Building My First DIY Solar Generator

[wclubin]

Am I correct in thinking that to build a portable solar generator all I need to get are the following if all I will be running on it are 110V 60Hz household appliances:

1. Solar Panels
2. Charge Controller
3. Battery
4. Inverter

I know I might want a box to put it in and I will need wires and maybe some solder etc. to put it all together, but other than those little things, the above four components are all I need to build a solar generator? Also, I watched some videos where they were putting fuses in the circuit in places; anyone know if that is required and where to put them? Thanks for your help.

 

[12VoltInstalls]

watched some videos where they were putting fuses in the circuit in places; anyone know if that is required and where to put them?

Fuses are required:

• At the battery in line with the inverter feed cables
• At the battery for any DC connection
• At the panel(s) if sum Amps is within 80% or more of the panel max fuse rating with the assumption that the PV wires exceed the sum current by 20%

Hopefully that’s worded well. Was trying to be succinct.

 

[wclubin]

Well, since this is a beginners discussion I guess I am allowed to say I don't fully understand? So here are my questions:

You said "At the battery in line with the inverter feed cables." From what I understand, the positive battery terminal connects to the positive inverter terminal. And the negative battery terminal connects to the negative inverter terminal, right? You are saying to put the fuse along the line that connects the positive terminals?

You said "At the battery for any DC connection." But I am only connecting household appliances that run on the 110V 60Hz, so that means I will not have any DC connections, right? So I don't need to worry about this?

You said : "At the panel(s) if sum Amps is within 80% or more of the panel max fuse rating with the assumption that the PV wires exceed the sum current by 20%." From what I understand, the solar panel has a positive and negative terminal. So what you are saying is that only if certain conditions are met should I include a fuse, and that the fuse goes in the line that connects the positive panel terminal to the positive controller terminal? And what I think you are saying is that solar panels come with a built in fuse, and if the amps that the panels will be passing out of them is 80% of their fuse rating then an additional fuse should be placed on the wire coming from its positive terminal? And I have no idea what PV wires are and what you are saying about them.

Thanks for the help

 

[12VoltInstalls]

You are saying to put the fuse along the line that connects the positive terminals?

Yes

So what you are saying is that only if certain conditions are met should I include a fuse, and that the fuse goes in the line that connects the positive panel terminal to the positive controller terminal?

yes
But not “only if certain conditions” but it is only required if the sum current exceeds the fuse rating of the panel or the wire (which is possible but not likely in a smaller system). (This info will be or should be on the panel label)
Fuses are a good idea in practice.

what I think you are saying is that solar panels come with a built in fuse, and if the amps that the panels will be passing out of them is 80% of their fuse rating then an additional fuse should be placed on the wire coming from its positive terminal?

No built in fuse. The max fuse rating can be thought of as the tolerance of the panel in a short circuit event; how much current it can withstand before meltdown if you will. It should be planned around not planned for.

have no idea what PV wires are and what you are saying about them.

PV wires/cables are the panels to SCC cables. Usually they are supplied as 10ga (30A) with MC4 connectors or sometimes 8ga (I make them 8ga but it’s usually overkill in small systems)
You don’t want more amps in the PV cables than their ratings. While in a properly designed system the panels are usually the limitation not the cables, in a powerful ‘small’ system if you have a number of panels in parallel it is possible to exceed 30A input.

You should look up the video that Will did that covers basics of electricity with small solar. That will give you context for understanding rather than A/B answers that I’m providing here which are answers but are merely facts to memorize and not contextual subsets of understanding. Context is the power that will make the thought balloon lightbulbs come on for yourself.

 

[DThames]

Fuses are required:

• At the battery in line with the inverter feed cables
• At the battery for any DC connection
• At the panel(s) if sum Amps is within 80% or more of the panel max fuse rating with the assumption that the PV wires exceed the sum current by 20%

Hopefully that’s worded well. Was trying to be succinct.

Just to be clear to the original poster, there is not a need to fuse a single string of panels.

 

[DThames]

Am I correct in thinking that to build a portable solar generator all I need to get are the following if all I will be running on it are 110V 60Hz household appliances:

1. Solar Panels
2. Charge Controller
3. Battery
4. Inverter

I know I might want a box to put it in and I will need wires and maybe some solder etc. to put it all together, but other than those little things, the above four components are all I need to build a solar generator? Also, I watched some videos where they were putting fuses in the circuit in places; anyone know if that is required and where to put them? Thanks for your help.

Watch these videos, part one, part two.

 

[ianganderton]

As far as components goes I would add a shunt based battery monitor to keep any eye on state of charge and power use

 

[DThames]

As far as components goes I would add a shunt based battery monitor to keep any eye on state of charge and power use

I built a power box recently. I included a Bluetooth BMS from Overkill Solar and a shunt type monitor. Other than the need to have a phone to look at the battery state, they have largely redundant functions. Both will show state of charge, amps in, amps out, etc. If I were doing it again, I think I would not put the shunt monitor in the build.