Staying with DC... or going AC during a system upgrade

couchsachraga · September 18

I've had a small solar setup at our off grid camp for about 15 years now. We started out with 6 panels from the 70's (yes, 1970s, still work just fine), and then upgraded when we wanted more power (from 180w out of 6 panels (total) to 1080w out of 4 panels). Lead acid batteries for 12 years (what I got out of the first set), moved over to lithium a few years ago. I just added another 2kw of panels, and meant to simply increase my battery bank (Midnite Classic 200 could handle the 2kw going in to my current 24v system), however as Kilovault is gone I can't get 2 more batteries... so I went for our next upgrade and have the new Midnite all in one system coming from our fine hosts and 15.3kw of batteries (I've added a shop so I've been contemplating having some more power where I don't need to fire up a generator anytime I need more than 300w AC we have from our current Suresine inverter). Right now only the on demand heater and one fan use AC (other than what I'll wire up for the shop). I"ll keep the water pump, chest refrigerator, and fans on DC, BUT I'm trying to decide if I'll swap all the lights and such to AC, or keep them DC and get all new LED bulbs (I could use another DC to DC converter, but at some point it make just sense to go AC with it all and make it "easier". The wiring was setup originally such that only the wiring on the "fuse panel" (current, would go to breakers for AC) needs to be changed.

So, has anyone else made this leap (or not), and why? I keep going back and forth, mainly as the inverter loses some efficiency, but then so does a converter, but with my larger battery bank and panels I'm not sure I need to be as paranoid about it as I've been in the past (with the all in one I'm keeping my original panels, so I'll be at 3.1kw vs the 2kw I'd planned). The one major draw we are contemplating is Starlink, which would likely be live all the time so we could monitor what is going on with the system. We use a cell hotspot and booster for that now and are on the edge of cell service (at times we have none, at others it is 30mb down / 8 up), and are limited to 15GB / month before overage charges.

Thank you for reading this rambling post, and any thoughts on why to either:
-Keep the usage as it is (convert to 24v for all but the new shop circuits)
-Convert to 24v where needed (pump and fridge), run 48v for lights (new bulbs), inverter only for new shop circuit (turn on when needed only if possible?)
-Run 24v only where necessary (pump and fridge), run new inverter all the time and swap it all to AC (add a breaker box, rewire to said box (time consuming but not a huge deal in theory).

706jim · September 18

I built my place in 1992 where there was limited inverter offerings. Trace 2512 and 800 watt units. I wired my place for 12 volts DC and also 120 volts AC.
If I were to do it again I would not bother with the DC wiring. Too much line loss and expensive appliances. In your case I would scrap the DC altogether and go exclusively AC. Your larger solar array will more than compensate for inverter losses. It sounds like you started out the same as I did (7 Arco salvaged panels for 24 volts and 170 watts) but now have something far more substantial.
Does your 24 volt fridge self defrost? I'm betting it doesn't and probably cost a ton of $.
My 120 volt fridge ($400) does this on a modest power budget.

NANOcontrol · September 18

There is no technical reason not to stay with 12V. I have a house which is wired for 12V. Refrigerator has an inverter which only operates when needed. Another inverter I turn on when needed for kitchen appliances. I have a dishwasher and large LG clothes washer that only operate when sun shines as it uses array voltage. Clothes washer uses hot water for all cycles and the clothes come out steaming. Domestic hot water is all from excess PV. Nobody thinks they have that much excess PV, but they do. My system is smaller than yours with only a car battery and a 50AH lithium purchased as a luxury. I don't feel like I'm wanting for anything except air conditioning, a total impossibility with all the shaded panels I have. Probably will end up buying an EV to get that. There are charging stations on almost every corner in our town. This was an extremely cheap system, but it does use a lot of technology to achieve it.

Your decision will be a totally personal choice based on what you are comfortable with. You have enough experience with the system to guide that choice.

couchsachraga · September 20

I have to say the point in the refrigerator really hit home. Yes, the Sun Danzer uses very little power, but for its size doesn't really hold much due to it being a chest refrigerator, and we've been using dehumidifying blocks in it forever and we still get plenty of ice forming. My wife votes it is worth just going to AC and replacing the fridge. This will be a big step up for us (1 kw of panels to 3 kw). I'm shocked how much cheaper panels are now than when I installed them at the camp, or on our primary residence. Thank you for your thoughts!

BB. · September 20

Regarding Starlink--This post is a couple years old, so new equipment will use less power (or more?):

https://forum.solar-electric.com/discussion/357292/starlink-satellite-system-power-questions?utm_source=community-search&utm_medium=organic-search&utm_term=starlink

Running a Starlink 24x7 could use a lot of energy (more in winter/icing conditions?)--as much (or possibly more) than running a full size home Energy Star type refrigerator/freezer...

The newer dishes probably use less energy--But need to measure yourself or find specs somewhere...

For example, quick search found this website:

https://starlinkinsider.com/starlink-power-consumption/

This site shows 68 Watts vs 169 Watts at "standard peformance" vs "high performance" data rates:

https://www.brooklyncampervans.com/post/starlink-for-rv-and-vanlife

A 68 Watt system running 24x7 would draw:

68 Watts * 24 hours = 1,632 WH per day

About the same power as an efficient home fridge.

The new(er) Starlink app does offer a sleep scheduling mode... 25 Watts (sleeping) vs 64 Watts or so running.

https://www.starlinkhardware.com/sleep-schedule-feature-added-to-starlink-app/

Using data consumes more energy, as does raining weather and interference with trees (example as unit tries to reconnect during poor reception).

-Bill

JRHill · September 20

We have only turned the heating unit on twice. Once to test the function and then one time last year when the sleet was really heavy and then it was only 30 min. 1st time in 3 years. Of note the antenna makes some heat even in normal mode. We're in the rain shadow of the Cascades. It can freeze up hard.

Normal power draw at ~70 watts? Yup. I thinks its a bit less that Hughes and about the same as DishNet. That's about the only comparison I could make. Oh, that's right, they're all satellite stuff.

Teasing y'all in my tone but I hope I made my point of Starlink vs the options.

couchsachraga · September 26

Thank you both for your thoughts! I've looked in to bringing fiber in there, but looks like 50k+ for that, which pretty much rules it out. I've done some research on the different versions and it seems that the newer ones are better... sort of.... So we'll see. I can certainly shut it down, but then lose all my monitoring. Not the end of the world, but it IS nice to know what is going on up there as well as turn the heat on remotely for when we head up (usually once every week or two, but not always). It will be much easier in a few years when we hope to be up there full time (with a much larger solar setup with backup generator tied in).

Staying with DC... or going AC during a system upgrade

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