Portable AC Power

When the battery(s) fail in a UPS, I replace it with an appropriate sized flooded battery, group 24/31 etc. Depending upon the load the UPS will run for several hours. If the outage is going to be longer,. (downed lines etc), I disconnect the UPS and use an appropriate sized inverter. UPS, because of their advanced circuitry are quite inefficient. Inverters on the other hand, unless it is a high end unit, have MTBF of less than 100 hrs. Mean Time Between Failure.

I had a 600 watt pure sine wave, it failed after 200 hrs of continuous use. The most it ever saw was 400 watts. That is how I found out about the MTBF. Now I have 2 1500 el cheapos from Costco. I also have a Ryobi 1800/2300 watt inverter. I had to replace the "inverter" at 850 hrs. I had it wired into the house. The manual states not to ground it. I'm looking for a 120 to 240 center tapped 3K transformer to solve that issue. If anyone knows......... I also have a 3500/4200 B&S 240-20amp. This will run 1 A/C unit. But it uses 4 gallons a day and is quite noisy. I'm going to build an external muffler to solve the noise. I have a spare head and can replace the resulting burned valves in under an hour. (Don't ask how I know this and nor I have a spare head). Lost power Sept 6 2017 got it back mid March 2018. Solar is nice, but they don't like cannon ball sized  coconuts.

I weathered 4 hurricanes and 1 strong tropical storm last season. I had my share for the next 10 years. Lol. But it pays to be prepared!

After the divorce, I plan to buy 3 5kw inverters and 9 kw of solar panels to feed them. My buddy has this system and uses net metering for his grid intertied system. It furnishes all of his power needs for his 2400 sf house, 2400 sf shop, and his in ground swimming pool pump. The down side is that it shuts down when the grid is down. I'm considering a hybrid system. Maybe 2 inverters on the grid and the third solar array will feed a UPS with the most critical loads. (refrigerator, a minisplit, etc.... I work on UPS' for a living and can often get free used batteries. I need to find a UPS that can accept solar input or just get an off grid inverter fed from solar charged batteries and include a break before make bypass to utility if I have inverter problems.

I wonder if I could parallel all of the DC arrays together with grid actuated contactors so that the on grid arrays would also feed the off grid inverter in the event of a power outage and run separately otherwise. I hate that the on grid system is useless during a power outage.

Crusader wrote:After the divorce, I plan to buy 3 5kw inverters and 9 kw of solar panels to feed them.  My buddy has this system and uses net metering for his grid intertied system.  It furnishes all of his power needs for his 2400 sf house, 2400 sf shop, and his in ground swimming pool pump.  The down side is that it shuts down when the grid is down.  I'm considering a hybrid system.  Maybe 2 inverters on the grid and the third solar array will feed a UPS with the most critical loads. (refrigerator, a minisplit, etc....  I work on UPS' for a living and can often get free used batteries.  I need to find a UPS that can accept solar input or just get an off grid inverter  fed from solar charged batteries and include a break before make bypass to utility if I have inverter problems.

I wonder if I could parallel all of the DC arrays together with grid actuated contactors so that the on grid arrays would also feed the off grid inverter in the event of a power outage and run separately otherwise.  I hate that the on grid system is useless during a power outage.

I think you could easily do it , Tex. There are advantages to both but if you have access to cheap or free batteries, I'd go offgrid with storage. Backup generator just in case . You're far enough inland where hurricane force winds shouldn't be a problem for any size array.

Crusader wrote:After the divorce, I plan to buy 3 5kw inverters and 9 kw of solar panels to feed them.  My buddy has this system and uses net metering for his grid intertied system.  It furnishes all of his power needs for his 2400 sf house, 2400 sf shop, and his in ground swimming pool pump.  The down side is that it shuts down when the grid is down.  I'm considering a hybrid system.  Maybe 2 inverters on the grid and the third solar array will feed a UPS with the most critical loads. (refrigerator, a minisplit, etc....  I work on UPS' for a living and can often get free used batteries.  I need to find a UPS that can accept solar input or just get an off grid inverter  fed from solar charged batteries and include a break before make bypass to utility if I have inverter problems.

I wonder if I could parallel all of the DC arrays together with grid actuated contactors so that the on grid arrays would also feed the off grid inverter in the event of a power outage and run separately otherwise.  I hate that the on grid system is useless during a power outage.

