Day by day the price of the solar panel falls gradually.But still installation of a complete off grid solar system is costly.So I write this instructable to get all the components of your solar system separately and assemble it all by yourself.

See my new instructable ARDUINO MPPT SOLAR CHARGE CONTROLLER ( Version-3.0)

If you are decided to install a solar panel system to cover your home power needs.This tutorial is for you.

I have tried my best to guide you step by step from buying different components to wiring everything by yourself.

Only you have to know some basic electrical and math for designing the entire system.Instead of this I have attached links of my other instructables to make the charge controller and energy meter.

For a off grid solar system you need four basic components

1. Solar Panel (PV Panel)

2.Charge Controller

3. Inverter


Besides the above components you need few more things like Copper Wire, MC4 Connector,breaker,meter and fuses etc.

In the next few steps I will explain in details how you can choose the above components according to your requirement.

Note : In the picture I have shown a big solar panel of 255W @ 24V , two batteries of 12V @ 100Ah each, 30A @ 12/24V PWM solar charge controller and a 1600 VA pure sine wave inverter.But during the calculation I have taken a smaller solar system example for better understanding.


Before choosing the components you have to calculate what is your load , how much time it will run etc.If any one know basic maths then It is very simple to calculate.

1 .Decide what appliances (light,fan,tv etc ) you want to run and how much time (hour).

2. See the specification chart in your appliances for power rating.

3.Calculate the Watt Hour which is equal to product of power rating of your appliances and time ( hr) of run.

Example :

Lets you want to run a 11W CFL for 5hour from solar panel,then the watt hour is equal to

Watt Hour = 11W x 5 hr = 55

4.Calculate the total Watt Hour : Just like a CFL calculate the watt hour for all the appliances and add them together.

Example :

CFL =11W x 5 hr = 55

Fan = 50 W x 3hr = 150

TV = 80W x 2hr = 160


Total Watt Hour = 55+150+160 = 365

Considering 30% energy lost in the system.

So total Watt Hour per day = 365 x 1.3 = 474.5 Wh which can be round off to 475 Wh

Now the load calculation is over.The next thing is to choose the right components to match with your load requirement.

If you are not interested to doing the above maths then use a load calculator for this calculation.There are huge number of load calculator available in the internet.I am attaching a such link Off Grid Load Calculator.



The Solar Panel converts the sunlight into electricity as direct current (DC).These are typically categorized as

mono crystalline or poly crystalline.Mono crystalline are costlier and efficient than poly crystalline panel.

Solar panels are generally rated under standard test conditions (STC): irradiance of 1,000 W/m², solar spectrum of AM 1.5 and module temperature at 25°C.


The solar panel size should be selected in such way that it will charge the battery fully during the one day time.

During the 12hr day time the sunlight is not uniform it also differ according to your location in the globe.So we can assume 4 hours of effective sunlight which will generate the rated power.

Total Wp of PV panel capacity needed = 475Wh /4 = 118.75 W

By taking some margin you can choose a 120 Watt ,12v solar panel.

Here you should not confuse with the 12V. I wrote 12V as it is suitable for charging the 12V battery.But actually the Solar panel voltage is around 17V or more.



The out put from the solar panel is dc power.This power is generated during the day time only.So if you want to run a dc load during day time then it seems to be very easy.But doing this is not a good decision because

>> Most of the appliances need a constant rated voltage to run efficiently.Solar panel voltage is not constant it varies according to the sun light.

>> If you want to run the appliances during night then it is impossible.

The above problem is solved by using a battery to store the solar power during the day time and use it according to your choice .It will provide constant source of stable, reliable power.

There are various kind of Batteries. Car and bike batteries are designed for supplying short bursts of high current and then be recharged and are not designed for a deep discharge. But the solar battery is a deep-cycle lead-acid battery that allows for partial discharge and allows for deep slow discharge.Lead acid tubular battery is perfect for a solar system.

Ni-MH batteries and Li-Ion batteries are also used many small power application.

Note : Before going to choose the components decide your system voltage 12/24 or 48 V.Higher the voltage lesser the current and lesser will be the copper loss in the conductor.This will reduce your conductor size also.In most of the small home solar system have 12 or 24 V.

In this project I am selecting the 12 V system.


