Brassburnz
New Member
Does this wiring provide protection to the inverter from the batteries? If so, could you explain? I placed my ANL fuse in between the positive bus bar and the inverter.
Want to build system to run fridge
- Thread starter rjmetals
- Start date
Well, I spot a fuse on the main battery line in the lower right corner.
Brassburnz
New Member
Is this configuration better than placing the fuse between the inverter and the positive bus bar, or does it not matter. I'm still trying to learn how the circuitry works. I figure it's better to ask questions than to do something incorrectly.
It is better. It protects the wire from the battery. It would probably be better in the battery, but it protects the wire from the fuse to the inverter just fine. Fuses should be sized to protect the wire. That is their purpose.
Hedges
I See Electromagnetic Fields!
- Joined
- Mar 28, 2020
- Messages
- 20,660
All that matters is fuse is in series with the current flow somewhere before a short that could occur. Usually we place it as close to battery positive as possible. A wire through metal bulkhead or exposed lug could short.
Between inverter and positive busbar protects against shorts in the inverter cable and inverter.
If you have separate SCC connected to busbar, it should have its own fuse also able to interrupt short-circuit current.
I estimate 20,000A from a lithium battery.
We'd like to have one fuse able to carry inverter current and interrupt max battery short circuit current, protecting smaller fuses downstream. But the current/time curves I've seen don't indicate it would. Copper wires of sufficient thickness will hold together long enough for the fuse to blow.
("Coordination" of tripping so bigger fuse/breaker is fast enough to protect smaller ones is part of the scheme for grid-fed AC, especially industrial locations where 200,000A is possible. The curves indicate protection there for smaller 20,000A rated parts. But not at 20,000A for 2000A rated parts.)
I think any fuses not rated 20k AIC, even if downstream of a class T fuse, should have a cover to protect you from them if they splatter.
Between inverter and positive busbar protects against shorts in the inverter cable and inverter.
If you have separate SCC connected to busbar, it should have its own fuse also able to interrupt short-circuit current.
I estimate 20,000A from a lithium battery.
We'd like to have one fuse able to carry inverter current and interrupt max battery short circuit current, protecting smaller fuses downstream. But the current/time curves I've seen don't indicate it would. Copper wires of sufficient thickness will hold together long enough for the fuse to blow.
("Coordination" of tripping so bigger fuse/breaker is fast enough to protect smaller ones is part of the scheme for grid-fed AC, especially industrial locations where 200,000A is possible. The curves indicate protection there for smaller 20,000A rated parts. But not at 20,000A for 2000A rated parts.)
I think any fuses not rated 20k AIC, even if downstream of a class T fuse, should have a cover to protect you from them if they splatter.
I placed fuse close to batteries between cut-off switch and batteries. I also placed breaker between bus bar and charge controller. I also placed 2-pole dc breaker between pv panels and charge controller to act as a disconnect switch.
Attachments
Last edited:
I like your circuit breaker and box for the solar input, do you have a link for the parts?
Both of the following were found on Amazon...
2P C65H-DC 250V 25A/40A Low-Voltage DC Miniature Circuit Breaker for Solar Panels Grid System White(40A)
uxcell Power Distribution Protection Box IP65 ABS Clear for Circuit Breaker Indoor on the Wall 5 Way (160mmx120mmx95mm)
I like it. That's a lot of work you did.....I know!
I just finished a ''solar generator'' cart for my son's house. He was out of power for 47 hours last year in August during the wildfires and heat wave. Running the Honda eu2000 generator every 8 hours was a chore. So now he can rig for silent running. Its on wheels and fits under his workbench. It has 8 of the Lishen 280AH cells in 12 volt configuration, 3000 watt inverter, 250 amp Daly BMS, Renogy Rover 30 amp MPPT solar input, an on board Aims 75 amp charger that can be plugged into his generator if needed. Its total is 7200 watt hours, 560 amp hours so it should run his fridge and freezer for a few days. There's an onboard Renogy 500 amp shunt battery monitor visible through the plexiglass top, 350 amp Blue Sea disconnect switch, and 100 amp isolation switches for the MPPT unit and the Aims battery charger.
I hardwired an outlet box with 15 amp outlets for the extension cord he will use. Its heavy duty and somebody would probably snag that cord if it were plugged in the inverter outlets. I try to make everything stupid proof. My guess on weight is 125 pounds. Tonight I added a panel with USB outlets, voltmeter, and 2 12 volt cigarette lighter outlets powered off the MPPT 12 volt load unit with a 20 amp circuit breaker in there for fun. A 50 amp Andersen plug allows him to plug in a roll of 10 gage wire. The solar panels will be temporarily set on his South facing patio roof. No permanent solar panel system will be installed just yet. In testing and beating on this cart, I have solar panels set up with the roll of temporary wire and MC-4 connectors. I have been running a 10,000 BTU window AC unit with it for free this week in this heat wave. I put 2700 watts load on with room heaters to check for any hot battery posts. Looks good so far. Everything is bolted down and secured with clamps and allthread. This unit could survive on its side or upside down with no damage. The MPPT is supposed to be wall mounted for ventilation but I put a 5 inch computer case fan under it. I can't feel any warmth on the cooling fins. It might not need it.
