Why Solar?
What, me? Solar?
I didn't go solar to save the planet or to prove a point. I went solar because there was no power on site. I needed to charge batteries, use tools, and have light before the power company could run a line out to me. That meant gas powered generators or solar. Generators are too loud and smelly, so solar it is!
Not only that, but I'm cheap too, and the power company wanted to charge me quite a bit more to get power to the warehouse than it would cost to get started with solar.
Of course, now that I've started working with solar, I've decided I like the energy independence, and am quite pleased with how much fun it is to learn about and build out solar solutions.
The First Solar
Equipment List
To get solar to work, you'll need a few things that all play nicely together.
- Solar panels to collect the energy
- Battery(s) to store the energy
- Charge controller to make sure your panels don't fry your battery
- Power inverter so you can use the power you collected and stored
Simple, right? Well, mostly.
The Easy Way
Buy a solar generator like the one from Nature's Generator (See first picture). That's what I did to get started. It comes with everything you need, including solar panel and all the cables. Note, you'll pay quite a premium for getting the turnkey system, but it's easy and it proves that solar works.
Or You Can Do It Yourself!
Cheaper and infinitly more fun is to build out your solar farm from parts. But you gotta know some basics first.
Solar Panels
Your solar panels come in Watts, typically 100W. But they only produce 100W on a perfect day; most days it's much less. Your batteries store Amp-hours of power. How big a battery or batteries do you need to get will depend on how many amps you need to pull for how long.
How do you determine this? You figure out how many Watts the appliances you want to use will draw, and you do the math to determine amp-hours needed.
Except your appliance runs on electricity at 110 volts, and your batteries store electricity at 12 volts. So you need to convert.
Then, once you've determined your battery capacity, you'll need to make sure you can charge those batteries without damaging them. That's where the charge controller comes in. Details on that later.
Now you need to convert from 12 Volt power to the 110 Volt power your appliances can use, so you get a power inverter. Inverters come rated in Watts. Good! At least you've seen this measurement before.
How Many Watts?
Your cell phone charger will draw about 10 watts, and your TV about 200 watts. Your air conditioner will draw 1500. But each will draw roughly twice that to start up. Your air conditioner may take up to 5000 Watts to get started before it goes back to drawing 1500 Watts.
Next: Putting the components together
Assemble your own Solar Generator
Gather Components
Connect the first battery to the Charge Controller
Connect the first battery to the Charge Controller
I've got two 75 amp -hour deep cycle batteries, two 100W solar panels, a MPPT charge controller, 5000W power inverter, fuses and cables.
Connect the first battery to the Charge Controller
Connect the first battery to the Charge Controller
Connect the first battery to the Charge Controller
The charge controller needs power to do it's thing (automatically recognizing 12/24/36/48 volt systems), so attach the battery first.
Connect a Solar Panel
Connect the first battery to the Charge Controller
Hook up the Power Inverter
Next, connect a Photovoltaic panel (PV panel) to the charge controller. Make sure the charge controller indicates a charging state instead of an error.
Hook up the Power Inverter
Turn it on, see if it works!
Hook up the Power Inverter
Since most of my stuff runs on 110 volt power, I'll need to use this inverter to convert from 12v to 110v.
Turn it on, see if it works!
Turn it on, see if it works!
Turn it on, see if it works!
Yay! It turned on!
Plug Something In
Turn it on, see if it works!
Turn it on, see if it works!
Yes! We have light!
And there you have it. That's the most basic system. Panel -> charge controller -> battery -> inverter -> appliance.
Expanding Capacity
Adding a Battery in Parallel
Note to Self: Standardize on one panel type.
Add Another Solar Panel in Parallel
Connecting batteries in parallel (positive to positive, negative to negative) adds amp-hours. With two 75Ah 12v batteries, I have 150 Ah at 12v..
The next project will be connecting the batteries in series to get more voltage.
Add Another Solar Panel in Parallel
Note to Self: Standardize on one panel type.
Add Another Solar Panel in Parallel
By using 2-to-1 connectors, I can add another panel in Parallel, increasing the amperage output to the charge controller.
Note to Self: Standardize on one panel type.
Note to Self: Standardize on one panel type.
Note to Self: Standardize on one panel type.
It's best to pick one brand and model of panel and stick to that so you can connect panels in parallel or in series. It's not the best plan to connect diferent kinds of panels to the same charge controller.
Beyond the Basics
More Watts of Demand = More Amps from a 12v System
As my demand for more hours of more watts increases, I found I need to expand my solar setup. Watts = Volts x Amps, so the more Watts I need to consume, the more amps my 12 volt system needs to push out.
More Amps = More Heat and Power Loss
That's problematic, because more amps puts a lot of heat and stress on my wiring. It wastes more energy, and increases fire hazards. Not a good solution around temperature sensitive batteries and equipment.
More Volts = More Watts with Fewer Amps
So to keep amperage requirements reasonable, I'll need to increase system voltage. Fortunately, that's not too hard. Wiring batteries in series instead of in parallel will increase the voltage. So two 75 amp hour 12 volt batteries in series results in 75 amp hours at 24 volts. Four 12v batteries in series is 48 volts. Match that with a 48 volt compatible charge controller and inverter and you're good. Almost.