Batteries capacity are rated in term of Ampere Hour.

Power=Voltage X Current

Watt Hour =Voltage (Volts) x Current (Amperes) x Time (Hours)

Battery Voltage = 12V ( as our system is 12V)

Battery capacity= Load /Voltage = 475/12 = 39.58 Ah

Practically battery are not ideal, so we have to consider the loss.Let the battery loss is 15%.

So battery capacity required is 39.58 / 0.85 =46.56 Ah

For better battery life,they are not allowed to discharge fully (100% ).For flooded lead acid battery 60% depth of discharge (DOD) is considered as good practice.

So Capacity Required = 46.56 /0.6 = 77.61 Ah

You can select a deep cycle lead acid battery with capacity more than 77.61 Ah.

You can round off to 80 Ah



A solar charge controller is a device which is placed between a solar panel and a battery. It regulates the voltage and current coming from your solar panels .It is used to maintain the proper charging voltage on the batteries. As the input voltage from the solar panel rises, the charge controller regulates the charge to the batteries preventing any over charging.

Usually, the solar power systems uses 12 volt batteries, however Solar panels can deliver far more voltage than is required to charge the batteries. By, in essence, converting the excess voltage into amps, the charge voltage can be kept at an optimal level while the time required to fully charge the batteries is reduced. This allows the solar power system to operate optimally at all times.

Types of Charge controller :


2. PWM


Among the 3 charge controllers MPPT have highest efficiency but it is costly.So you can use either PWM or MPPT.

MPPT Charge Controller is most effective under these conditions :
1. Cold weather, cloudy or hazy days

2. When battery is deeply discharged

Try to avoid the ON/OFF charge controller as it is the least efficient.


Since our system is rated 12V, Charge controller is also 12V

Current rating = Power output of Panels / Voltage = 120 W/ 12V = 10 A

By taking 30% margin, You can choose a 13A charge controller. But the next rating controller available in the market is 20A. So choose a Charge Controller of 12 V and current rating of 20.0 A.

Note : If you get 15A Charge Controller,then also it work.

If you like to reduce your system cost you can make a PWM charge controller.For step by step instruction you can see my instructable on PWM CHARGE CONTROLLER.

You may also like my new design on solar charge controller.



Solar panel (PV) that receive the sun’s rays and convert them into electricity called direct current (DC). DC is then converted into alternating current (AC) through a device called an Inverter. AC electricity flows through every outlet of your home, powering the appliances.


1. Square Wave

2. Modified Sine Wave

3. Pure Sine Wave

Square wave inverter is cheaper among the all but not suitable for all appliances.Modified Sine Wave output is also not suitable for certain appliances, particularly those with capacitive and electromagnetic devices such as: a fridge, microwave oven and most kinds of motors.Typically modified sine wave inverters work at lower efficiency than pure sine wave inverters.

So as per my opinion choose a pure sine wave inverter.

It may be grid tie or stand alone .In our case it is obviously stand alone.


The power rating should be equal or more than the total load in watt at any instant.

In our case the maximum load at any instant = Tv (50W) +Fan (80W) +CFL (11W) =141W

By taking some margin we can choose a 200W inverter.

As our system is 12 v we have to select a 12V DC to 230V/50Hz or 110V/60Hz AC pure sine wave inverter.

Note :

Appliances like fridge,hair drier,vacuum cleaner,washing machine etc likely to have their starting power consumption several times greater than their normal working power (typically this is caused by electric motors or capacitors in such appliances). This should be taken into account when choosing the right size of inverter.



After design the solar system.Buy all the components with appropriate rating as per the previous steps.

Now it is time to mount the solar panel.First choose a suitable location on the roof top where there is no obstruction sunlight.

Prepare the mounting stand : You can make it by your own or it is better to buy one from any store.In my case I have taken the drawing from the solar panel company and made it at near by welding shop.The tilt of the stand is nearly equal to the latitude angle of your location.

I made a small wooden mounting stand for my 10 Watt solar panel.I have attached the pictures,so that any one can made it easily.

Tilting : To get the most from solar panels, you need to point them in the direction that captures the maximum sun light.Use one of these formulas to find the best angle from the horizontal at which the panel should be tilted:

>> If your latitude is below 25°, use the latitude times 0.87.

