Hi, I’m Amy from the altE Store. Are you interested in a DIY off grid solar system?
That’s great news! The altE Store has sold solar systems to every continent on the planet
And we're still making renewable do-able since we started in 1999.
Here are the 6 steps you need to take to get started.
#1 Figure out how much power you need This is the most important step, and yet many
people try to skip over it. Don’t. Planning a solar system without knowing how much power
you need is like planning a car trip and not knowing how far you are going, and in what
vehicle. Ok, now go buy gas for the trip. How much? Well, that depends on your distance
and gas milage. Same with solar. You can’t just say I’m going to buy a couple of solar panels
and a battery and hope it will be enough for my needs. Go to our loads list calculator and enter
what you will be powering with your solar power system. You’ve got to remember absolutely
everything that will be powered by your system. Seemingly little changes can make a big difference.
For more details on making a loads list, watch our video Off Grid Solar Power
System Design - Step 1 here,
#2 Calculate the amount of batteries you need Now that you know how much power you need,
you need to figure out how many batteries you need to store it. Do you need only enough
storage for a day or two, do you have another power source like a generator or turbine that
will kick in if the sun doesn’t shine, or do you need to have enough batteries to store
3 or 4 days, or more, worth of power? Will you be storing the batteries in a warm room,
or will they be in a cold location? Batteries are rated for storage at around 80 degrees
fahrenheit, the colder the room, the bigger the battery bank you need to compensate, by over
50% more for below freezing. Each of these answers affects the size, and cost, of your battery bank
What voltage battery bank do you need, 12V, 24V, or 48V ? Generally, the larger the system,
the higher voltage battery banks are used to keep the number of parallel strings to
a minimum and reduce the amount of current between the battery bank and the inverter.
If you are just having a small system, and want to be able to charge your cell phone
and power 12V DC appliances in your RV, then a basic 12V battery bank makes sense.
But if you need to power much over 2000 watts at a time you’ll want to consider 24 volt
and 48 volt systems. Besides reducing how many parallel strings of batteries you’ll
have to have, it’ll allow you to use thinner and less expensive copper cabling between the
batteries and the inverter.Go to our off-grid calculator to calculate what size battery
bank you need based on these answers.
If you want to learn more about sizing the battery bank yourself, watch our video
Off Grid Solar Power System Design - Step 2 here. We’ve got a big selection
of battery types and sizes here.
#3 Calculate the number of solar panels needed for your location and time of year
Now you can figure out how much solar power you need. The second half of our off-grid
calculator can help you figure out how many solar panels you’ll need for your solar system.
After knowing how much energy you need to make per day from the load calculator,
you’ll need to tell it how much sunshine you’ll have to harvest from.
This available energy from the sun for a location is referred to as “sun hours”.
The number of “sun hours” is basically how many hours the available sun shining on
your panels at an angle throughout the day equals sunlight as if it were shining directly
on your solar panels when they get the most power, like at noon. As you know, the sun isn’t as bright
at 8AM as it is at noon, so an hour of morning sun may be counted as half a sun hour, where
the hour from noon to 1PM would be a full sun hour. And unless you live near the equator,
you do not have the same number of hours of sunlight in the winter as you do in the summer.
You want to take the worst case scenario for your area, the season with the least amount
of sunshine that you will be using the system. That way you do not end up short on solar
energy part of the year. If it’s a summer camp, you don’t need to plan for winter,
but if it is a year round home, or a hunting cabin, you need to tell it the number of sun
hours that correspond to winter. Luckily, it’s easy to figure out the sun-hours for
anywhere in the world with our calculator or using sun-hour maps. If you are planning
on year round in the USA, enter the city nearest you from the dropdown menu. If you are elsewhere
in the world, we have some maps you can use for reference here and enter the sun hours.
The calculator will tell you how many watts of solar panels you need for your system.
For more details on sizing your solar array, watch our video Off Grid Solar Power System Design - Step 3 here.
