Feeling Solarwhelmed

[theavgs]

Im discovering there are deep deep mines to delve when it comes to just about every component related to power systems, and feeling a little overwhelmed with everything.

There is so much great discussion on all the details, the why's and the how to's. But I would love to hear from some of you, those that use solar as well as those relying on generators, what you have in your systems: a simple list of components, and how much your system cost to compile. Or, if you were doing it all over again from ground zero, what would your ideal setup be?

[brokedown]

The thing about solar power is you really need to have an idea of how much you expect to consume before you bother talking about it outloud.

[JDOnTheGo]

Everyone is different so there is no right/wrong answer. That said; I'd encourage you to think about your "mission." How and where do you want to live? What equipment do you plan to use? And so forth... once that is known, you can begin figuring out what is required to accomplish those goals.

Since the above various so widely, there is no common "equipment list." It's really a cookbook of ideas and possibilities that you assemble into a system that accomplishes what you require.

Not sure the above gives a clear idea so, for example... My mission was to live in the west (largely the southwest) with an entirely electric coach and rarely/never run a gas/diesel generator.

[PNW_Steve]

Like Brokedown said. You have to know the load that you will be supporting before you can design the system to support it.

Make a list of EVERY power consuming device that will be used in the bus, how much power it consumes and how much you use it.

Example: 42" LCD TV - 93 watts - 3 hours daily would consume 279 watt/hours (.279kwh) daily.

If a device is listed with current draw and not watts then take the current (amps) * voltage and that will give you watts.

Example: A device that draws 2.5 amps at 120 volts consumes 300 watts.

Once you have that done you can figure out how much solar and battery you need.

Also, I would strongly recommend going over to Forums - Solar Panels - Solar Panels Forum and read every one of the stickies in the off-grid, battery and RV sections. There is a ton of great solar info there. Some very knowledgeable folks over there.

[SandraBulocksRevenge]

Hey i see some of the great electrical masterminds of skoolie.net are on here so this seems as good a spot as any
I am working on wire sizing for my system. I have 2 100 watt solar panels wired parallel. I have a 45 amp morningstar tristar pwm CC. I have 2 12v 100amp AGM batteries. I have yet to purchase an inverter. The run from panel to CC is about 12 feet and I have sized at 8AWG. From CC to battery i have 10AWG cables for a 4 foot run. wiring the batteries in parallel i have 1/0 cable for a 2 foot run or less. The same wire is to be used for the future wiring of likely a 800w pure sine wave inverter which will also be about a 2 to 4 foot run. Do these wire sizes sound correct?
The next question is regarding fusing. going from my 2 100watt solar panels to a 45 amp controller, is there a need for a fuse being that the CCs rating is for so much larger an array? What are the parameters for sizing fuses from CC to batteries and then batteries to inverter? All basic utilities are to be wired into a 12vDC marine switchboard that comes pre breakered, should a fuse go between the batteries and that switchboard?
thanks

jack

[JDOnTheGo]

Originally Posted by SandraBulocksRevenge

Hey i see some of the great electrical masterminds of skoolie.net are on here so this seems as good a spot as any

Howdy Jack,

It's generally best to start your own thread for new questions. If nothing else, it helps to keep the conversation on track.

I'm assuming your panels produce something around 18VDC or less. If true, yes, all those wire sizes are appropriate. Some might argue over sized but that is far better than undersized and gives you some room for growth. Well done!!

Yes, a fuse/circuit breaker should be installed between the panels and CC as well as from CC to battery. Remember that these devices are in place to protect the wire. As such, locating them at the power source end of the wire is the goal. They are also very helpful (in this case) when doing maintenance and needing to open either/both of those circuits.

These Bussmann circuit breakers are good quality. Many different 'sizes' available.

[SandraBulocksRevenge]

[QUOTE=JDOnTheGo;289659]Howdy Jack,

locating them at the power source end of the wire is the goal.


In this case would one locate a breaker like you linked on the roof of the bus?

[JDOnTheGo]

Originally Posted by SandraBulocksRevenge

In this case would one locate a breaker like you linked on the roof of the bus?

That's the theory. However; it isn't always 'ideal'.

Think of a 20' long positive wire from a battery to an accessory (12VDC system). If the fuse is nearest the battery, a fault can occur anywhere along the wire and the entire wire will be 'powered down' when the fuse/CB opens. If the fuse is nearest the accessory and the fault occurs somewhere in the middle, you end up with a melted wire that is still hot.

I installed the CB for the solar array in the basement next to the charge controller. It is not ideal, I know...

[joeblack5]

Well JD is joking. " it is not ideal, I know"... But at the charge controller is where it should be. Solar panels are not able to generate more current then the Isc listed on the solar panel. The wire from the solar panel to the Charge controller has to be protected in case of charge controller failure where the battery will deliver current into to the solar panel. that current can be depending on condition be very high and is limited by the large circuit breaker / fuse between the battery and the charge controller. Usually that wire is much heavier then the wire going to the solar panel. The thinner wire can melt. hence the circuit breaker between the panel and the charge controller close to the charge controller.


Good luck Johan

[The Nebuchadnezzar]

I learned a lot reading this, you will too https://handybobsolar.wordpress.com/

[PNW_Steve]

Originally Posted by The Nebuchadnezzar

I learned a lot reading this, you will too https://handybobsolar.wordpress.com/

That is a great starting point.

Another great resource is: Forums - Solar Panels - Solar Panels Forum especially some of the sizing, battery and inverter stickies.