Attachments
Good morning Hedges,
When running parallel strings of PV panels, can one string have two panels and the other have three? Can the strings be unbalanced in count/power without causing problems?
Thanks again for all your help!
RJ
Hedges
I See Electromagnetic Fields!
- Joined
- Mar 28, 2020
- Messages
- 20,660
Unbalanced in current, power, even number in series would be OK if they are the same total voltage as another string.
I have 24, 120W Astropower in parallel with 12, 165W Sharp in parallel with 8, 327W SunPower.
All are very close to same Voc, around 480V and within a couple percent of each other.
If all panels are same model, all paralleled strings should have same number of panels in series.
I have 24, 120W Astropower in parallel with 12, 165W Sharp in parallel with 8, 327W SunPower.
All are very close to same Voc, around 480V and within a couple percent of each other.
If all panels are same model, all paralleled strings should have same number of panels in series.
How many temp solar panels?
Bud Martin
Solar Wizard
- Joined
- Aug 27, 2020
- Messages
- 4,843
Probably not many panels with Renogy 30A 12V MPPT setup, may be 400W worth of panels.
This is something that I just experienced with reviewing the amount of power needed for my deep freezer.
I had tested it during the Spring (mid 60s for highs) and it was using around 0.62 KWh per day.
Tested it this week (average in the mid 90s during the day) and it was at 2 KWh per day, so an increase of over 3 times what I had been forecasting.
Best way to test for a grid down, would be to turn off your AC, open all the windows to let the indoor temp stabilize, and then test whatever you are wanting to see the consumption of for a full day at least.
Good afternoon Hedges,
I have three Eco-worthy 195 W solar panels in series. MT50 shows I'm getting 350+/- W at my 40 A charge controller. Should I be getting more wattage?
Thanks!
Hedges
I See Electromagnetic Fields!
- Joined
- Mar 28, 2020
- Messages
- 20,660
3 x 195W (STC) = 585W (STC)
350W/585W = 60%
I think PTC rating of panels (output under full sun but normal operating temperature) is often 85% or so of STC.
What you don't know is if you have "one full sun", or somewhat attenuated by something in the atmosphere.
The days are getting a bit shorter, so just path length through air is longer.
So the output could be normal, due to sun/atmospheric conditions. Or it could be a bit less than expected.
Are the panels aimed directly at the sun?
Is battery voltage such that full bulk charging is expected?
350W/585W = 60%
I think PTC rating of panels (output under full sun but normal operating temperature) is often 85% or so of STC.
What you don't know is if you have "one full sun", or somewhat attenuated by something in the atmosphere.
The days are getting a bit shorter, so just path length through air is longer.
So the output could be normal, due to sun/atmospheric conditions. Or it could be a bit less than expected.
Are the panels aimed directly at the sun?
Is battery voltage such that full bulk charging is expected?
24V system. Bulk charging reaches a high of 28.8V per MT50 readings before charge controller backs it down.
Panels are not aimed directly at the sun. They are mounted on a flat patio roof. I hadn't considered angle to the sun. Shocked that the angle would make that much difference out here in the desert Southwest.
12VoltInstalls
life passes by too quickly to not live in freedom
It’s not the exposure- it’s the cross-section in square inches at 90* to the sun. Less exposure essentially
On the other hand, the math and actual practice do not always put up a unified logical front. I’m in Vermont- my panels have been vertical since last November and yet!! just this morning I was displaying 16.8A at 14.2V which is 238W with only the two SE-facing 100W panels ’exposed.’
Perfect alignment (or should I say lack of) often isn’t as high of a penalty as it would seem. Not that we should disregard that, either; the percent can be 15% - or a lot more depending on where you are located
Last edited:
Hedges
I See Electromagnetic Fields!
- Joined
- Mar 28, 2020
- Messages
- 20,660
I think this link says today the Sun's zenith is at zero degrees 41 minutes North.
If you're in Arizona, that would be about 34 degrees
latitudeandlongitude.org
sine(34 degrees) = 0.56
So it seems to me your PV output is greater than PTC rating times fraction of panel area presented to the sun.
Light reflection from the glass will vary with angle. Clouds will reflect additional light on the panels.
"Southwest" is a big area; try the math with your actual latitude.
If you can, tilt them at the sun for a test.
If you're in Arizona, that would be about 34 degrees
Arizona Latitude and Longitude - GPS Coordinates
Arizona Latitude and Longitude - get the gps coordinates of AZ and map coordinates. Arizona coordinates to find the latitude of AZ in decimal, degrees, minutes, and seconds.
latitudeandlongitude.org
sine(34 degrees) = 0.56
So it seems to me your PV output is greater than PTC rating times fraction of panel area presented to the sun.
Light reflection from the glass will vary with angle. Clouds will reflect additional light on the panels.
"Southwest" is a big area; try the math with your actual latitude.
If you can, tilt them at the sun for a test.
Similar threads
