diy solar

diy solar

max panels to attach

mudk

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Joined
Dec 30, 2019
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37
Hi,
i have a 5kw inverter. I would assume that I would get solar panels that W add up to 5000W.
However the hand book is saying:
INVERTER MODELVM5000
Max. PV Array Open Circuit Voltage145Vdc
PV Array MPPT Voltage Range 60~115Vdc

it is then cosidering 250W panels:
Maximum Power (Pmax)250WReccomend:
Max. Power Voltage Vmpp(V)30.1V1. 2 pieces in serial and 6sets in parallel OR
Max. Power Current Impp(A)8.3A2. 3 pieces in serial and 4 sets in parallel
Open Circuit Voltage Voc(V)37.7V
Short Circuit Current Isc(A)8.4A

Now what i dont understand is in both of their recommended set ups has a total of 12 panels, so 250w times 12 is only 3000W.

How will that help me cover my needs if I want to use 5kw off grid?
 
The 5000w inverter output rating is not the same as the PV charger watt rating that is inside the inverter/charger box. Look for a max PV input number.
 
Post more specs on the charge controller. Better yet, post a link to it.

Do note that the max PV input voltage of your SCC is 145V. That's based on the temperature adjusted Voc of your panel array. You have a panel with a Voc of 37.7V. Your should work out a panel arrangement that is 3SxP where x will be determined with more info. Having 3 in series of the most you can do since 4 will exceed the max PV input voltage.
 
The 5000w inverter output rating is not the same as the PV charger watt rating that is inside the inverter/charger box. Look for a max PV input number.

So does that mean with this panel set up, I should be able to run 4-5 KW sytem?
 
Post more specs on the charge controller. Better yet, post a link to it.

Do note that the max PV input voltage of your SCC is 145V. That's based on the temperature adjusted Voc of your panel array. You have a panel with a Voc of 37.7V. Your should work out a panel arrangement that is 3SxP where x will be determined with more info. Having 3 in series of the most you can do since 4 will exceed the max PV input voltage.
 
So do you have the VP 3000 24 volt or the VM 5000 48 volt? VP 3000 =1560 watts as far as panel max. VM 5000=3000 watts as far as panel max.
Inverter output for the VP 3000 is 3000 watts in 230 volts and the inverter output for the VM 5000 is 5000 watts in 230 volts.
 
So does that mean with this panel set up, I should be able to run 4-5 KW sytem?
No. I understand there are things you need to learn. Here are the major bullets.
1. Inverter watts rating is max load it can carry/supply. A 1500watt toaster oven would need more than a 1500W inverter to work.
2. If you plan to max out the inverter, that will require a specific max amps from the battery...battery must have enough current available.
3. Your battery must have enough energy storage (how large) to carry your load for the time required. I put in a system at our deer camp with the goal to power our building lights for 20 hours without recharged. And it needs enough peak current to carry (say a coffee grinder) for a few minutes.
4. You need a battery charger that will charge the battery in the time that you are okay with but not so fast to cook the batteries.
5. You need a power source to power the battery charger, like some solar panels.

The solar panels have nothing to do with bullet 1 and 2. They only affect bullet 3 in that the batteries are charged more or less as fast as you drain them, depending on your load and depending on the solar available. Solar available means both the sun and how many panels. For a given sun condition, if you double your panels, you can shorten your charge time. If you must fully charge a fully drained battery every day, you need a LOT more panels than if you only use 10% of your battery per day and can survive 3 or more days without good sun. In summery...A larger inverter will support a larger load and that will drain the battery faster. A larger charger and more panels will charge the battery quicker under given sun conditions.

Hope that helps.
 
So do you have the VP 3000 24 volt or the VM 5000 48 volt? VP 3000 =1560 watts as far as panel max. VM 5000=3000 watts as far as panel max.
Inverter output for the VP 3000 is 3000 watts in 230 volts and the inverter output for the VM 5000 is 5000 watts in 230 volts.

VM5000
 
4 x 185 AH (@ 20hrs) tubular batteries.
So that’s like 5000W for 40 minutes on paper.
But you won’t be able to do that rate of discharge for 40-ish minutes. The battery bank is ~4400Wh
What are you running that requires 4-5kW? And is it constantly? For how long? What is the minimum steady kW?
 
So that’s like 5000W for 40 minutes on paper.
But you won’t be able to do that rate of discharge for 40-ish minutes. The battery bank is ~4400Wh
What are you running that requires 4-5kW? And is it constantly? For how long? What is the minimum steady kW?
to be honest, 5kw is the theoretical. At most our whole house uses 2kw MAX. And then 1.2 kw ontop if we run the deep well motor. (for 10 mins)

I was just curious if the panel set up max allowed is 3kw, and I don't want to drain the batteries, the max I can use is 3kw. If I go over, the inverter will start using the batteries. Is that the case?
 