Solar Panel Requirements
There is the "water won't flow uphill" problem with electricity. In order to get energy to flow into a 48v battery array, you need a source greater than 48 volts. The 15 - 20 volts coming from the 100 watt solar panels is fine for a 12 volt system, but it won't budge the charge on a 48 volt system.
To get that done, I'll need to connect the solar panels in Series. Not a problem in and of itself, but I will want more amps coming into the system to charge the batteries all the way during short daylight winter days. I'll solve this by having six panels. I'll make two sets of three connected in series, and then I'll connect the two sets in parallel and run that to the charge controller.
Battery Requirements
I'll do the same with my battery array. It will take four 75ah batteries to get to 75ah at 48v. By my calculations, my compressor, pressure washer, and air conditioner will demand 4500 watts from my 5K Watt inverter at peak usage. At 48 volts, 4500 watts will suck up about 94 amps (figure 100 amps to include motor startup costs). This means my 75 ah array gives me about 45 minutes of power at that level. If I had 150 ah, I could get 90 minutes of having everything on.
Support Sustained Usage
Realistically, I'll probably want to sustain 3000 watts, which is the air conditioner, lights, a mini fridge, portable battery chargers, and occasional power tool use; about 65 amps per hour at 48v.
Now, when planning battery capacity, having a 75ah array does not give you 75 actual amp hours. With lead-acid batteries, even deep discharge batteries, you're really only supposed to discharge to 50% of total capacity to get maximum lifetime out of your batteries. So we'll need to take that into consideration.
An array of 150ah is a good start, but ultimately, I'll want to connect three groups of 48v 75ah batteries to get 225 amp hours @ 48 volts, or ~115 usable amp hours. 3000 Watts divided by 48 Volts is 62.5 Amps, so 115 usable amp hours gives me 115/62.5 or just under 2 hours of 3000 watts continuous usage, not including any solar replenishment taking place during the day. I'll probably be running 8 panels by the time I get to three sets of batteries in parallel. Good thing panels are less than $100.
48 volt expansion project
The Battery Bench
Solar Panel array in Series
4x12v = 48v Battery Array
Step one in the 48 volt expansion project is the battery bench. I'll need a stout bench to hold 8 48ah batteries! That's the inverter and the charge controller on the left.
4x12v = 48v Battery Array
Solar Panel array in Series
4x12v = 48v Battery Array
Connecting 4 12v batteries in series combines voltage (parallel combines amp hours). You can see I've connected the positive terminal from the first battery to the negative terminal on the second battery. On the last battery, the positive terminal is connected to the inverter through a fuse. The negaitve terminal from the first battery goes diretly to the inverter to complete the circuit.
Solar Panel array in Series
Solar Panel array in Series
The 48v Array, Inverter and Charge Controller
The bottom half of this array is still hooked up in parallel, but the top four panels are connected in series to be certain they generate more than the 48 volts required to charge the battery array.
The 48v Array, Inverter and Charge Controller
The 48v Array, Inverter and Charge Controller
The 48v Array, Inverter and Charge Controller
Everything is hooked up now. Panels to charge controller to fuse to battery array. Battery array to fuse to inverter. Inverter to whatever needs power.
Solar Array in Series and Parallel
The 48v Array, Inverter and Charge Controller
Solar Array in Series and Parallel
I now have three parallel sets of two panels in series charging my 48v setup, and three panels in parallel powering my original Natures Miracle setup.
4x12v x 3 Parallel Battery Array
The 48v Array, Inverter and Charge Controller
Solar Array in Series and Parallel
I've added second and third array of four 75amp-hour 12v batteries so I can have three 48v battery banks in parallel for a total of 225 amp-hours of power (115 usable amp-hours) at 48 volts.
adding a second charge controller
Consolidating my Solar in the Warehosue
Consolidating my Solar in the Warehosue
Consolidating my Solar in the Warehosue
I've taken the Nature's Generator all-in-one portable unit offline so I can use it elsewhere, and am running the entire building from my primary configuration.
Adding new East Facing PV Arrays
Consolidating my Solar in the Warehosue
Consolidating my Solar in the Warehosue
I have re-configured my solar panels so that I now have four arrays (sets of panels wired in series). Two 6-pannel arrays in parallel to my large charge controller, and two 4-pannel arrays in parallel to my small charge controller.
If I felt so inclined, I could add another 6-panel array or two in parallel behind my larger charge controller. I love having that capacity!
Using a Second Charge Controller
Using a Second Charge Controller
Using a Second Charge Controller
Why a separate charge controller? Charge controllers work best when dealing with similar inputs. The larger controller on the bottom is running two parallel arrays of four panels in series, all facing South. Adding East facing arrays that have three panels in series requires a second controller that can optimize for these new arrays, which is exactly what the smaller top controller is doing.
Synchronized Charging
Using a Second Charge Controller
Using a Second Charge Controller
So how do the batteries and controllers not get confused with two charge controllers sending power at the same time? While one controller is bulk charging, it would be counter-productive (even potentially damaging) if the other controller was in float-charge mode. Fortunately, Victron Charge Controllers have this neat feature wherein the two controllers can talk to each other and coordinate their charging modes, so my battery banks remain well cared for and not at all confused.