Not sure what system to build

[cmporter83]

Hello! Excited to find this place. I’m currently wanting to dabble in this world and want to start with a “small” system. Basically I want to see if I can power a home security camera system purely on solar. The system is 8 PoE Cams and an NVR that records everything and works as the PoE switch. When I asked the vendor what sort of power the NVR uses they said 48V / 2A. That seems like a lot but tell me I’m wrong. With the basic math I have learned it seems that’s 96 Watts, so running 24/7 I need a system that can provide 2400 Watt Hours, right? That’s a big system, at least from what I can tell. I need help. Ha!

 

[Rednecktek]

Yup, constant loads add up fast, especially when you try to last through multiple days of lousy weather.

2400wh a day is about right, and that's assuming you get enough sun to fully charge every day. Rule of thumb is 3 days so a 150ah 48v battery would be your target.

It's not undoable but it's going to cost a bit.

 

[E. Cho]

Yes and no.

The NVR has a low spec draw "without a hard drive", a bit higher with but that is only when it is reading or writing data. Next each PoE camera will have a minimum draw of about 7-12+ watts at 120V, depending on camera, maybe bitrate, data transfer, motion detection frequency, if IR LEDs are on or off all night, if a spot light is on or off and so on. Meaning, things on my setup turn off and on through the day and night and there are lots of recording and motion detection variables.

A Watt meter is really the best way to monitor an average use. So it could be as you guesstimate or IME lower. But I don't keep IR lights on all the time as insects like moths or bats can set off many false alarms, despite many motion setting tweaks.

 

[cmporter83]

Ouch. Was hoping for better news. Ha!

A $1,000+ battery, 6 100W panels, inverter etc. to power a $400 security system.

Is there a better way to build that system with multiple smaller batteries? With an inverter, do the batteries have to match the appliance voltage?

Thanks so much for all your help!

 

[SamDeleted]

A $1,000+ battery, 6 100W panels, inverter etc. to power a $400 security system.

Is there a better way to build that system with multiple smaller batteries? With an inverter, do the batteries have to match the appliance voltage?

Yes with lead acid , you can series
/parallel to make pretty much whatever voltage you like.

But It's more complicated with lithium, these smaller 12v batteries with built in BMS aren't necessarily designed to be put in series at all, some will only accept 24v max


You have to research about whether any specific lithium is suitable to be wired in series

 

[hwy17]

You won't know what it really draws until you can put it on a "kill a watt" or another watt hour meter.

The cameras probably do not draw 96 watts all the time.

 

[SamDeleted]

I need a system that can provide 2400 Watt Hours, right? That’s a big system, at least from what I can tell. I need help. Ha!

It's not a big system, it's a medium-sized set up

But it'll still cost ya!



My 2.5kw almost flat mounted solar array could handle that no problems at all . A few hundred pounds worth of second hand AGM batteries and a cheap 5.5kw hybrid inverter, I have 20kwh of battery , you won't need half that much for what you're doing here


For example:

10khw of battery , a 3kw hybrid inverter, and 3kw of panel

Would cost roughly:

£450 on batteries 10kw used AGM
£720 on solar panels 3kw ex-solarfarm panels
£300 3kw hybrid inverter
£50 in cable and fuses

£1,500~. And that's done on the cheap

 

[Rednecktek]

You won't know what it really draws until you can put it on a "kill a watt" or another watt hour meter.

The cameras probably do not draw 96 watts all the time.

This. Planning for worst case scenario max load all the time is good for getting on paper, but without accurate info it could very easily be over built for your needs. There are a few places you can cut costs significantly though, namely:

Find used panels from someone's old roof install that got upgraded. Around here the average is a 250-ish watt panel for about $100 give or take.
Don't get the high-end-name-brand-Victron-sell-your-kidney parts. Any SCC that turns solar DC into battery DC will do the job and it is often times cheaper to get a Tier-2 or a couple of Tier-3's and spares for less than what a Blue box costs.

WallyWorld DC29 deep cycle lead acid batteries are good for about 720Watt hours (60Ah usable), can be paralleled and serialed all day long, and only cost about $100ea out the door. That's a 2880Wh (48v @ 60Ah) usable battery bank for about $400. 2 days worth would be about $800.

Hammer crimpers are a lot cheaper than hydraulic crimpers and still get the job done.

I don't se a need to get an inverter involved if it'll run on 48v directly so that saves a lot of money.

On average DIY'ing a battery saves about 30% over a pre-built.