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Hello! Here is my quick introduction. In December 2020, we bought an off-grid cabin on the Olympic Peninsula, west of Seattle. The cabin has an existing DIY solar power system which seems to be basically sufficient to its use as a small vacation cabin. After experiencing six months ranging from famine (January) and feast (June) for solar power at this latitude, we are starting to put in place some plans to expand the existing structure and its power requirements, which is what brings me to this forum. We're still looking at this being primarily a weekend / vacation place for us for the next ten years or so, but once the kids are through college it'd be a nice place to retire to. 
Here's what exists today. 8 6V flooded batteries arranged into a 24V ~400 AH bank (four of these, one series string, are aging Trojan T-105 batteries, the other four are less expensive Costco Interstate GC2 batteries of similar capacity that replaced the other 4 T-105 batteries which already failed). Outback FX2524T inverter mounted on a Midnite E-panel. Midnite Classic 150 charge controller. Trimetric battery monitor. And, an array of mismatched solar panels with a combined nameplate rating of about 2000W. The Vmp on these ranges from 25V to 36V and they are (well, were) all wired in parallel. The array output has never come close to 2000W, but I have been able to get it up to 900W by using a Trace C40 PWM charge controller that previous owners left behind to create a separate sub-array for the 25Vmp panels, leaving the higher voltage panels on the Midnite. There are two back-up generators, a Winco 8 kW 120/240V propane generator and a Craftsman 6.3 kW 120/240V gasoline generator, but this Outback inverter seems only to handle 120 V, so I don't think I can use more than half of either generator's output. The entire cabin is wired with a single leg of 120V, as well as 12VDC (via a 24/12 DC transformer) for phone charging/lights without requiring the inverter to be on. Haven't worked out my load requirements in detail yet, but for the last few months we've had no problem charging phones and laptops and running a small refrigerator entirely on solar/battery power -- according to the Trimetric we're typically down about 80 AH when the sun comes up and we begin charging again. The well has a Grundfos SQF 2.2 GPM pump which fills a 1000 gallon tank at the top of a hill and has been perfectly happy running off the inverter. Gravity provides us adequate water pressure.
The project we are looking at now is installing septic. Unfortunately, due to the soil and site conditions, local regulations will require a powered pressurized drainfield. Our septic designer has an excellent reputation for creating designs for challenging sites, but has limited experience designing for off-grid power. The current design specifies a 1/2 HP 120V Orenco effluent pump which has a 12.5A fully-loaded current draw but a 64.4A locked-rotor draw. The Outback inverter's specs say it can surge only up to 50A, so it looks like this isn't going to work without some design changes or system upgrades, and I've been reading over this site to get an idea of what to do about this, as well as how to grow (or more likely, progressively replace) the power system for our future use.
Anyway! Maybe this got a little long for an intro, happy to break some of these out into separate topics in the off-grid forum (especially our interesting panel configuration -- taking that apart, measuring its output, and putting it back together has been highly educational for me to understand how solar panels actually work).
Here's what exists today. 8 6V flooded batteries arranged into a 24V ~400 AH bank (four of these, one series string, are aging Trojan T-105 batteries, the other four are less expensive Costco Interstate GC2 batteries of similar capacity that replaced the other 4 T-105 batteries which already failed). Outback FX2524T inverter mounted on a Midnite E-panel. Midnite Classic 150 charge controller. Trimetric battery monitor. And, an array of mismatched solar panels with a combined nameplate rating of about 2000W. The Vmp on these ranges from 25V to 36V and they are (well, were) all wired in parallel. The array output has never come close to 2000W, but I have been able to get it up to 900W by using a Trace C40 PWM charge controller that previous owners left behind to create a separate sub-array for the 25Vmp panels, leaving the higher voltage panels on the Midnite. There are two back-up generators, a Winco 8 kW 120/240V propane generator and a Craftsman 6.3 kW 120/240V gasoline generator, but this Outback inverter seems only to handle 120 V, so I don't think I can use more than half of either generator's output. The entire cabin is wired with a single leg of 120V, as well as 12VDC (via a 24/12 DC transformer) for phone charging/lights without requiring the inverter to be on. Haven't worked out my load requirements in detail yet, but for the last few months we've had no problem charging phones and laptops and running a small refrigerator entirely on solar/battery power -- according to the Trimetric we're typically down about 80 AH when the sun comes up and we begin charging again. The well has a Grundfos SQF 2.2 GPM pump which fills a 1000 gallon tank at the top of a hill and has been perfectly happy running off the inverter. Gravity provides us adequate water pressure.
The project we are looking at now is installing septic. Unfortunately, due to the soil and site conditions, local regulations will require a powered pressurized drainfield. Our septic designer has an excellent reputation for creating designs for challenging sites, but has limited experience designing for off-grid power. The current design specifies a 1/2 HP 120V Orenco effluent pump which has a 12.5A fully-loaded current draw but a 64.4A locked-rotor draw. The Outback inverter's specs say it can surge only up to 50A, so it looks like this isn't going to work without some design changes or system upgrades, and I've been reading over this site to get an idea of what to do about this, as well as how to grow (or more likely, progressively replace) the power system for our future use.
Anyway! Maybe this got a little long for an intro, happy to break some of these out into separate topics in the off-grid forum (especially our interesting panel configuration -- taking that apart, measuring its output, and putting it back together has been highly educational for me to understand how solar panels actually work).
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