help 2kw sine wave invertor, will it kill my battery and me ?

[johnbythesea]

Okay I need a little help!!! This is the first time I have done this !!!!

I'm installing a solar system, its a 12v system. I have 4 x 150w solar panels, a charge controller (50 amp) a 145 amp battery and a 2kw invertor. It was never my intention to get a 2kw invertor, i was simply given it as a replacement to the 1500w one which was out of stock.

I know I have more w from the pannels than is needed for the battery, i think 400w is about optimum, I'm going to install anyway and at a later date add another battery or remove a panel.

my question is about the invertor, 2kw is a lot of power to draw from the 145amp battery, will it do this regardless or is it dependent on what appliance I am using. for example, if i use the 2kw invertor to charge a mobile phone will it draw out the same power from the battery as if i used a 1500w or 1000w invertor or because its a 2kw it will draw more power regardless ?

I don't have any option of increasing my battery at present as its dependent on weight and that's the best battery i can fit in, this will change in the future.

Any other feadback on my system? is it a fire risk?

Also my invertor has a set of 35amp fuses on the back, i'm assuming this means i doesnt need to install another fuse into invertor as it is already inbuilt ?

feedback much appriacited, as this is giving me a headache.

cheers
john

[mapmaker]

It was never my intention to get a 2kw invertor, i was simply given it as a replacement to the 1500w one which was out of stock.
<snip>
my question is about the invertor, 2kw is a lot of power to draw from the 145amp battery, will it do this regardless or is it dependent on what appliance I am using. for example, if i use the 2kw invertor to charge a mobile phone will it draw out the same power from the battery as if i used a 1500w or 1000w invertor or because its a 2kw it will draw more power regardless ?

Welcome to the forum,

Generally, the larger the inverter, the less efficient it is at handling small loads. What model and brand of inverter is it?

--mapmaker

[johnbythesea]

thank you

it doesn't appear to have any info on it as to what the make or model is... i know its modified, I can post a link to the page its sold on?

the tec info is:



2000W 12V to 230V Pure Sine Wave Inverter for running all types of appliances using 230V volts including computers and appliances with timer mechanisms.

The Inverter has a 2000W continuous output with an initial double surge capacity at 4000W

Technical Detail:

DC Input Data
Input voltage: 10-15V
Low Voltage Alarm: 10.5V
Low Voltage Shutdown: 10.0V
Overvoltage Shutdown: 15.0V
Efficiency:>90%

AC Output Data
Surge power: 150% Rated Power 10s, 200% 2s
Output Waveform: Pure Sine Wave
Output Voltage: 230V
Output Frequency: 50Hz
Output Voltage: 230V
Continuous Power: 2000W
No Load Current Draw: <0.6A

Protective Features
Over Thermal: Shuts off output automatically when temperature >75°C
Short Circuit protection: Reverse polarity (external fuse)
Cooling Fan: Automatically runs when temperature ≥45°C
Working temperature: -10°C to +50°C
Dimensions: 430 x 286 x 168mm
Weight: 6.0Kg
Spare Fuses: Four
Warranty: One year

[mapmaker]

No Load Current Draw: <0.6A

That's an important number. 12 volts X 0.6 amp = 7.2 watts

Your inverter will draw 7.2 watts by just being turned on (tare loss). That may be more than the cell phone charger uses!

On the other hand, that is a pretty low number for a 2000 watt sine wave inverter.

--mapmaker

[johnbythesea]

got it... and thank you, that's one question off my mind, not as bad as I had first thought, but not ideal

I've suddenly come across another worry. I'm depressed. shade, how can you tell if the solar panels have bypass diodes and are protected?. I have a feeling they aren't.


As the system is going on top of a motorhome, its going to be part shaded when parked. Ill have to open the circuit when parked, grrrr can you have a look at the panels and tell me if you think they are protected or not ?

http://renytek.co.uk/p/244/semi-flexible-solar-panels

thanks for this. wish i had found this forum before my partner bought the pannels.



john

[mapmaker]

how can you tell if the solar panels have bypass diodes and are protected?.

As the system is going on top of a motorhome, its going to be part shaded when parked. Ill have to open the circuit when parked, grrrr can you have a look at the panels and tell me if you think they are protected or not ?

I think you are referring to blocking diodes, not bypass diodes. Blocking diodes prevent your battery from discharging into the panels at night. You do NOT need them... your charge controller will provide that function.

Bypass diodes allow a panel to produce some power when it is partially shaded.

