Need some help for my solar system in my campervan

[baarte]

Hi everyone,

I'm planning on building a pretty simple and cheap solar system in my campervan located in Australia. I have a rough idea of what I need but I'm not sure about the linking components. Such as fuses and wires.

We are going to use it for powering:
- A fridge
- 2 iPhones
- 1 Macbook (is the inverter size of 600w enough?)
- Maybe a regular fan

I've attached my draw so you guys can get an idea of what I think it's going to look like. I've had a hard time calculating the usage and currents of the appliances and want to know if what I've come with works and most importantly is it safe. Also what do I need to ground to my van's chassis and what size wire I need to use for it?

As you can see in the draw I didn't come up with the wire and fuse sizes for the small appliances such as the fridge. I hope someone can help me determine what my fridge (https://www.amazon.com.au/gp/product/B082WPJ6RC/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1) needs and what the other 2 ports need for wire and fuse.

These are the items I have in mind:
- Battery ---> https://www.harveynorman.com.au/giantz-120ah-deep-cycle-battery-power-12v.html
- Inverter ---> https://outbax.com.au/600w-pure-sine-wave-12v-to-240v-inverter
- Solar panel ---> https://outbax.com.au/maxray-120w-1...-boat-caravan-camping-power-mono-charging-kit
- Charge Controller ---> https://outbax.com.au/maxray-20a-12v-24v-solar-panel-battery-regulator-charge-controller-with-usb
- Fusebox ---> https://www.amazon.com.au/ESUPPORT-...keywords=6+way+fusebox&qid=1582253117&sr=8-11

If you have any comments or tips, feel free to give them!

Cheers,

Maarten

 

[Dzl]

Your battery gives you (120/2) x 12 = 720 watt hours (Wh) of usable capacity.

• Your laptop likely needs less than 75Wh per charge
• Your phones likely need about 15Wh each per charge
• The fridge will be your biggest consumer, the add states 200Wh, to be safe I would budget at least twice that
• Not sure what you mean by regular fan, it'll be most efficient if its a 12v fan. To calculate the watt hours it will consume, find the wattage (or the amperage x voltage if that's all you can find) and multiply by the number of hours you think you would use it in a day.

Sounds like your battery should have the capacity for what you need (especially considering that your phones and laptop have their own batteries so if you can charge them off the panels that's extra capacity.

But your solar panel might be a bit small for the rest of your system. Assuming an overall efficiency of 70% and 5 hours of sun, your looking at being able to feed 420 Wh into your battery bank. This may well cut it, if your fridge is as efficient as it claims, but if it were me I would probably bump my solar up to 200w, especially considering that the flexible panels are not known for their efficiency or heat dissipation abilities. As for the inverter, 600w should be fine for a laptop (your charger is probably 30-60 watts), you could also get a DC laptop charger that plugs into a cigarette lighter socket.

 

[baarte]

Your battery gives you (120/2) x 12 = 720 watt hours (Wh) of usable capacity.

• Your laptop likely needs less than 75Wh per charge
• Your phones likely need about 15Wh each per charge
• The fridge will be your biggest consumer, the add states 200Wh, to be safe I would budget at least twice that
• Not sure what you mean by regular fan, it'll be most efficient if its a 12v fan. To calculate the watt hours it will consume, find the wattage (or the amperage x voltage if that's all you can find) and multiply by the number of hours you think you would use it in a day.

Sounds like your battery should have the capacity for what you need (especially considering that your phones and laptop have their own batteries so if you can charge them off the panels that's extra capacity.

But your solar panel might be a bit small for the rest of your system. Assuming an overall efficiency of 70% and 5 hours of sun, your looking at being able to feed 420 Wh into your battery bank. This may well cut it, if your fridge is as efficient as it claims, but if it were me I would probably bump my solar up to 200w, especially considering that the flexible panels are not known for their efficiency or heat dissipation abilities. As for the inverter, 600w should be fine for a laptop (your charger is probably 30-60 watts), you could also get a DC laptop charger that plugs into a cigarette lighter socket.

Thanks mate! I already had some doubts so I'll probably upgrade my solar to 200w. Do I need to put a fuse between my panel and charge controller? What size do you reckon, 20A? And 20 between my charge controller and battery?

Also, I need to ground my inverter but do I also need to ground my battery and/or controller/panels?

Cheers!

 

[Dzl]

Do I need to put a fuse between my panel and charge controller? What size do you reckon, 20A? And 20 between my charge controller and battery?

This is a somewhat unsettled question. There is a post on the topic here. There is some question as to whether a fuse between Panels and SCC is useful on smaller systems, this article explains it pretty simply. Amy from the AltE store recommends using a breaker roughly 150% of the amperage from your solar array (obviously size your wires >150%). A circuit breaker makes much more sense than a fuse in this location as you can use the breaker to disconnect the panels to cut power.

