mcgivor ✭✭✭✭


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  • Re: GE washing machine won't run off inverter power

    Aluminum has a tendency to displace under screw terminals over time, good idea is to re torque after initial installation just to be sure. 
  • Re: Sunedison 320w

    Technically there is no limit but as the number of parrallel strings increases so dose the potential to have imbalances in the charging and dischargeing currents which can cause some strings working harder than others, leading to premature failure. There are different schools of thought but the general consensus is keep it to a minimum, two or perhaps three, despite it being possible to achieve ballance with more. If there is a need to increase capacity beyond this, it's better to use larger capacity batteries. Another thing to be aware of, its not good practice to mix old with new batteries, unless pretty close in age and lightly used. This link is commonly referred to and explains the theroy and how to connect to achieve better ballance
  • Re: Time spent in absorption.

    In addition to Rick's valuable information, it's important to remember if there are any loads present the end amps feature may be offset by whatever the load draws, generally about 2% of battery Ah capacity is the normal setting, intermittent loads such as a refrigerator cycle so do not generally cause issues, just constant ones. The Absorb timer will terminate the absorption regardless of the end amps setpoint, so the timer setting is largely governed by the arrays capacity to provide enough energy, smaller wattage array  will require more time. In addition seasonal adjustments my be required to compensate for lower output, so it's really a custom setting which must be observed over time to find the sweet spot. FWIW, my controller has a default absorption time of 180 minutes adjustable in custom settings, end amps fixed at 2% of entered battery capacity and recharge at 25v should the float value drop below that setpoint, again custom adjustable. For the most part it works fine at default values but during the rare extended cloudy periods I have, I simply extended the time to 240 minutes, as long as your PV can supply 10% of the rated Ah capacity in charging current these values may be a good starting point.
  • Re: Battery sizing for 600W panels

    The 5-13% rule of thumb is a guideline, the lower rate being for occasional use such as a weekend cabin, the higher for full time off grid, in reality it really comes down to the loads present when there is no PV input. A calculation of the actual loads during no input is the most important figure of the equation, in order to determine what would be required to replenish what's taken out. So as an example the 450 Ah battery is discharged by 45Ah or 10%, the 600W array would produce 600W × 0.8 = 480W, 480W ÷ 14.4 V = 33.3A, now assume you have 3 hours of peak sun, there is approximately 100Ah available, enough to cover the withdrawal from the battery bank, including losses by a margin of~50% . It's always better to design with reserve capacity rather than being close to what the actual consumption is. The answer to your question, is a 600W array enough to keep 4 × 6V 225Ah batteries fully charged is, yes, as long as the loads do not exceed the array's ability to replenish withdrawals and losses by a healthy margin, to cover the days of reduced PV output. Just a non technical explanation since the question is in beginners corner. 
  • Re: New setup off grid camper

    The 24V opinion would be the best choice, given the panel's 47.6 Vmp, MPPT would be the only option, a single 60A controller would be a good fit as the voltage is close to double battery nominal which is perfect. PWM needs the Vmp to be close to the nominal battery voltage, usually around 36V for a 24V system, although a PWM  controller may be able to support 48V, there will be losses which manifest as heat, MPPT down converts the higher voltage convertin it to current, hence more efficiency.