We’ve got a large selection of solar panels of different voltages and wattages here.
#4 Select a solar charge controller Alright, so we have batteries and we have
solar, now we need a way to manage putting the power from the solar into the batteries.
An extremely rough calculation to figure out what size charge controller you need is to
take the watts from the solar, in our example here it was 500W, and divide it by the battery
bank voltage, in this case 24V. That gives us 21A. Add another 25% for a safety factor,
and you’re going to need a charge controller that can handle at least 26 amps.
so we'll probably round up to a 30A charge controller.
Now there’s also a bit more to consider with selecting the charge controller.
Charge controllers are available with two major types of technologies, PWM and MPPT.
We’ve done a video explaining the difference between the two, you can see that here.
But in short, if the voltage of the solar panel array matches the voltage of the battery bank,
you can use a PWM charge controller. So if you have a 12V panel and a 12V battery bank,
you can use PWM. If your solar panel voltage is different than the battery bank, and can’t
be wired in series to make it match, you need to use an MPPT charge controller. If you have
a 20V solar panel and you have a 12V battery bank, you need to use MPPT. To see more on
how to size the different options, go watch Off Grid Solar Power System Design - Step 4.
We carry both PWM and MPPT solar charge controllers here.
#5 Select an Inverter Now that we have efficiently charged batteries,
we need to make the power usable. If you are only running DC loads straight off your battery
bank, you can skip this step. But if you are powering any AC loads, you need to convert
the direct current from the batteries into alternating current for your appliances. It
is very important to know what type of AC power you need. If you are in North America,
the standard is 120/240V split phase, 60Hz. In Europe and much of Africa and some countries
in South America, it is 230V single 50Hz. In some islands, it is an interesting mixture
of both. Some inverters are configurable between voltages and/or frequencies, many are fixed.
So check the specs carefully of the inverter you are interested in to make sure it matches
your needs. If you do have the North American standard, you must figure out if you have
any appliances that use 240V, or if they are all just 120V. Some inverters are able to
put out 240V, and you can wire the output to use either 120V or 240V. Other inverters
are stackable, each one outputting 120V, but when wired together, or stacked, can create
240V. And others are only capable of outputting 120V, and cannot be stacked. Again, read the
specs to determine which inverter is right for you.
You also need to know how many watts total your inverter will need to power. Luckily,
way back in step one, you created a loads list that figured out both the constant watts
and surge requirements of your loads. Please note that an inverter is designed for
a specific voltage battery bank, like 12, 24 or 48 volt. They are not field selectable.
So you need to know what voltage battery bank you are going to have before you settle on
the inverter. Keep this in mind if you think you may be growing your system in the future.
If you plan on having a higher voltage battery bank later, be aware that the lower voltage
inverter won’t work in the new bigger system. So either plan ahead and go with the higher
voltage to begin with, or plan on changing out your inverter in the future.
For more details on selecting inverters, see our video Off Grid Solar Power System Design - Step 5.
We carry inverters for North America and the Rest of World with
a variety of votage and wattages here.
#6 Balance of System OK, yes, I’m kind of cheating by lumping
everything else into one step for balance of system, but there are a lot of other little
components needed, like the fuses and breakers for over current protection, what breaker
boxes will you use, how are you going to mount the solar panels, what size wire do you need?
We’ve got more videos that can help you out with a lot of those details, like
Solar Power Components - Part 4 and
Wiring Your Solar Power System. We’ve also created some off grid solar kits that have
a lot of the Balance of System already selected. You can see them here. Since solar really
isn’t one size fits all, they can be a great starting point to your own custom solar system.
Once you’ve gone through these 6 steps, you’ll have a great start to designing your
own DIY solar system. Give us a call with any questions, or if you want help designing
a system. Also check out more of our videos here for more details. If you found this video
to be informative, please like and share the video, and subscribe to our channel ,altE Store .
Also go to our website at altestore.com, where we’ve been making renewable doable since 1999.