The first few days running my system

micahvmicahv Registered Users Posts: 17
Well, it has been a few days now of powering a circuit in my house with my PV system.

My PV system consists of
1 Sure Sine 300 Inverter
1 Morningstar MPPT Sunsaver
1 205W kyocera Module.
2 6V Costco golf cart batteries....totalling 2400WH I think...haven't verified this.


-- 4-14 hours, light only at night, so peak usage can exceed max power from module---
Comp. Room ceiling light 13W
Laptop 50W/ 6W in standby
Network(router/modem) 11W

--15-30 minutes---
Bedroom ceiling light 60W - disconnected now till I find CFL replacement
Bedroom floor light 13W

--30 minutes---
Bathroom light 23W

--1-3 hours a night--
TV Room floor light 13W
TV and DVD 90W

Tends to be either laptop or TV....

I know I need to get the TV off this circuit. First the inrush power exceeds my inverter I assume as when I turn it on it clicks a few times and the lights flicker before it powers on. I can turn it on and off for a while afterward with no issue, I assume due to capacitors or something still being charged. Is there an easy way to measure this inrush current? Do clamp on meters do good at this? I try to turn everything else off on the circuit before powering on.

My wife has been using the laptop a lot for a school project...75W(laptop and light) If not on the laptop then watching TV(103W with light).

I have had one LVD I'm sure more will occur with the winter months and cloudier days. had one fairly overcast day.

I also discovered one LED on my charge controller is burned out(red low voltage)....but also find I really need more granular battery monitoring capability. Green LED for nearly full to Yellow for half full, to Red for Battery low. These are all kind of vague. When I talked to morning star, I think he said red,yellow implies bulk and then green is about 80% still bulk and then green flashing in 90% absorption charging(haven't got there yet :)) I wrote it down but lost it...think that is what he said though. So yellow could be approching 50% soc to 80% soc, thats a huge cool if they just made the yellow flash faster as it approached 80%(green).

I tried running the inverter in standby mode to conserve a little more power, but something are funny with this...alarm clock still kind of powers on even though inverter is in standby. I guess since the inverter is pulsing AC in the circuit to check for load greater then 8W every 1 second this is enough to keep my clock kind of running(keeps time, but the display keeps flashing on and off) Think the laptop also gets power when in standby. This kind of concerned me that some electronics trying to be on getting this funky power pulse. So I turned off standby mode...Figured self consumption when AC is on is only 5-6W so standby not saving me to much there, maybe 50W/day...thats an hour of laptop time!.

I still need to get a rack solution. Right now I kind of got it self-ballasting....filled some milk crates with rocks and tied the panel to the milk crate using some aluminum angles. Also, tied down with rope....very temporary..anyone got some basic plans for a simple single panel roof mount, adjustable tilt preferably..


  • BB.BB. Super Moderators, Administrators Posts: 32,006 admin
    Re: The first few days running my system

    My guess is that you are drawing way too much power from a 200 watt panel + a pair of batteries.

    Using the PV Watts website for Forth Worth Tx, 1kW of solar panels (smallest program allows) and 0.52 derating :
    "Station Identification"
    "Lat (deg N):", 32.83
    "Long (deg W):", 97.05
    "Elev (m): ", 164
    "PV System Specifications"
    "DC Rating:"," 1.0 kW"
    "DC to AC Derate Factor:"," 0.520"
    "AC Rating:"," 0.5 kW"
    "Array Type: Fixed Tilt"
    "Array Tilt:"," 32.9"
    "Array Azimuth:","180.0"

    "Energy Specifications"
    "Cost of Electricity:"," 9.7 cents/kWh"

    "Month", "Solar Radiation (kWh/m^2/day)", "AC Energy (kWh)", "Energy Value ($)"
    1, 4.32, 66, 6.40
    2, 4.77, 66, 6.40
    3, 5.50, 82, 7.95
    4, 5.98, 85, 8.25
    5, 6.02, 86, 8.34
    6, 6.25, 84, 8.15
    7, 6.39, 87, 8.44
    8, 6.31, 86, 8.34
    9, 5.83, 78, 7.57
    10, 5.56, 80, 7.76
    11, 4.43, 65, 6.30
    12, 4.10, 63, 6.11
    "Year", 5.46, 929, 90.11