>> If your latitude is between 25° and 50°, use the latitude, times 0.76, plus 3.1 degrees.

For more details on tilting click here

First place the stand in such a way that the face is directed towards south.Mark the leg position over the roof.

To get the south direction use this android app compass

Then make rough surface at each leg of the stand by using a sharp object.I made around 1Sq feet size rough surface over the roof at each leg.This is helpful for perfect bonding between the roof and concrete.

Prepare concrete mix : Take cement and stones with 1:3 ratio then add water to make a thick mix..Pour concrete mix at each leg of the stand.I made a heap shape concrete mix to give maximum strength.

Mounts the panels to the stand : At the back sides the solar panel have inbuilt holes for mounting.Match the solar panel holes with the stand/platform holes and screw them together.

Wire the solar panel : At the back sides of the solar panel a small junction box is there with positive and negative sign for polarity .In a large size solar panel this junction box have terminal wires with MC4 connector but for small size panel you have to connect the junction box with external wires.Always try to use red and black wire for the positive and negative terminal connection.If there is provision for earth wire the use a green wire for wiring this.



After the calculating the battery capacity and solar panel rating you have to wiring them.In many cases the calculated solar panel size or battery is not readily available in the form of single unit in the market.So you have to add small solar panel or batteries to match your system requirement.To match the required voltage and current rating we have to use series and parallel connection.

1. Series Connection :

To wire any device in series you must connect the positive terminal of one device to the negative terminal of the next device.The device in our case may be solar panel or battery.

In series connection the individual voltages of each device is additive.

Example :

lets 4 12V batteries are connected in series, then the combination will produce 12 + 12 + 12 + 12 = 48 volts.

In series combination the current or amperage is same.

So if these devices were batteries and each battery had a rating of 12 Volts and 100 Ah then the total value of this series circuit would be 48 Volt, 100Ah. If they were solar panels and each solar panel had a rating of 17 volts(Osc voltage) and were rated at 5 amps each then the total circuit value would be 68 volts, 5 amps.

2. Parallel Connection :

In parallel connection you must connect the positive terminal of the first device to the positive terminal of the next device and negative terminal of the first device to the negative terminal of the next device.

In parallel connection the voltage is remain same but the current rating of the circuit is sum of all the devices.

Example :

Lets two batteries of 12v,100Ah are connected in parallel then the system voltage is remains 12 volts but the current rating is 100+100=200Ah. Similarly if two solar panel of 17V and 5 amps are connected in paralel then the system will produced 17 Volts ,10 amps.



I made the above inverter and battery stand by the help of a carpenter.The design idea I got from this instructable.The design is really helpful for me.

At the back side I made a big circular hole just behind the inverter fan for fresh air suction from out side .Later I covered the hole by using plastic wire mesh.Few small holes are also made for inserting the wires from solar panel,charge controller and inverter to the battery and ac out put to the appliances.At the both sides panel 3 horizontal holes are provided for sufficient ventilation. A glass window is provided at the front side to view the different led indications in the inverter.

In the inclined plane of the inverter stand I have mounted the charge controller.In future I will installed my own made energy meter also.

Step 9: WIRING

Picture of WIRING

The first component we are going to wire is the Charge Controller.At the bottom of the Charge Controller there are 3 signs in my charge controller. The first one from the left is for the connection of the Solar Panel having positive (+) and negative (-) sign. The second one with plus (+) and minus (-) sign is for the Battery connection and the last one for the direct DC load connection like DC lights.

As per charge controller manual always connect the Charge Controller to the Battery first because this allows the Charge Controller to get calibrated to whether it is 12V or 24V system. Connect the red (+) and black (-) wire from the battery bank to the charge controller.

Note : First connect the black /negative wire from the battery to the charge controller's negative terminal ,then connect the positive wire.

After connecting the battery with charge controller you can see the Charge Controller indicator led lights up to indicate the Battery level.

After connecting this inverter terminals for battery charging is connected to corresponding positive and negative terminals of the battery.

Now you have to connect the solar panel to the charge controller.At the back side of the Solar Panel there is a small junction box with 2 connected wires with positive(+) and negative (-) sign.The terminal wires are normally smaller in length.To connect the wire to the charge controller you need a special type connector which is commonly known as MC4 connector.See the picture.After connecting the solar panel to the charge controller the green led indicator will light if sunlight is present.