--mapmaker

[johnbythesea]

no i'm thinking of bypass diodes, i've heard with out them your panels with damage over time if in partial shade. grrrrr, am i over worrying ? i have a habit of doing that

[mapmaker]

no i'm thinking of bypass diodes, i've heard with out them your panels with damage over time if in partial shade. grrrrr, am i over worrying ? i have a habit of doing that

1) I'm not aware of any damage to the solar cells caused by lack of bypass diodes

2) Partial shading makes the bypass diodes conduct, which may stress them... I have heard of bypass diodes burning out from partial shading.

3) Your panels seem to be true 12 volt panels (not grid tie panels) and can be used with a PWM type controller. A bypass diode works by bypassing a group of solar cells in the panel. At the low voltage of your panels, if there were bypass diodes and if they were conducting, the resulting voltage would be too low to charge your battery. On higher voltage panels with MPPT controllers, if there is partial shading, the voltage may still be high enough to get some usable power. I think that with your panels any shading will mean you get no power.

--mapmaker

[inetdog]

Also, for what it may be worth, 600 watts of PV (50A at 12V) is far more power/current than you should use to charge a 145 amp-hour flooded lead acid (FLA) battery.
You should not try to put more than about 20 into it to avoid overheating and plate erosion.
Now if you have a 145AH AGM type sealed battery, you might be OK with 50A.
If it is a GEL type sealed battery (not terribly likely) you should not be using it at all for solar PV.

[johnbythesea]

the battery is a 12V 145AH Sealed Valve Regulated Deep Cycle Lead-Acid Battery.

spec is, im thinking of down grading to a 330w system

Manufacture Alphaline
Volt 12
AH 145AH
Length (mm) 512
Width (mm) 189
Total Height (mm) 225
Weight (kg) 35
Layout RH+
Terminal A Terminal
Application Deep Cycle

[Sunking]

OK you have things quite a bit out of balance. To start with a 2000 watt inverter screams for 24 or 48 volt battery voltage. 12 volt systems should be limited to no more than 1000 watts.

Second the inverter wattage should be no greater than panel wattage using MPPT controllers.

On a 12 volt system using PWM controllers the voltage to AH ratio on the low end 1.5 watts for every 1 AH of battery. On the high end 2.25 volts per AH. MPPT is quite a bit more efficient so the ratios are lower so at the low end 1 volt per AH and on the high end 1.5 volts per AH. You have a 145 AH battery so figure it out.

With that being said your battery is a AGM Cranking battery with a CCA = 1000 amps which tells us the internal resistance is around 9 to 10 milli-Ohms. Assuming a 100% DOD battery the maximum charge current that can be applied is around 80 to 100 amps. So as long as you stay below that the battery is in no real danger, but your wiring could be if not sized correctly and attention to details in with Instalation.

80 to 100 amps is also the maximum discharge rate for this battery, and this is where you could have trouble with an over sized inverter. At 2000 watts requires roughly 200 amps from the battery. Once your battery hits about 100 amps its voltage will drop to 11 volts, add another .5 to 1 volt drop on the cables and connectors and the inverter input voltage is less than 10.5 volts and trips off line from under voltage.

Ideally for a 2000 watt 12 volt inverter the minimum battery requirement is 1600 AH or over 10 times what you have. It would also require a 2000 watt panel wattage and 2 very expensive 80 amp MPPT controllers. Thus is why for a 2000 wat inhverter requires a minimum of 24 volt 800 AH battery, or 48 volt 400 AH battery.

[Shockah]

Question: What are you powering with that inverter/battery/panel combo?

Might simply be cost effective for you to pawn off that 2K and get a correctly sized one.

[mapmaker]

Question: What are you powering with that inverter/battery/panel combo?

Might simply be cost effective for you to pawn off that 2K and get a correctly sized one.

It is explained in the first post in this thread.

--mapmaker

[johnbythesea]

OMG I've made such a massive mistake, i'm going to have to return the panels and invertor, I know the guy who sold them to me is going to be pissed off and try to argue with me.

Ok, the design will now be

330w panels with 145amp batteries and 350w invertor. I will keep my amp charge controller.

it is to power two laptops, two mobile phones, and two 11w lights... ekkk!!!

[Shockah]

It is explained in the first post in this thread.

--mapmaker

Mobile Phone?! That's it?

Maybe the OP is planning on more use...

it is to power two laptops, two mobile phones, and two 11w lights... ekkk!!!

Ah yes, there is the actual usage.

Now you need to get a Kill-a-Watt and determine the total watts those laptops use in 24hours.