In NZ the supply companies will buy your excess power from you, but give you virtually nothing for it, they have your hot water cylinder hooked up to a controlled system so the can shut it down during times of high demand and restrict you to heating it in off peak

vege57 wrote:

Crusader wrote:After the divorce, I plan to buy 3 5kw inverters and 9 kw of solar panels to feed them.  My buddy has this system and uses net metering for his grid intertied system.  It furnishes all of his power needs for his 2400 sf house, 2400 sf shop, and his in ground swimming pool pump.  The down side is that it shuts down when the grid is down.  I'm considering a hybrid system.  Maybe 2 inverters on the grid and the third solar array will feed a UPS with the most critical loads. (refrigerator, a minisplit, etc....  I work on UPS' for a living and can often get free used batteries.  I need to find a UPS that can accept solar input or just get an off grid inverter  fed from solar charged batteries and include a break before make bypass to utility if I have inverter problems.

I wonder if I could parallel all of the DC arrays together with grid actuated contactors so that the on grid arrays would also feed the off grid inverter in the event of a power outage and run separately otherwise.  I hate that the on grid system is useless during a power outage.

In NZ the supply companies will buy your excess power from you, but give you virtually nothing for it, they have your hot water cylinder hooked up to a controlled system so the can shut it down during times of high demand and restrict you to heating it in off peak

We have "net metering" for solar production in most of Texas. The meter runs both ways and we settle the difference at the end of the month. Some power companies let you carry over excess energy production to the next month and settle up at the end of the year. If you make excess and actually sell power to them, it's at the cost of their production (usually about $.025/kwh), but the perk is that you don't have to pay for batteries and all of the extra safeguards that come with an off grid system.

Shut down circuits can be bypassed.

HawkTheSlayer wrote:

Crusader wrote:After the divorce, I plan to buy 3 5kw inverters and 9 kw of solar panels to feed them.  My buddy has this system and uses net metering for his grid intertied system.  It furnishes all of his power needs for his 2400 sf house, 2400 sf shop, and his in ground swimming pool pump.  The down side is that it shuts down when the grid is down.  I'm considering a hybrid system.  Maybe 2 inverters on the grid and the third solar array will feed a UPS with the most critical loads. (refrigerator, a minisplit, etc....  I work on UPS' for a living and can often get free used batteries.  I need to find a UPS that can accept solar input or just get an off grid inverter  fed from solar charged batteries and include a break before make bypass to utility if I have inverter problems.

I wonder if I could parallel all of the DC arrays together with grid actuated contactors so that the on grid arrays would also feed the off grid inverter in the event of a power outage and run separately otherwise.  I hate that the on grid system is useless during a power outage.

I think you could easily do it , Tex. There are advantages to both but if you have access to cheap or free batteries, I'd go offgrid with storage. Backup generator just in case . You're far enough inland where hurricane force winds shouldn't be a problem for any size array.

Off grid has a lot more safeguards and expenses.  You need a charge controller, batteries, a generator for backup, and a way to bleed off excess energy if you make more than you can store in the batteries.  I want to do a hybrid system, which is even more complex, but a grid tied system with net metering is so easy and simple.  You also have the added responsibility of fixing the system if it should break. An on grid or hybrid system would at least allow you to install a bypass to make repairs more manageable.

I can get a cheap battery cabinet that will hold 40 12V 150AH batteries and over time I can get decent used batteries to fill it for free.  The cabinet is not much bigger than a refrigerator and has slide out trays with 4 batteries each.  It can be wired for whatever voltage you need.  Today and tomorrow, I am replacing 160 batteries, but they are all 6 years old and not much good for anything but recycling at this point.  I'd really like to find a small wet cell system like they use to back up switch gear controls.  Those are 20 year batteries.

Yep. Keep the battery cabinet charged. Use it when you wish and return the rest to the grid to lower costs.

Good deal.  I'm looking at some panels for my roof and some storage capacity too.

HawkTheSlayer wrote:Yep. Keep the battery cabinet charged. Use it when you wish and return the rest to the grid to lower costs.

Good deal.  I'm looking at some panels for my roof and some stove capacity too.

The batteries I get are fickle.  They are ideally kept at a constant voltage and in a cool environment.  They wouldn't do very well with daily discharge and recharge cycles.  They might last a year that way.  My hybrid system would allow you to keep the batteries on constant charge and switch to solar charging only during power outages by switching the solar panels from the on grid inverters to a charge controller for the batteries during the outage.  For daily use, the solar panels would feed the on grid inverters to keep the meter from spinning.

I want a wood burning stove. A preheat tank for the water heater with a heat exchanger to get heat from the stove exhaust is a thought. Thanks for the idea.