Designing Solar and Wind Hybrid System

Enclosed is a simple Hybrid system that I am using. I will explain some mistakes that I made as a beginner as we go along. 2000watts is the amount of power that I wanted my Hybrid System to support. The design I’m using is basically a combination of other designs I’ve found from researching the internet. When I determined my power needs and Charge Controller I was going to use, my system design would basically follow the manufactures suggested design. Below is to design I’m using and I will explain why I decided to implement it:



Basic Battery Storage

We need to start basic battery storage to help determine your system. The reason I’m using a 24volt, and not 12volt system, will be explained below by using the Power equation:

Watts=Voltage X Current

If you have 2000 watt daily use and are using a 12volt system:

Total average daily watts used _______________ / 12 = _____________________ Amps

2000w / 12v = 166.6 Amps or basically 170 amp/hr

Where if you are using a 24volt system:

Total average daily watts used _______________ / 24 = _____________________ Amps

2000w / 24v =83.3 Amps or basically 90amp/hr

That is your daily average Amp hours used.

So you need a battery storage bank that will allow you to have that many amp hours stored PLUS you want extra storage capacity for days with low sunshine when the solar panels will not fully recharge the system.

A general rule of thumb is to have enough storage capacity to last 3 days without sunshine in
the event you have very cloudy days and that way you can still run your appliances. If you do
not get many cloudy days or you get lots of cloudy days in winter you may want to adjust this
number up or down. We will use 3 days for this example. Batteries should not be discharged
below 50% of rated amp hours if you want them to last a long time!

If a US Battery145XC2 is rated for 251 amp hours at a 20 Amp discharge rate then it is actually a 125.5 amp hour battery at 50% discharge: 251 / 2 = 125.5

Since we want 3 days of storage capacity to cover low sun days in winter we multiply our
average daily amp hours used by 3 and from the example we used we get: 170 Amps X 3 Day =
510 amp hours Daily on a 12V system :

Average amps used ___________ X days of storage capacity desired ____________ = battery amp hours needed

For a 12volt- 2000w system:

From the example above we need 510 amp hours of storage and battery has 125.5 amp hours
at 50% so we need 510 / 125.5 = 4.06 or 5 batteries.

For a 24volt- 2000w system:

90Amps X 3 Days = 270 amp hours Daily. 270 / 125.5 = 2.15 or 3 batteries

This formula shows that if using a 24v system we will use less batteries than in a 12v system.  We can use the formula with any deep cycle battery as long as you know the rated amp hours!  The Sizing formulas given are for a very simplified way to determine a solar electric system that will work for most applications.

If batteries are hook in series the voltage will increase:


Since my system is 24V I used banks of 4 – 6V Golf Cart batteries (US Battery145XC2) then I added another bank to make sure I had enough juice to cover my appliances that would be attached to my system.


Another reason for a 24v system is the nature of solar panels. It was cheaper to get 24v panels than 12v and I could get more watts for the money.

Next important thing is the Charge Controller.

I designed my whole system around what Charge Controller that I would be using. For example, if I used a 60Amp Charge controller I will need to use enough Solar Panels to almost equal 60 amps.  When solar panels are hooked in parallel the voltage will stay the same but current will increase.  If solar panels are hooked in series the voltage will increase but current will stay the same:


Since I’m using a 60amp, with a 24v system, I would hook no more than six. Think of it this way.   I have 225 watt panels and if you hook six in parallel that would be 225+225+225+225+225+225= 1350watts total.  1350w/24v = 56.25 amps.  That’s different than adding straight current value from panels 8a+8a+8a+8a+8a+8a = 48a. A calculated estimate of 56.25 amps of current in system is assuming that all panels are equal. The limiting factor will be the weakest panel and the side effects are that everything in the solar array will reduce to that weakest panel’s specs.  Also, if leaves or shadows cover one panel in an array, everything reduces as well.

I found out that, in real life, you don’t really get the Power numbers that the math will show.
There are more detailed equations to get more precise numbers, but I just use simple formulas
for basic design purpose, and for my use that is all I needed.