Note : Always connect the Solar Panel to Charge Controller while facing the Panel away from the sun or you may cover the panel with a dark material to avoid sudden high voltage coming from the solar panel to the Charge Controller which may damage it.


It is important to note that we are dealing with the DC current. So the positive (+) is to be connected to positive (+) and negative (-) with negative (-) from Solar Panel to Charge Controller. If it gets mixed up, the equipment can go burst and may catch fire. So you need to be extremely careful when connecting these wires. It is recommended to use 2 color wires i.e. red and black color for positive (+) and negative (-).If you don't have red and black wire you may wrap red and black tap at the terminals.

Connect the dc load or dc light at last.

Additional Protection :

Though charge controller and inverter have inbuilt fuses for protection, you can put switches and fuses in the following places for additional protection and isolation.

1. In between solar panel and charge controller

2. In between charge controller and battery bank

3. In between battery and inverter

Metering and Data logging :

If you are interested to know how much energy is produced by your solar panel or how much energy being consumed by your appliances you have to use energy meters.

Besides this you can monitor the different parameters in your off grid solar system by remote data logging

For diy based energy meter you can see my instructable on ENERGY METER which have both metering and data logging capability.

After wiring every thing the off grid Solar system is ready for use.

Thank you for reading my instructable.


JasonO78 (author)2018-01-22

Is there any way to build a system that pulls from a battery first, and then would pull from the grid after you used up all the electricity that got stored throughout the day from solar?

vinyke (author)2018-01-18

Nice tutorial. Very instructive. Thanks

ManuelG133 (author)2017-12-15

Best tutorial in the internet. Thanks a lot.

flexihopper18 (author)2017-12-05

Great tutorial :) Thank you

RayC121 (author)2017-11-24

What a great explanation. I learned a lot from this article. Thank you.

rohanize (author)2017-10-20

well explained sir

JennyHamann (author)2017-10-17

I have a house in Puerto Rico and the grid is dead there. I know only the little bit I've read about off grid power and want to get my house up and running as efficiently and economically as possible but want to make it a decent enough system to expand and continue even if/when our area has grid capable service again. I'd rather not ever be dependent on the grid again. I like the idea of the NiFe batteries. I'm not always there to maintain a system with finicky batteries. Once up, I need a fairly carefree system. Also, I need the system to be modular so that I can remove panels when dangerous storms are coming. Can a system be made for quick disassembly and reassembly before and after major storms?

hycart (author)2017-09-06

You have not mentioned NiFe (Nickel Iron)
Batteries as a storage option.

I have gone off the grid because of the antics of our power companies. I have a 10 kW solar array, SMA Sunny Island 8.0
Inverter/Charger/Controller, 2 X 5 kW SMA Sunny Boy inverters, and 40 X 2
Volt NiFe 600 amp hour batteries, providing 48 volts. According to the
manufacturer I have approximately 3 days autonomy. I also have a diesel 20 KVA generator as backup in case the sun goes off line. The generator is able to charge the batteries or run the house, so there is no loss of power should I need to isolate the batteries for maintenance or any other reason.

The batteries cost a
bit more, but for anyone interested in doing their own research, there
are Nickel Iron batteries built in the early 1900s that are still in use today.
Overcharging and 90% DOD have no detrimental effect on these batteries. They do not achieve full potential until they run through about 50 cycles.

This link will take you to an Australian site. The menu at the top will take you through the site-

me, Lithium Ion batteries have not been around long enough, and the
long term effects/benefits/problems are not known. I don't believe that
Tesla's Power Wall is as good or efficient as they are touted to be.

acid is not the greatest technology for storage, given that DOD is
around 20% before shortening battery life, and overcharging has an even
more detrimental effect. Lead acid would need to be replaced regularly,
some say 6 to eight years, but for this post, I will assume 10 year
life span before needing replacement.

Bottom line is that I have
spent almost $20K for my batteries, but I will never have to replace
them in my life time, and I don't believe my children will have to
replace them either, and possibly the grandchildren as well.

I would be interested to hear any comments.