No. I understand there are things you need to learn. Here are the major bullets.
1. Inverter watts rating is max load it can carry/supply. A 1500watt toaster oven would need more than a 1500W inverter to work.
2. If you plan to max out the inverter, that will require a specific max amps from the battery...battery must have enough current available.
3. Your battery must have enough energy storage (how large) to carry your load for the time required. I put in a system at our deer camp with the goal to power our building lights for 20 hours without recharged. And it needs enough peak current to carry (say a coffee grinder) for a few minutes.
4. You need a battery charger that will charge the battery in the time that you are okay with but not so fast to cook the batteries.
5. You need a power source to power the battery charger, like some solar panels.

The solar panels have nothing to do with bullet 1 and 2. They only affect bullet 3 in that the batteries are charged more or less as fast as you drain them, depending on your load and depending on the solar available. Solar available means both the sun and how many panels. For a given sun condition, if you double your panels, you can shorten your charge time. If you must fully charge a fully drained battery every day, you need a LOT more panels than if you only use 10% of your battery per day and can survive 3 or more days without good sun. In summery...A larger inverter will support a larger load and that will drain the battery faster. A larger charger and more panels will charge the battery quicker under given sun conditions.

Hope that helps.
Ok, so if I understand you correctly, the inverter does not directly convert solar energy to AC to power the load? The inverter charges the battery with the incoming from solar and then provides power to the load by battery DC to grid AC?
 
Ok, so if I understand you correctly, the inverter does not directly convert solar energy to AC to power the load? The inverter charges the battery with the incoming from solar and then provides power to the load by battery DC to grid AC?
If you get technical, there are "all in one" type inverters of two different types in regards to how they charge the battery and how they power the inverter. I don't want to try to explain those two types, as it doesn't matter for what you are trying to understand. I will describe the most common and older design's function. These are the type that must have a battery. Think of your inverter as an inverter, solar battery charger, and a grid powered battery charger, all in one box. The inverter takes DC and turns it to AC. The solar battery charger takes solar power (DC) and regulates it to charge the battery. The battery is always available, so this is the most available power source for the inverter. Most "all in one" units, you can program to charge off the battery of the solar, charge off of the grid, or a combination of both with some rules as to when to use which of the two sources. If you are "off grid" the grid powered battery charger will not be an option.

When you shop for an "all in one" your peak power demand is a factor to pick what size. The size of the built in charger might also be a shopping factor. The built in charger is often described on how many amps it will deliver. The watts of power that each "All in one" charger can use will vary based on system and design factors.


Note the images below from Watts 24/7 site, the 48v 3000w inverter will charge 80amps 4.5kw. The 24v 2.4kw inverter will also charge with 80amps but because of lower battery voltage, only 2kw. So your 5000watt inverter will have some sized charger in it. You need to dig out the specifications on that charger to help you understand the best panel setup for that charger. If you want more panels than the charger can use, you can get a second charger to charge the battery faster. This might be helpful on a sunny day if you want to pull high loads without draining the battery down, as more charger will keep up with the power going out of the battery better. So while the battery may be powering the inverter, if you can add power to the battery system as fast it is leaving the battery, you are in affect running off of the solar.....more or less.

1651146729190.png
 
was just curious if the panel set up max allowed is 3kw, and I don't want to drain the batteries, the max I can use is 3kw.
A 3kW array will probably maintain a 7kW or maybe as much as 10kW daily consumption if you’re using power while charging.
If I go over, the inverter will start using the batteries. Is that
Yes, but if the loads are intermittent that’s fine isn’t it? You’re building it to use solar power and battery voltage IS solar power
 
OK, so i am fairly clear on this all. Thanks.
The set up I have is 13 solar panels in series (345W, open circuit voltage 45.07V, current at Pmax 9.19A) with the above inverter
(https://powerpack.com.pk/wp-content/uploads/2020/07/sunglow-inverters-vm3000-user-manual.pdf)
: Max. PV Array Open Circuit Voltage 145Vdc 48V.

I have no batteries attached at the moment (I want 4 185AH tubulars - cannot afford them yet) and during the day when the grid is down, it powers my house fine. However at any point during the day without the grid, I cannot run my submersible pump.



The pump is 1.2kw rated pump. Our voltage here is 240V (grid)

This cannot run at any time during the day without the grid. When I run it, the inverter trips as overloaded. It recovers as soon after I swith off the pump. (the same overload message when I put too much load on it in the morning (juice machine, water heater etc)
 
13 panels in series x 45v would be 585v input and your max inverter PV input is 145v. That would be very bad.
 
13 panels in series x 45v would be 585v input and your max inverter PV input is 145v. That would be very bad.
I feel like i am going mad. I thought I read it recommended 13 panels in series in the manual.
As far as I am aware all of the panels are in series. 13 panels are odd, so i don't know what other configuration they could be in?

Would things not have blown up by now if it was that overloaded?
 
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