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diy solar

Looking for a 1500W Output UPS Capable Solar Generator that is SILENT in AC Pass-through

RLevine

New Member
Joined
Mar 18, 2025
Messages
3
Location
Florida
I have been a very long-time user of Cyberpower UPS units, but long wanted to switch to a lithium chemistry based system for the increased power density and run time.

The TLDR is that I want a solar generator that: 1) can output 1500+ watts; 2) has a reliable 10-20ms UPS-like transfer when the power goes out or the home voltage drops to around 115v; 3) is absolutely silent when in AC pass-through on wall power; 4) properly operate in a room with a noise ceiling of 25db with all noise making objects measured at a distance of under three inches (7.62 cm) from the objects; and 5) just to be clear not make any noise while acting as a still-plugged in UPS.

Back in the summer of 2022, I was looking for lithium battery info on youtube to have a small battery backup for the hurricane season that would last powering my kitchen fridge and possibly a one-room portable AC during a power failure until it was safe to fire up a portable gas generator. At the time, I was impressed by the Vigorpool Captain 1200 for being able to put the inverters in parallel so as to power any portable cooking appliance and readily fire up a medium-office scale laser printer... so I ordered a pair along with the parallel cable.

Although the Vigorpool units performed exactly as advertised, including having a great UPS transfer and load splitting when in parallel operation, I ended up being unable to replace my aging rackmount Cyberpower UPS because the Captain 1200s while in AC pass-through mode are not truly pass-through and the obscenely, obnoxiously loud fans frequently spin up even when the units are on standby with temperature readings of under 20C! Rather than real pass through like most old-fashioned lead acid based UPS companies, power trickles into and out of the Captain 1200's batteries while the inverter is on and that is almost constantly setting off their fans.

Because of that, I went back to using my rackmount Cyberpower system since it makes no noise unless and until the power goes out or voltage drops (because the county water company has pumps in the neighborhood that don't play nice with FPL's power lines). Unfortunately, and after "only" nine years of service, one of the batteries in the Cyberpower system has died.

I need truly quiet system while still receiving regular wall outlet 120v power. Making appropriate noise is fine when the power goes out, but in all other circumstance silence is vital.

Would like recommendations for any portable-ish all-in-one that fits my use requirements or alternatively battery / inverter / rectifier parts list that will also cover my silent UPS needs without being reliant on bluetooth or Wifi to work.
 
Lifepo4 is not ideal for this task. While it's great for solar, home power systems, it does not shine in UPS applications. You are better off selecting a different chemistry for this purpose.

LIfepo4 is best stored at 30-50% SOC, and that's effectively what you're doing. You're storing it, ideally at 100% SOC, for however long it is between power outages.

Cyberpower is the shit tier of UPS's. I would recommend tripplite as 2nd to APC, which is top tier, but not by much other than price. I was using 6 tripplites for the decade before my off-grid switch.
 
I don’t know about the rest of them but the EF delta2 fans run even when powering a 70w lightstrip. Stay away from them if you want silence.

Why not dyi? Depending on size requirements it shouldn’t be too difficult or expensive. Instead of solar panels just charge it from the grid.

You specify 1500w. How much capacity?
 
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Maybe they lose 50% on that boat!

I leave my system off for a month and then turn it on for one night to drain and recharge the batteries.
 
Lifepo4 is not ideal for this task. While it's great for solar, home power systems, it does not shine in UPS applications. You are better off selecting a different chemistry for this purpose.

LIfepo4 is best stored at 30-50% SOC, and that's effectively what you're doing. You're storing it, ideally at 100% SOC, for however long it is between power outages.

Cyberpower is the shit tier of UPS's. I would recommend tripplite as 2nd to APC, which is top tier, but not by much other than price. I was using 6 tripplites for the decade before my off-grid switch.
APC hasn't been more reliable than Cyberpower since the early 2010's and now the buyer is paying a 50-100% premium just for the name. Schneider does make some good equipment, but that never filtered down to APC post-acquisition. Tripplite is for office depot power strips.

I don’t know about the rest of them but the EF delta2 fans run even when powering a 70w lightstrip. Stay away from them if you want silence.

Why not dyi? Depending on size requirements it shouldn’t be too difficult or expensive. Instead of solar panels just charge it from the grid.

You specify 1500w. How much capacity?
I would prefer an all-in-one just for the convenience and semi-portability. Secondarily, I would prefer to replace the batteries in my existing UPS with LiFePO4 units, because the UPS, with functional batteries, behaves exactly how I want it to. However, since the four SLA batteries it came with are most likely in a 2P2S configuration, that would mean getting compact, form-factor equivalent 12.8V lithium batteries that each have a 60A BMS. Were UPS's batteries a 4P configuration then 30a BMS would suffice, but it's not like I expect to find off the shelf batteries with either BMS.

DIY is an option as specified in my original post. But, what's an appropriate transfer switch? What is an appropriate rectifier / charger which can be paired with an inverter that when set up will SILENTLY pass through wall power unless and until there is a brown out or power failure? I am presuming this would be an inline topology rather than a double online, but I will put together either system so long as it makes no noise under regular grid-supplied power operating conditions.