JennyHamann (author)hycart2017-10-17

I have a house in Puerto Rico and the grid is dead there. I know only the little bit I've read about off grid power and want to get my house up and running as efficiently and economically as possible but want to make it a decent enough system to expand and continue even if/when our area has grid capable service again. I'd rather not ever be dependent on the grid again. I like the idea of the NiFe batteries. I'm not always there to maintain a system with finicky batteries. Once up, I need a fairly carefree system. Also, I need the system to be modular so that I can remove panels when dangerous storms are coming. Can a system be made for quick disassembly and reassembly before and after major storms?

shreeram_joshi (author)2017-10-16

I too want to join this bandwagon. Currently I have a grid tie system of two Sunny Boy 5Kw invertors and 30 Solar PV panels delivering 9.8 KW DC. All in all I get 8 KW AC from the invertors. Looking forward to integrating NiFe battery bank to complete my system. Would appreciate any pointers.

diygeo (author)2017-07-31

Great summary. However it would be useful to know approximate costs of various options and vendors, fully realizing that in most cases stuff will only get cheaper.


rinohartetc (author)2017-07-06

Is there a battery for an off grid system that will power a 220v appliance?

Tomas Jansen (author)2017-02-27

Hi. If you want to build it yourself just google for 'inplix' . I know you'll find good solutions for your idea.

Thanks for tip

frisbrob (author)2016-10-12

Hey, one thing i see all the time with solar projects is all anybody uses is 12v deep cycle batteries. These batteries were mostly meant for boats, high cranking amps and could be discharged more without killing the life of the battery. The best battery to use is deep cycle 6v batteries wired in series to give you one big 12v battery. If you want lots of power stored for longer use, use 6v batts. Another thing that you need to think of if you are going off grid is your solar array needs to be big enough to not only run the things you want but also put out enough power to recharge the batteries at the same time or each time you start to use the batteries they will just be drained more and more until they are dead. System needs to be bigger than for just running the house. If you are totally off grid then your system needs to keep the batteries charged the whole time the house is draining power. Same thing either way you look at it.

KingsleyI4 (author)frisbrob2017-02-07

Thanks for the information, please i have a question if i am to use 2 6V instead of 1 big 12v battery, does the AH size matters? what i am interested in is getting lots of power power stored for longer use.

sunsolutionssa (author)2017-01-22

As a vendor of DIY off grid solar systems, these notes are excellent! In fact we use ones that are very similar when calculating loads. Feel free to compare with our site Good luck to all and thank you for getting off the grid and doing your part to help the planet and your wallet!

Heisy (author)2017-01-06

Awesome definitely will use your notes to guide me set up my solar power system.

73wayne (author)2016-12-31

hi. I have a ups and I want to know if it canbe used instead of buying a new inverter.

foofoodog (author)2016-04-26

AGM deep cycle batteries should only be taken to 50% depth of discharge to maximize battery life span. Your example math assumes it will be 100% DOD and that will destroy the battery in a very short time.

Battery amp hours are normally quoted at a 20 hour rate for greatest efficiency. So a 35 Ah battery at that rate will give you 1.75 amps an hour or 21 watts an hour at 12 volts. Expect only 50% of that to be usable without trashing the battery.

Running a 200 watt inverter full bore from a 35 Ah battery will last about an hour and also destroy the battery quickly. At the 1 hour rate you can expect about 300 watts and your inverter will be tripping the low voltage shutoff alarm very quickly.

For comparison a 180 watt cigarette lighter plug car inverter circuit would need a 15 amp fuse and you would only use it with the car running and with enough spare capacity from the alternator.

For your example you will probably want 2 35 Ah batteries to go with your 125 watt panel to maximize battery lifespan. If you need to pull the full 200 watts for any length of time you will need a whole lot more battery and hence more solar.

TJLee089 (author)foofoodog2016-11-10

Actually the battery will have more than rated capacity at current draws less than the 20 hour rate due to the Peukert effect. The reverse is true as well.

Also, "watts an hour" is meaningless. A watt is a measure of power, which is energy per unit time, already a rate of energy flow.

