that is 70% of a 100Ah battery is this correct?
sunshine_eggo
Happy Breffast!
No. 840W/12V = 70A, not Ah.
70A for three seconds is:
70A * 3sec/(3600sec/hr) = 0.0583Ah
I read the manual of the inverter MPP PIP3024MSXE 24V. 60A SCC 3KW, however they do not mention any maximum of batteries that I could install I know that the battery itself it has some restrictions eg SOK 12V not more than 4 in series, but do inverters have other restrictions?
sunshine_eggo
Happy Breffast!
It's up to you.
1.0 means you basically have an array that can provide all power you need in a day AND completely recharge your battery in that same day. This can really blow things out of proportion if you have a large battery with multiple days of backup.
If you have 3 days of battery power, you need an array that can provide 4X your daily need.
1.5-2.0 is probably more sensible. A backup generator takes some of the pressure off.
sunshine_eggo
Happy Breffast!
Sure. It just necessitates the use of a generator if you ever have more than 1 bad day in 6.
Which in winter I will probably have but I have a generator
sunshine_eggo
Happy Breffast!
Should be fine. In reality, many design a system with an infinite number of days having only a day's worth of solar for a day's worth of batteries.
I have a doubt about the surge wattage, lets say I have 3 static refrigerators and they all happen every now and then to start at the same time, however my inverter is of 1200W and surge of 2400w, the 3 refrigerators surge at the same time need more than 2400w but continous they are within the range, so every now and then 1 of the refrigators will not have the surge to start, ok no problem it should try again in a few seconds and then it will be ok, is this correct?
I have found an inverter that has lower no load consumption so that it will allow me to stay within the 2400 Wh range so I can go by with 2 acid batteries with one day of storage, the Audit Spreadsheet looks now like this:
Based on this my system would be:
2 410W panels 50 VOC. 10.1V Isc at 488 eur
SCC Victron Blue Solar 100 - 30 at 228 eur
Inverter Victron Phoenix 24 - 800 at 343 eur
2 Gel Batteries 12V 100ah at 535.5 eur
Total about 1700eur
Does it all make sense?
Pending:
Battery charger from generator
Wires
Based on this my system would be:
2 410W panels 50 VOC. 10.1V Isc at 488 eur
SCC Victron Blue Solar 100 - 30 at 228 eur
Inverter Victron Phoenix 24 - 800 at 343 eur
2 Gel Batteries 12V 100ah at 535.5 eur
Total about 1700eur
Does it all make sense?
Pending:
Battery charger from generator
Wires
sunshine_eggo
Happy Breffast!
Numbers appear to check out.
There's a Multiplus 800 that's essentially the Phoenix + a built-in charger, and it's idle power consumption is 8W:
I believe it comes in the "Compact" version.
Additionally, 24W for a 800VA Phoenix sounds crazy high. Where are you getting your numbers?
There's a Multiplus 800 that's essentially the Phoenix + a built-in charger, and it's idle power consumption is 8W:
I believe it comes in the "Compact" version.
Additionally, 24W for a 800VA Phoenix sounds crazy high. Where are you getting your numbers?
That 24W is a mistake it should be 7W. The Multiplus C 24/800/16-16 which I think you are reffering to it comes with a charger but it has a price of 900eur, at the moment out of my budget, however I had only a superficial look for chargers, so far the ideas I got is that for acid batteries it should not be that difficult to find one, I got a quote for an AGM one for 100 eur, something that is a bit concerning is that I read that recharging an acid battery can take many hours, the generator I have on site is huge is a GBW15, I dont want to put it on for 5 hours to charge one battery.
sunshine_eggo
Happy Breffast!
Yes, lead acid batteries can typically only be charged out about a .1 to .2C rate. From 50%, that means at least a 3-hour charge time.
But if I have 2 in series for a 24V system it would still take 3 hours? What about LiFePo4 batteries?
sunshine_eggo
Happy Breffast!
Of course. C rate is dependent on the battery capacity. 100Ah is 100Ah at any voltage, thus requiring 10-20A. If you have to put 50Ah in, you'll need at least 3 hours @ 20A.
If you put the 12V in parallel, now you have 200Ah. Now you charge at 20-40A. If you have to charge 100Ah @ 40A, you'll need at least 3 hours.
Lead-acid requires a fairly long absorption time to get truly full. The 3+ hours I mention will get you nearly fully charged and would be fine for occasional help, but the batteries should regularly be topped to to truly full, and that may require 2-4 hours in absorption phase alone.
LFP can typically charge 0.5C or higher with a very short absorption period - usually less than 30 minutes.
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