Regarding capacity for an all-in-one, anything over a kilowatt hour is fine, 2KWh would be great. Were I to have a full spread out system then 12-48v batteries are exceptionally cheap these days and I'd get several kilowatts worth.
 
In the past 10 years i've had 3 cyberpowers fail in under 3 years and none last longer. I'm not talking about the batteries, im talking about the managemetn system. I've had APC's last 3-4 years. I've had Tripplite's last the longest at 5-7 years. These were all rack mount units in the 1500va variety.
 
I'm confused about battery storage. EG 4 says:

View attachment 286187
They are really storing the batteries. IE no longer charging them.

As a UPS it gets charged all of the time (to 100%) and that is what LiFePO4 is supposed to not handle well.

You might be able to size the battery such that you have it set to charge to 100% and then do not charge again until it gets down to say 50-60%.
 
Never mind. Since other than a helpful tip to avoid getting an EcoFlow Delta 2 there were no suggestions, I just bought four replacement 12v 9ah batteries and did a swap for less than 40% of what Cyberpower wanted for a new pack.

I guess this thread can be closed.
 
Lifepo4 is not ideal for this task. While it's great for solar, home power systems, it does not shine in UPS applications. You are better off selecting a different chemistry for this purpose.

LIfepo4 is best stored at 30-50% SOC, and that's effectively what you're doing. You're storing it, ideally at 100% SOC, for however long it is between power outages.

Cyberpower is the shit tier of UPS's. I would recommend tripplite as 2nd to APC, which is top tier, but not by much other than price. I was using 6 tripplites for the decade before my off-grid switch.
I hooked up a DIY built 12 volt LiFePO4 battery to my Tripplite APS 1250 battery backed up 120 vac. I think that was a good match, with battery set for AGM or Gel (would have to look at note to remember best choice). I have left some of my Tripplite back up set ups unattended for up to 9 month running lights and music, and could be security camera in neighbor hood where the grids goes off weekly or more. One flaw that is fixed with my LiFePO4 with my settings on a 200 amp capable JK BMS is: If Grid goes off long enough, your load can draw battery down to 10 volts before the Tripplite cuts off . That is a potential lead acid battery killer. That flaw is fixed when I connect my LiFePO4. Also .. I learned via Hans on experience, that the BMS I selected can block charge and/or discharge to the battery "separately" (not sure how). That means unattended, my BMS can disconnect my battery on discharge side while leaving the Charge route connected. While I need to test further, I believe that when grid comes back on (after battery is stop from discharging further), my battery will be charged back up to full Automatically.
 
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I have been a very long-time user of Cyberpower UPS units, but long wanted to switch to a lithium chemistry based system for the increased power density and run time.

The TLDR is that I want a solar generator that: 1) can output 1500+ watts; 2) has a reliable 10-20ms UPS-like transfer when the power goes out or the home voltage drops to around 115v; 3) is absolutely silent when in AC pass-through on wall power; 4) properly operate in a room with a noise ceiling of 25db with all noise making objects measured at a distance of under three inches (7.62 cm) from the objects; and 5) just to be clear not make any noise while acting as a still-plugged in UPS.

Back in the summer of 2022, I was looking for lithium battery info on youtube to have a small battery backup for the hurricane season that would last powering my kitchen fridge and possibly a one-room portable AC during a power failure until it was safe to fire up a portable gas generator. At the time, I was impressed by the Vigorpool Captain 1200 for being able to put the inverters in parallel so as to power any portable cooking appliance and readily fire up a medium-office scale laser printer... so I ordered a pair along with the parallel cable.

Although the Vigorpool units performed exactly as advertised, including having a great UPS transfer and load splitting when in parallel operation, I ended up being unable to replace my aging rackmount Cyberpower UPS because the Captain 1200s while in AC pass-through mode are not truly pass-through and the obscenely, obnoxiously loud fans frequently spin up even when the units are on standby with temperature readings of under 20C! Rather than real pass through like most old-fashioned lead acid based UPS companies, power trickles into and out of the Captain 1200's batteries while the inverter is on and that is almost constantly setting off their fans.

Because of that, I went back to using my rackmount Cyberpower system since it makes no noise unless and until the power goes out or voltage drops (because the county water company has pumps in the neighborhood that don't play nice with FPL's power lines). Unfortunately, and after "only" nine years of service, one of the batteries in the Cyberpower system has died.

I need truly quiet system while still receiving regular wall outlet 120v power. Making appropriate noise is fine when the power goes out, but in all other circumstance silence is vital.

Would like recommendations for any portable-ish all-in-one that fits my use requirements or alternatively battery / inverter / rectifier parts list that will also cover my silent UPS needs without being reliant on bluetooth or Wifi to work.
I built a UPS using an EG4 3000 off grid All In One on top of 15 kWh worth of LiFePO4. Search Battery Wagon w my Capt Bill handle, and you will find my Nov 2023 posts. I think most All In Ones can be configured for UPS ... (likely even lower tier ones, but do not have full picture,).
 