There are several very good Hybrid Charge Controllers on the market today. The controllers
that I bought and used had to be easy to install and use, and purchased off Ebay or Amazon the
only place I like to shop. The Hybrid Charge Controller’s I used are:

Coleman Air C440-HVA …from Coleman, Texas…

Mountain Wind Trading Company 24v…from Mansfield, Missouri…

Xantrex C60 Solar and Wind turbine…Global…

30A PWM Solar Charge Controller 12/24 V … China

The controller I liked the best was the Coleman Air C440-HVA. It’s a 10,000 watt 440 amp system that can take 125amp on solar input and at least ten -1kw wind turbines on its wind input. That means it can handle a large personal Hybrid system.

large-hybrid-systemColeman Air also has a wide variety of solid state units that are 60a, 150a and 160a. All are able to handle a medium to large hybrid systems extremely easily.

My next favorite Hybrid controller is the 24v from Mountain Wind Trading Company.

mountain-wind-trading-systemUnlike the Coleman Air C440-HVA the Mountain Wind Trading Company comes with the three phase brake switch for one wind turbine and it comes with a dummy load to handle the access power easily. This controller also uses the monster 440a relay and is 10,000 watt capable, however designs look the same as Coleman air. This unit is also easy to install and be very scalable from a small up to about any size you want. Some of their new models are mounted in metal box just like the Coleman Air, which I think it’s important for larger system.  However, for small to mid size systems a case isn’t needed. This unit is about $75 cheaper than the Coleman and is ready to go straight out of the box. Special note, in the recommended design it doesn’t show blocking diodes on voltage inputs. On a small system it’s not as important, however, in a large Hybrid in think it might be a good idea to stop possible floating voltage or current through out the system.

The reason these two Charge Controllers are my favorites are due to the ability to handle a large
Hybrid systems and virtually have same design. I wanted to be able to start small and then expand to something that could run my RV completely off grid if I wanted.

The other Charge Controller that I used is completely solid state. One issue I have with solid state is that it handles a lower amount of current, however, it unit is easy to install and use. The picture below is the Xantrex C 60 Charge controller.






This controller can handle a what I consider medium size Hybrid system easily. There are some in field configuration. You must open the case and move jumpers, as well as, hook up a load to handle access power.

Documentation that comes with the unit explains clearly.  I had no issues with this unit and the only reason I’m not using it is because I wanted something that could handle larger amount of current.

The last Charge Controller I used was a simple 3oI or RENOGY 30amp solid state solar



This controller was was under $50 and will take a charge/load curcuit of 30a and will handle about 720watts running in 24v mode. This solid state and won’t take an inverter or heavy DC load like a motor but if you need a battery charging station or something light, it’s the way to go.



Now we have to talk about Power Inverters.  Inverters are more than likely the single most expensive part of your design.  Just like Charge Controllers there are quite a few out there.  Since, I knew I wanted to run about a 2000watt system I needed an Inverter that could handle at least 5000watt with a peak surgeof 10,000watts. I also investigated the difference between a Modified Sine and a Pure Sine Wave Inverter. Pure Sine Wave is more exspensive, however, I think it’s worth it. From the research that I did it appears the appliances, comuters, etc. run better on Pure Sine Wave and that there might be a heating problem from a Modified Sine Wave. Also, there might be some distortation in a computer screen and LCD televisions. I didn’t want to spend the money to test this theory, so I stayed with Pure Sine Wave.


For example, if you start up a 150watt TV the startup current can be up to 10 times, which means a short term maximum performance of 1500watts. If you use a weak or small Inverter it could damage your inverter and appliance. So I looked at several different brands:

Magnum Energy Inverter.  When Xantrex bought Trace a few key people started this company. I researched everywhere and this inverter had great spec’s.  So, I bought one. When it arrived I opened the box and determined very quickly this unit wasn’t for the beginner. Wiring diagrams for external AC outlets boxes and installation procedures were confusing. Even though on paper this inverter is exactly what I needed I couldn’t use it. Now after doing many different system installations, I can wire and install with confidence. Now I love and understand this very nice inverter and it’s one of finest on the market based in Everett, Washington.

Xantrex.  I like almost all their inverters part of Schneider Electric, I believe, base globally.  Almost every single power inverter could do what I needed it to do.. VERY NICE.