    For November, 65 kWhrs per month per 1kW of solar panels. For you 0.205 kWatts of panels per 30 day month:

    65kWh/mnth per 1kW of panels* 1mnth/30 days * 0.205kW/1 kW of solar panels = 444 Watt*Hours avg of 120 VAC power per day

    Just 10 hours of laptop+lighting per day is already exceeding the average available power per day.

    Also, you may have the 24kWHrs of battery wrong... If you have 2x 6 volt 100 AH batteries (just guessing)... When you put batteries in series, the voltage doubles and the AH stays the same:

    12 volts * 100 AH = 1,200 Amp*Hours

    And, it is recommended that you don't cycle the batteries below 50% state of charge on as normal usage (for longer life):

    1,200 Watt*Hours * 50% = 600 Watt*Hours of useful storage at 12 volts

    Yes, I believe the inverter is "standby" is checking every few seconds if there is >8 watts of AC load out there (or whatever their particular power limit is). In theory, should not damage anything--but if you have small motors or other devices that don't like power cycling--may not be good for them (some AC power supplies may not like their AC power turned on/off every 10 seconds either as surge current stresses them--I don't know if that is an issue with your setups--too many variables to make a call).

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarusicarus Solar Expert Posts: 5,433 ✭✭✭✭
    Re: The first few days running my system

    You've got way too much load.

    On 4 T 105 golf cart batteries (~450 ah/12vdc) we will only draw them down ~60- 80 ah/day, (less than 20%) and no running loads of more than about 6 amps/ 12vdc (72 watts)

    My rule of thumb, easy napkin calculation takes the name plate rating of your panels (205 watts) divide it in 1/2 to represent ALL the cumulative system loses (Pv/wiring/Charge controller/basic battery charging ef/inverter/line loss) then take that number and multiply it by the average number of hours of GOOD sun, seldom more than ~4, giving a total useable power out the outlets per day.

    So 205/2=102.5X4=410 wh or ~36 ah.

    So you can easily see that you are exceeding your systems capacity.

  • KamalaKamala Solar Expert Posts: 452 ✭✭
    Re: The first few days running my system

    I think Bill & Tony are correct about your loads.

    Regarding the inverter standby problem. I am not familiar with the SureSine, But I can tell you that my ProSine load sense function does not work in my setup. According to the ProSine manual, the problem lies with electronic devices that present "phantom loads." I have a LCD TV and a microwave oven on the circuit. No matter which load sense threshold I select (10-200W) the inverter cycles on and off.

    My solution was to disable the load sense function and use the control panel to enable (25W) or disable (0.5W) the inverter as needed. I also installed the remote shut down switch (probably not available on the SureSine) so that I can effectively turn the inverter "off" when not in use. Power consumption in this condition is 0.024W.

    Good luck!

  • icarusicarus Solar Expert Posts: 5,433 ✭✭✭✭
    Re: The first few days running my system

    The Suresine's threshold to come awake is ~ 8 watts if memory serves correctly. That said, it will carry an ac load as low as ~2-3watts. Every once in a while I am surprised that my .05 watt LED back porch light is still on, only to discover that I have a 3 watt cfl burning in the office that I forgot to turn off.

    The Suresine does have remote switching capability, so you can just shut it off.

  • dwhdwh Solar Expert Posts: 1,341 ✭✭✭
    Re: The first few days running my system
    micahv wrote: »
    Is there an easy way to measure this inrush current? Do clamp on meters do good at this?

    No, not really.

    The better quality meters, such as some of the Flukes do, but they have to be designed for it.

    One of the forum regulars here, 2manytoyz went out and bought a good Fluke just for that. I don't remember which one, but you can check his site and probably find out:
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