Also, I need to ground my inverter but do I also need to ground my battery and/or controller/panels?

Someone more knowledgeable than me should answer this for you. I don't entirely understand how grounding applies to DC circuits, especially on a vehicle.

edit: also @FilterGuy started this great thread on fusing here, its worth a read

 

[Kcp]

Just to butt in a sec and leave- the fridge is DC, figure it'll always draw just under an amp and 4-4.5a when the compressor is on- I have an Alpicool C20. For inverter size look at the power brick of the macbook (if it has one- don't know Apple stuff) to know how many watts it uses, but guessing 600w is fine.

 

[Dzl]

For inverter size look at the power brick of the macbook (if it has one- don't know Apple stuff) to know how many watts it uses, but guessing 600w is fine.

Most modern non-gaming laptops use <65w charge rates of 30-65 watts are the norm. There are also a decent amount of 12v cigarette lighter laptop chargers on amazon which wouldn't require an inverter.

 

[Kcp]

Most modern non-gaming laptops use <65w charge rates of 30-65 watts are the norm. There are also a decent amount of 12v cigarette lighter laptop chargers on amazon which wouldn't require an inverter.

Nhh, 12-19v requires power from the adapter also so which is less? adapter or inverter? Have an Asus gaming laptop requires 19.5v input and a Acer NAV50 netbook just at 19V, the powerbrick sizes are for the amps not the volts- I'd take a pure sine inverter over adapter any day simply due to it's versatility.

 

[Dzl]

Nhh, 12-19v requires power from the adapter also so which is less? adapter or inverter? Have an Asus gaming laptop requires 19.5v input and a Acer NAV50 netbook just at 19V, the powerbrick sizes are for the amps not the volts- I'd take a pure sine inverter over adapter any day simply due to it's versatility.

Not sure if I'm understanding you correctly, but its not an either or situation, all other things being equal, it will always be more efficient to cut out the inverter.

Your laptop needs 19-20V DC one way or the other. So if you go the inverter route you are going 12V DC --> 110V AC --> 19V DC and if you go the DC charger route you just have to convert from 12V DC --> 19V DC, this is inherently more efficient because (1) you aren't converting twice, and (2) inverters generally speaking significantly less efficient than DC-DC buck-boost converters.

So you don't really get to:

take a pure sine inverter over an adapter any day

Its either Adapter and the Inverter or just a single dc-dc adapter

 

[kenkoh]

Do I need to put a fuse between my panel and charge controller?

I asked WP same question and he said 1 string no need for a fuse but after tons of questions here I've decided to put a switch for easy disconnecting. I'm a novice. My 2c to help because others helped me, I made this chart for myself maybe you can use it. Good luck.

 

[Kcp]

Not sure if I'm understanding you correctly, but its not an either or situation, all other things being equal, it will always be more efficient to cut out the inverter.

Your laptop needs 19-20V DC one way or the other. So if you go the inverter route you are going 12V DC --> 110V AC --> 19V DC and if you go the DC charger route you just have to convert from 12V DC --> 19V DC, this is inherently more efficient because (1) you aren't converting twice, and (2) inverters generally speaking significantly less efficient than DC-DC buck-boost converters.

So you don't really get to:

Its either Adapter and the Inverter or just a single dc-dc adapter

Let me simplify: My 1000w pure sign inverter uses .9 amps to power itself, 1.5a when the fan turns on. I can run a corded Dremel with it, my entire entertainment station AND charge my laptop and phone and it's not wired to the ac panel. Adapters are great for day trips, have one in my car.

 

[Dzl]

Let me simplify: My 1000w pure sign inverter uses .9 amps to power itself, 1.5a when the fan turns on. I can run a corded Dremel with it, my entire entertainment station AND charge my laptop and phone and it's not wired to the ac panel. Adapters are great for day trips, have one in my car.

I get what you are saying (and I agree with you on the versatility and usefulness of a pure sine inverter), but I want to reiterate, its not an either or thing. You can (and most do) have an inverter, it still makes sense (from an efficiency and power savings standpoint) to power as much as you can directly from DC.

As you said, your inverter draws 0.9 amps, that's a little over 275 watt-hours a day, if its always on, then you have to consider that premium inverters have maximum conversion efficiencies in the low 90's, and most inverters hover around the mid 80's. That's a substantial amount of wasted power for a small system.

Inverters are a great and useful component to have and the easiest option in many cases, but where efficiency is important, its ideal if they can be switched on only when needed or left in a sleep/eco mode if they have one.

 

[El Jack]

I’m with @Dzl. Running an inverter to charge a DC device is inefficient.

You can it’s just not the best way.