TJLee089 (author)2016-11-10

If the loss is 30%, the correct calculation is 365/(1-0.3)=521 (not 475). This is 10% more than the calculation shown.

matt.carrasquillo (author)2016-11-04

I already know about components like Solar Panels, Charge Controllers, etc. But the wires and fuses I don't quite understand entirely. What Gauge do I need to buy? What sizes, lengths? Where do the fuses need to go? What kind of fuses do I need to buy do then need to be different Amp fuses or all the same Amp? Do you have to modify and cut cords in order to connect them to Charge Controllers or do they sell them premodified so you don't have to cut them yourself? These are the things nobody ever explains!

krbijoypal (author)2016-09-08

Per day 7 unit electricity consumption based calculation needed. I think 7 unit electricity consumption means 7000 watt by 24 hour. how many 250watt Solar panel, how many 12 volt battery, which charge controller and what capacity Inverter needed. With the above requirement please provide calculation step by step.

krbijoypal (author)2016-09-07

In our electricity bill we found unit consumed. Is it possible to take that to revere calculation for requirement of Solar panel, battery, and inverted ? If so plz guide.

MAXREMI (author)2016-09-02

Hello, I have a question about powering a security camera with a 12V battery. If I trickle charge the battery with a solar panel will it work? The cameras are dual voltage 12v dc or 24v ac

Ravundra Pardeshi (author)2016-07-18

Hello, I want to power 150 watt 220 volt heater with solar panel without using batteries. Can you Help in configuring it? Please help. Also I am interested in Grid sharing inverter. Any good model made in India

This is hard to do without having batteries, you need to regulate the voltage VERY accurately to power things directly. This will depend on the sun position, panel angle, etc. You'd have to find some sort of controller or regulator and have many solar panels to power things directly. I'd highly recommend you just finding some used deep cycle 12v batteries to act as a buffer and power soak.


There are alternatives perhaps, if you want to power a heater (meaning a unit to keep your house warm), you could build yourself a solar water heating system and a solar/battery powered pump and build a radiator type system with water that would be maybe more cost effective than powering a 220v electric heater

TUSHARKHANVILKAR (author)2016-04-27

very nice... why not you post about hybrid system.

deba168 (author)TUSHARKHANVILKAR2016-06-07

I will definitely write in future.

Thanks for the suggestion.

DanielV167 made it! (author)2016-06-04

Following this guide and a few others, I was able to do the following on a boat dock:

deba168 (author)DanielV1672016-06-04

Nice !
Thanks for sharing the pictures.
I am really happy to know that this guide help you .

Angelalbrown7 (author)2016-04-29

i want to power my whole trailer. 16X80 three b two b and live off grid completely. I don't want pay the electric company or for the water company. I wanna find a way to get power and water naturally from the earth the way it was meant. Please lemme know if y'all have any suggestions thanks

Subrahmanyam Gadepalli (author)2016-04-27

One of the possible mistakes any Solar enthusiast makes is to invert the DC power generated by Solar Photovoltaic panels to 220 or 110 Votls AC. When you do it, you lose half the efficiency. On the other hand, if the solar power generated is stored in a battery and used in the same voltage as it is stored, by having DC appliances, the economies are pretty good. Only problem is that you have to get these appliances anew, more over they are not that easily available off the shelf. At least, I am using a 70 watt panel, a charge controller, a 90 ah battery, two LED tube lights of 10 watts, and one pedestal fan of 22 W, all working on 12 V DC for nearly last four years, without hitch.

JamesAUS (author)2015-12-01

hi I have bought a pool heater and wanted to use off grid solar to operate it(ecosmart pool 27). Problem is the amperage draw of 112.5amp. can anyone give me advise as to how I could do this in a cost efficient way? Please

This is some info

3 elements


frequency 60Hz

power input 27kw

each supply 9kw

required breaker 3*50amp

recommended 200amp

Double pole breakers 6 * 50

Before installing this product, ensure that you have sufficient electrical power available to handle the maximum amperage load of the applicable model. ALL UNITS HAVE A 3 MINUTE TIME DELAY ONSTART.

I will appreciate any/all feedback on this.