Outback Power.  This is an inverter that I have seen in designs, but haven’t installed. The OutBack modular system architecture allows your system to grow along with your power needs up to 36,000watts.  I will definitely make an attempt to set one up on my test base in the future, headquartered in Arlington, WA.

Morningstar.  Good inverter from what I read and what people told me. I have seen an installation but have not installed one personally. Documentation is clear and easy to follow. Company appears to be based Newtown, PA.

Power Jack Inverter.  Is the Pure Sine wave inverter I finally decided to use. It was easy to install which made it perfect for the beginner, and if you burned it up it was under $500 brand new. The other Power Inverters list above were in the $2000 and up range. Needless to say, your want to make sure your system design and appliance you use is rock solid before cooking $2000.The Power Inverter was a 24v -5000w with 10000watt surge. While testing and checking out appliances, I discovered the max wattage per appliance, that I could use, on this Power Jack inverter was:


My next project may be hooking two 24v inverters in parallel to help with short power surge on startup, but allow about the same power usage though out day. Or maybe two 12v inverters in series. Hmmmmm….. Sometime you just got to see if theory causes a melt down. I can hear wifey screaming about it already…..


Wind Turbines

Wind turbines are a nice additive for a system especially if you need power fast. I made sure all power needs were met with solar panels. They are simple and dependable and easy to calculate. Wind turbines are to be treated as excess power, to be used for different purposes such as a water heater or space heater, not everyday needs. I looked at many different types of wind turbines. Basically, there are two types, AC and DC. The main advantage of AC is that there will be less power lost from the turbine to Charge Controller. In DC, it means the rectifier is located in the turbine itself instead of down by the charge controller. In a AC or DC turbine the power is generated the same way. It will be a Permanent Magnet spinning around inside a coiled wire.


And current will be created. I decided on a dual PMA design (picture is above), because if I have to install a tower and a wind turbine I wanted to get double power. With double output I have to have double wire coils. Since I also used AC it means three wire are coming down from each wire coil, then into a rectifier by my charge controller. Then I wire rectifiers in series for a 24v system.  MAKE SURE THE OUTPUTS GO TO RECTIFERS FIRST before wiring together.  ANOTHER IMPORTANT NOTE NEVER LET WIND TURBINE SPIN UNATTACHED to a load, because serious damage could occur to turbine. Once again there are many different PMA manufactures out there and I couldn’t check them all out at this time.  I have checked the turbines from Missouri Wind and Solar, as well as, from Midwest Wind Power (Midwest maybe out of business now, bought my turbines in 2012). I bought both of them off Ebay. I like the Midwest WindPower a little better and it appears to be solid and it’s spec’s were closer to what the manufacture stated.  I didn’t get what was advertised from Missouri wind and Solar. I would like to try a new company I saw on Ebay called Hurricane Windpower. I’m watching their videos with a meter and they appear to genuine. BEWARE OF SOME MANUFACTURES CLAIMS you will be lucky if you can get an output of about 1kw per turbine , in 40-50 mph winds.  If they say they get more than that, I would’t believe them, unless the turbine has more magnets and also has a larger diameter. The turbines I have been using have the same diameter and size as a GM alternator which means there is only so much you can from something that size. and I didn’t want to try and divert access power for anything larger than 1kw – 2kw at this time. Although I’m looking into hot water design with 2 or 3 – 600w-24v elements mounted on a 55 gal drum full of water, would definitely provide a good load.

In closing, I have had a lot of fun with the several separate Hybrid Systems I have, and will attempt to update this site with different projects or products, as I complete my tests. I have stayed with the “Off Grid” designs mainly to keep away from “On Grid” rules. If you are using the POWER GRID as your load to remove or sale access power from your system you must be able to verify no power leaves your system into POWER GRID if it goes down. Let’s say your turbines generating 5kw extra because the wind is blowing so hard that it’s blowing down power lines. That means 5kw is leaving your home going to a “step up” transformer on your utility pole, and from there to a power company’s guy working on the downed power lines. It would really suck to be him. I hope my research, information, and errors will help you with your designs, if you decide to continue with your Solar and Wind Hybrid project.

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