I would highly recommend / endorse the Xantrex/Schneider XW series inverters, Mine ran a contractors 3hp floor sander for 3 days, before I figured out why the batteries were getting lower and lower during the day.. Contractor had to rent 2 different trailer generators to take the load off my system (when they were building the house).
In summer, it runs a 1,000 watt 240V pump for 4-5 hours a day for irrigation . Operation has been flawless . Generator support has been flawless. Firmware updates executed flawlessly,
It's been running 24/7 since mid 2010, with only planned outages, no surprise downtime. Eventually, it will cease operation and I will replace it with the latest XW model, likely the Pro series.
Batteries, plan on murdering your first set due to "unplanned events" Nearly always, during system shakedown, something happens and you find you under sized something to save money, and so you get to spend money twice. Unless you are a experienced power system engineer, it's going to happen. Feeling good does not make physics work, only natural laws.
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Thank you, Mike. I have a lot of questions.
The first one is kinda personal, about Inverters. I know your inverter is a hybrid. Do you recommend it? If it suddenly fails due to natural causes (lightning strike, etc.). Would you buy it again? If not, what would you buy?
The second is about batteries. But I’m not sure if I should ask here so I’ll create a new thread it in the Batteries forum. Thank you.
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Stick with flooded lead acid. Li batteries are still not ready for prime time.
Dump loads are only for wind or water turbines. Solar MPPT controllers do not use a dump load, they simply harvest only what they need. The inverter and controller need to be the same brand to simplify data communication and status control. (and of course rated for hybrid sell back use)
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Recommendations to grid-tie a small off grid system (with backup)
Greetings,
I have an off-grid system that was installed during an emergency. It’s a small system 24v (375ah) 2,480w PV and a 3kw inverter. I would like to grid connect the PV array (net metering). Currently considering a small string inverter 3kw (can I install a 5kw and use 1 or 2 string and expand later?) or micro inverters. I also would like to have battery backup (but not 100% sure).
If needed (because of hurricanes) the system will be off grid for months. Because of that I think an AC couple system is not ideal in these situations. Also, what I don’t like about AC couple is that (even with frequency shifting) an AC or DC dump load is highly recommended. That’s the reason why I partially in favor of a DC couple system.
I understand that for DC couple I need to buy a Hybrid Inverter. I would like to buy a dependable inverter (48v) and batteries. Most pro recommends AGMs or Lithium. What inverter and battery would you recommend (and why)? I you are an owner of a hybrid system, are you happy with it? Do you think it was worth the additional cost? Are they quiet (and do not have fans like most string and micro inverters)? Thank you very much.
PD: I have several, maybe unfounded, concerns. Some off-grid systems, mainly wind turbine, use dump loads (relays, not PWM regulated). I have heard that it is not recommended because you are basically micro cycling your batteries. My concern is that hybrid inverters use the excess voltage (production) to sell. Does that expose the batteries to micro cycles or to under/over charge situations (or voltages over absorption – AGM)? How the system behaves with lithium batteries? The charge controller needs to maintain the production (float voltage) for the inverter to sell. But as I understand, you are not supposed to float lithium. I know that lithium is compatible (according to the manufacturers). But it is recommended?
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