Robert61 (author)JamesAUS2016-04-26

Your electrical needs are too great for a solar system to outright power the heater, so you have to find a way to save or sell the power from the solar array. Your 240v 112.5amp system is as big as a system for an entire house. You might want to consider a thermal hot water system for your pool heater (the kind of system that has black water pipe on the roof of houses), it would be less expensive. If you want to do it using solar, either your system has to be big enough to power the peak load of the heater, which would require a 27kWh (kilo Watt hour) solar array, (3 to 7 kWh is normal for a house) or you will need a normal sized array with a battery system to store the power to power the pump which would require huge batteries (Also expensive)

One other choice is to have a 5-7kWh solar system, and sell the power to the utility company, and run the pool heater at night when electricity is cheap and have your electric bill for your heater and house be paid for by the power you sell to your utility company. You can do this if your utility has a "Net Energy Metering" available. Or you could put in a small unit to just pay for the heater, of about 2 to 4 kW. and pay your house electric bill. The size needed depends on how much you run the heater, and how hot you keep the water.

Your formula to figure out what you will need is 240v X 112.5amps X (number of hours pool heater runs each day) = total kWh needed daily for your pool heater. Solar systems are rated in kW and should provide power for about 5 hours per day on average. So divide the kWh needed for the pool heater, by 5 hours per day of Sun, and that is the size in kW of the solar array needed to just cover the electricity for the pool heater. You should adjust the 5 hours of light to better reflect the sun in your area.

WhyMeLord (author)JamesAUS2016-04-26

Best is a direct solar to pool water heater. Cheaper and more efficient. There are a few simple DIY systems on Instructable. They can be either gravity or pump driven depending on the elevation involved.

timmg08 (author)JamesAUS2015-12-11

That is a lot of power. The gist thing that comes to my head is to scrap the heater and invest in a solar water heater. hearing the water directly with the Sun is far more efficient then trying to use pv. If you don't get enough Sun for that then I'd say you're next best bet would be to get a grid the system and skip the batteries. you can buy the panels over time to get more power and offset the power consumption of your water heater.

Wapata (author)2016-02-01

You don't talk about costs.

I wonder if i can build such system to power the laundry machines during day time, and water-heater too. And why not the kitchen during good sunny days ? I'll do the math, but in your opinion, these motor and resistives machines could be power securely with this home made system ?

WhyMeLord (author)Wapata2016-04-26

There are such appliances available for folk that live 100% off grid. They are efficient but NOT cheap.

Most economical is back feed to the grid. Some states (Texas comes to mind) with net billing. Works great for both the power company and the end user.

Other states ALEC and the power companies have convinced the legislature to make the idea economically impractical.

Wapata (author)WhyMeLord2016-04-26

Yeah i know some of theses. SMA for example, or "the kodiak" (very new), or Tesla.

I"ve worked with SMA company, it's reliable, not cheap.

My question was more "is it really secure" ?

WhyMeLord (author)Wapata2016-04-26

Secure? In what way?

iratozer (author)2016-02-01

If a person wanted to stay away from AC current altogether, could all 12 volt DC appliances from the RV industry be used?

WhyMeLord (author)iratozer2016-04-26

Yes but there are higher dc voltage units that work more efficiently. My RV I use an higher wattage inverter (input 48VDC 120 VAC) and 'time share' the load.

24 & 48 VDC systems are COTS (commercial of the shelf) available. 48 VDC may be more so as 48VDC is communications industry standard. 24 VDC is transpiration (trucks) industry standard.

ReyM9 (author)2016-04-01

sir i have a question how to check if the battery can charge by the solar panel?

WhyMeLord (author)ReyM92016-04-26

The charge controller is the key to that function. There is a tenancy to low ball the controller quality but that is false economy as a low quality controller can kill a battery in short order.

Standard auto batters will ok but deep cycle (think golf cart/RV batteries that can be found at most big box club stores) works best. (I don't regularly discharge below 50% unless it is an urgent need)

My system (runs the fridge, all my electronics, a hot plate and microwave by turns plus ceiling fans (Summer) and the HVAC heater fan motor (winter).

I'm working on a system (to be eventually posted here) that will run my pool pump as well.

A lot of useful information can be found on RV/news group and blogs.

ReyM9 (author)2016-04-01

sir i have a question how to check if the battery can charge by the solar panel?

fortney (author)2016-01-21

I thought that one had to put a higher voltage into a battery than the rated battery voltage to charge the battery.

I enjoy all of your instructibles and see each time that you are very knowledgeable and creative.


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Bio: I am an Electrical Engineer.I love to harvest Solar Energy and make things by recycling old stuffs. I believe ""IF YOU TRY YOU MIGHT ... More »
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