Hi everyone,
Since I need to replace the main UPS of my homelab, this crazy idea keeps bouncing around in my head.
Instead of the usual Eaton or APC units, to create a more self-sufficient setup, I’m considering using a solar power station as both a UPS + primary power source.
I’d like to use something like a Delta 3 or a Bluetti.
So, in summer, I should have enough power to both run the system and charge the battery during the day, and use the battery through the night.
Then, when the battery is low and there’s not enough sun, the power would come from the main household supply.
I’ve seen that many power stations provide a pure sine wave and response times under 20ms (which is better than my old APC).
What do you think about this?
The average power consumption of the entire system is about 200W (router, switch, PoE cameras, NAS, and a couple of mini PCs running Proxmox) with max 300W at boot.
I am thinking about something like this:
+----------------------+ +--------------------------+
| Solar Panels | | Main Power Grid |
| (DC input) | | (AC input) |
+----------------------+ +--------------------------+
\ /
\ /
\ /
\ /
v v
+--------------------------------+
| Power Station |
| - Input: DC (solar) |
| + AC (grid) |
| - Internal Battery |
| - Pure Sine Wave AC Output |
+--------------------------------+
|
v
+-------------------------------+
| AC Distribution Box |
| (Circuit Breakers Panel) |
+-------------------------------+
|
v
+-------------------------------+
| Homelab / Server |
| (router, switch, NAS, POE, |
| Proxmox, mini PCs, etc.) |
+-------------------------------+
At 200W power consumption I’m not sure how long the battery in this system will last but I’m guessing a couple minutes. The idea is good to lower your electricity bill, but likely not as a permanent replacement for backup power. What do you do if there’s a mains power outage at night?
If you’d like a truly resilient power system you should consider a backup generator in addition to the solar.
This power stations works in Wh not Vh, so if a 1000VA UPS can give 5-15 minutes a 1000 Wh can give 1 hour
If my math is correct 1000Vh are near 100 Wh or 0.1 kWh
I am not very expert in this so I might be wrong..
I am considering the Delta 3 plus, it has a switch time less than 10ms (so very good), 24/7 and an internal battery of 1 kWh.
Here is the link:
So, with the unit alone, adding a threshold to preserve the battery (min. 20% max 80%) I should have near 3 hours.
If I add a 2 kWh battery I should theoretically increase the battery hours to 9. Not bad.
Also during the day (especially in summer) I can power the homelab while charging the battery (2x400W panels)
There is a bit of mixup here between VA and Wh. Vh doesn’t exist and was probably a typo.
A UPS rated at 1500 VA means it can theoretically provide up to 1500 Volt-Amps. However, this isn’t equal to Watts unless the power factor is 1. Most consumer UPSes have a power factor around 0.6–0.7. So 1500 VA × 0.65 PF = ~975 W usable power.
The DELTA 3 unit you linked has indeed an uptime of about 3 hours at 200W consumption. And if you install the supplemental battery you will likely get 8+ hours of uptime with 0 solar.
While charging the batteries on the solar alone, most panels average around 70–80% of rated capacity over the usable sun hours which assuming it’s during summer in a decent region with good clear skies gives us Effective solar output ≈ 550–650 W during peak sunlight hours. Taking into account your 200W consumption, your batteries will charge at 400W during these peak hours.
It’s a bit rough to know exactly your solar output over a full day, and over a full year, but assuming some averages here a let’s use a daily average is 4–5 hours of peak sunlight for many regions (Europe/US) during summer. Plugging those numbers in we get:
600W × 4.5h = 2.7kWh/day
Let’s add roughly 6 more hrs of shoulder sun at say 150W energy:
150W × 6h = 0.9 kWh/day
So in total, on a good summer day with clear skies you might get up to 3.6 kWh from your solar panels.
However your total power lab consumption over the 24 hr period is
200W × 24h = 4.8 kWh
Your solars alone won’t be able to fully sustain your home lab consumption, but you’ll have significant energy cost savings.
ymmv but if you have the space and having 100% power uptime is important to you, I’d skip the extra battery and add a generator, typical consumer models can easily provide 2000W+ for 24hr on fossil fuel and get the peace of mind that a power outage in less than ideal timing and conditions won’t lead to a home lab blackout
FWIW, I have a massive 7.5KVA APC UPS that powers all my machines. At a draw of 400W it will last 175 minutes, Potentially that’s not enough time so I have 2 x APC 1500VA units downstream of the big UPS & everything vital hangs off them (some stuff like monitors doesn’t get this “extra” UPS protection).
I have survived a power cut of just under 270 minutes but I was thinking I’d lose everything just before power returned to save the day!
it was an idea I considered but I have to - read “remember” - to refuel it, and also it makes noise when in run.
The idea was to place everything on the basement near the homelab, so nothing outside but the panels that will been placed on the wall most exposed to the sun (more easy to install - like the panels for balcony) or directly on the roof.
I just need to check if I can plug every solar panel (lg or so) or do I have to use their foldable and - to me - not very durable panels
I live in an apartment, no option to install solar panels or have a generator but have dreamed about one day owning a house and that’s the setup I’d get solars + generator and a small UPS, however that would be for the entire house or as much of it as possible not just the home lab.
But I do have a pretty well sized UPS array that can power the entire home lab for little under 3 hours. Luckily we seldom have power outages around here and longest one so far was roughly 2 hours.
Having the home lab up at all costs isn’t critical to me. There’s a NUT monitoring system in place that automatically shuts down everything if juice in the UPS array goes below 20%.
I’d recommend getting 4x400w panels. This will give you some headroom in winter or on cloudy days. 400W panels will produce 400W only in ideal conditions.
I use an Ecoflow Delta 2 in my home lab set up, without the solar panels, just AC mains behind it. It does not switch fast enough to be a primary UPS, I tried it. I ended up using a small UPS I had laying around. My setup goes AC mains—> Ecoflow—>UPS—> PDU.
Also these power stations are not quiet. The fans run anytime any device is drawing power, regardless if the power is coming from the AC mains or the battery. They do not drop the inverter out of the circuit, ever. Its not like a true UPS. For example, if you plug in your 200 watt load, and you are drawing power from the AC mains, the circuitry doesn’t bypass the output inverter and power doesn’t go from the mains straight to the outputs. That inverter always runs, and all of the output comes from the inverter. You can avoid this by adding an automatic transfer switch in front of the power station.
In short, its not an ideal solution. I have tried it. That being said, I paid $500 for it (so it was relatively cheap) and it will run my entire home lab for 4-5 hours in a blackout. I think you would be better off getting something designed for residential installation, and not something designed to be portable.
- to refuel it, and also it makes noise when in run.