I saw a few fanless pure sine 300w inverters. Not sure if anything bigger is available for that silent solution that the OP is wanting.
 
Here is a Ampinvrt 1200 Watt pure sine wave Inverter w ac Charger that easily functions as a UPS. Say it has 3600 watt surge peak power. It currently costs $175 on Amazon. I got it delivered to a Costa Rica address for a total of $225 (w some $40 promo). I am limited in battery options here. To show a few neighbors an econ option for backup power, I purchased a Marine deep cycle lead acid w cca (dual use) for $210 from nearby auto tire store. That's an ok deal for this area. I give this econ option my thumbs up. I am letting my neighbors know they can use something like this for their wifi, computer office, music, tv, some lights, a fan, and even a security camera for 24/7 power.Thw Grid goes off and on weekly, if not daily around here. Sometimes, huge area are off for a half day. Of you look for this, these guy have allot of similar looking options that are only inverters. This unit also has an ac battery charger that charges at 15 amps (unless adjusted for less).

For Econ Solar option that could power wifi, computer office, low watt music tv center, and security cams 24/7, one can set this Ampinvt in battery priority mode, and put on a econ solar charge control connected to PV (I go for a 400 watt panel to get econ cost per watt) ... with Solar, I believe one could add a small refrigerator to the power strip load.
 

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I have been a very long-time user of Cyberpower UPS units, but long wanted to switch to a lithium chemistry based system for the increased power density and run time.

The TLDR is that I want a solar generator that: 1) can output 1500+ watts; 2) has a reliable 10-20ms UPS-like transfer when the power goes out or the home voltage drops to around 115v; 3) is absolutely silent when in AC pass-through on wall power; 4) properly operate in a room with a noise ceiling of 25db with all noise making objects measured at a distance of under three inches (7.62 cm) from the objects; and 5) just to be clear not make any noise while acting as a still-plugged in UPS.

Back in the summer of 2022, I was looking for lithium battery info on youtube to have a small battery backup for the hurricane season that would last powering my kitchen fridge and possibly a one-room portable AC during a power failure until it was safe to fire up a portable gas generator. At the time, I was impressed by the Vigorpool Captain 1200 for being able to put the inverters in parallel so as to power any portable cooking appliance and readily fire up a medium-office scale laser printer... so I ordered a pair along with the parallel cable.

Although the Vigorpool units performed exactly as advertised, including having a great UPS transfer and load splitting when in parallel operation, I ended up being unable to replace my aging rackmount Cyberpower UPS because the Captain 1200s while in AC pass-through mode are not truly pass-through and the obscenely, obnoxiously loud fans frequently spin up even when the units are on standby with temperature readings of under 20C! Rather than real pass through like most old-fashioned lead acid based UPS companies, power trickles into and out of the Captain 1200's batteries while the inverter is on and that is almost constantly setting off their fans.

Because of that, I went back to using my rackmount Cyberpower system since it makes no noise unless and until the power goes out or voltage drops (because the county water company has pumps in the neighborhood that don't play nice with FPL's power lines). Unfortunately, and after "only" nine years of service, one of the batteries in the Cyberpower system has died.

I need truly quiet system while still receiving regular wall outlet 120v power. Making appropriate noise is fine when the power goes out, but in all other circumstance silence is vital.

Would like recommendations for any portable-ish all-in-one that fits my use requirements or alternatively battery / inverter / rectifier parts list that will also cover my silent UPS needs without being reliant on bluetooth or Wifi to work.

I'm using an AFERIY Portable Power Station 3600W for this purpose. It's very quiet most of the time in UPS mode, with the fans coming on maybe for a minute every 20 mins or so just to keep things nice & cool inside. Interestingly, if you can cope with all the CCP "calls home" when you use the their app, you can set the max charge of the inverter when running in UPS mode so that it doesn't get charged up to 100%.

Now if someone can reverse engineer those calls home (I know the power station attempts to connect to their own MQTT server for example!), then you could write a nice little integration with Home Assistant & manage the power station entirely via your local network (& spoof the DNS entries so you end up talking to your own mqtt server instead ;) )

The switchover time is probably around ~10ms I reckon, and it's working well (got all my IT equipment running off it 24/7).

I'm using a Shelly Plus Plug at the wall socket to switch the Aferiy between UPS pass-thru mode & use-as-powerstation mode.

The Shelly plug has an MQTT connection to my Home Assistant, and I'm slowly configuring charging rules.

For fun, I'm also connecting one of the main outlets of the Aferiy to a Renogy inverter which in its UK incarnation, has an AC socket - which is also got a Shelly plug on it. The inverter will give me mains output on a 4kWh DIY crate battery that'll soon be up & running hopefully, for a modular & expandable secondary backup system if the grid goes down (we have a manual switchover to run the whole house in EPS mode for the existing 14.2 kWh battery <= wasn't so keen on an automated failover switch in case the main electric oven is on when it happens, which could cause issues as the inverter will only handle 3kW in EPS mode)
 
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