What Size Off Grid Solar System Do I Need?

12v, 24v, or 48v? Which is best? – As you’re shopping you’ll come to learn that panels and inverters typically come in either 12, 24, or 48 volt options. Most RV’s and boats typically use 12V battery banks, so people usually stick with 12V panels.12 volt systems used to be the standard for homes, but today, many larger home systems are rated at 24v or 48v.12v systems are good for many DIY solar scenarios, such as RVs/motorhomes/vans, camper trailers, and small cabins or tiny homes.

How big off grid system do I need?

How many solar panels do I need to go off-grid? – The number of solar panels needed to go off-grid, solely depends on the following factors:

Amount of electricity you use Amount of useable roof space Amount of direct daily sunlight The type of solar panel you choose

The average off-grid home usually requires about 7 Kw (or 7000 Watts) of power to rely entirely on its own energy production. Solar panels come in various forms, shapes and sizes. Two major factors that determine the amount of solar panels you will need to go off-grid, depends on your energy requirements and the performance output of each panel.

Panel performance is rated under standard testing conditions (STC): irradiance of 1,000 W/m 2, solar spectrum of AM 1.5 and module temperature at 25 °C.

Usually the larger the panel, the higher the panel performance. For example, a 100-watt solar panel typically measures 47 x 21,3 x 1,4 inches. A 200-Watt solar panel measures 64 x 26 x 1,4 inches (these are rough estimates). The bigger the framework, the more photo-voltaic cells are able to be mounted inside of it, thus more performance.

If your energy requirements were as such as the average mentioned above (7 Kw) and you were to use 200-watt solar panels, then you’d need more or less 35 panels to take your home off-grid. Or if you used 350-watt solar panels, you’d need 20 panels. To give you an idea of how much area say 35 solar panels will take up, you will need to find the total square footage.

In the U.S, the average homes roof is about 1700 square feet,

35 solar panels will take up more or less 389 square feet of your homes roof space. This leaves more than enough room in case you add any extra panels to your system in the future.

To make things easier for you, we have compiled this chart to give you a basic ballpark on how many solar panels you will need depending on your situation.

Average Monthly Electric Bill Solar System Size Number of Panels (Based on 200W Panels) Estimated Space Needed
$60 5 kW 26 panels 289 sq. ft
$120 10 kW 52 panels 578 sq. ft
$240 20 kW 105 panels 1,168 sq. ft
$600 50 kW 255 panels 2,838 sq. ft
$1,200 100 kW 510 panels 5,676 sq. ft
$2,400 200 kW 1020 panels 11,352 sq. ft

A 200 Watt solar panel measures roughly 11,13 sq. ft)

How do I calculate what size solar system I need?

What affects solar panel output efficiency? – Here’s where solar panel quality makes a difference. Not all solar panels are alike. Photovoltaic (PV) solar panels (most commonly used in residential installations) come in wattages ranging from about 150 watts to 370 watts per panel, depending on the panel size and efficiency (how well a panel is able to convert sunlight into energy), and on the cell technology.

  1. For example, solar cells with no grid lines on the front (like SunPower ® Maxeon ® cells) absorb more sunlight than conventional cells and do not suffer from issues such as delamination (peeling).
  2. The construction of our cells makes them stronger and more resistant to cracking or corrosion.
  3. And a microinverter on each panel can optimize power conversion at the source, in contrast to one large inverter mounted on the side of the house.
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Because of these wide variations in quality and efficiency, it’s difficult to generalize about which solar panels are right for you or how many you’ll need for your home. The main takeaway is that the more efficient the panels are, the more wattage they can produce, and the fewer you will need on your roof to get the same energy output.

  1. Conventional solar panels usually produce about 250 watts per panel, with varying levels of efficiency.
  2. In contrast, SunPower panels are known to be the most efficient solar panels on the market.
  3. To figure out how many solar panels you need, divide your home’s hourly wattage requirement (see question No.3) by the solar panels’ wattage to calculate the total number of panels you need.

So the average U.S. home in Dallas, Texas, would need about 25 conventional (250 W) solar panels or 17 SunPower (370 W) panels.

What can I run on a 5kW solar system?

5kw solar systems have been installed by many households in Australia. They produce sufficient power to run an ordinary home as efficiently as when using grid electricity. You can run a washing machine, air conditioner, fridge, water heater, oven, and TV with a 5kw solar system.

How do you calculate off grid?

Building Your Off-Grid Solar System You can calculate your daily electricity usage in Watt-hours by identifying the wattage ratings of the appliances and how many hours you intend to run them each day. For example, a single 50 Watt fan operating for 3 hours per day will result in 150 Wh per day (50W x 3 hours = 150Wh).

How much solar and battery do I need to go off-grid?

Key takeaways – Considering that the average solar battery is roughly 10 kilowatt-hours (kWh) in size :

If you want to save the most money possible, you’ll need enough battery storage to cover your energy usage when your solar panels aren’t producing – somewhere around 2-3 batteries If you want to keep the power on when the grid is down, you’ll usually just need one solar battery If you want to go off-grid completely, you’ll need far more storage capacity, more along the lines of 8-12 batteries

Whatever your motivation for adding solar and storage to your property, you can sign up on the EnergySage Marketplace to get started comparing solar-plus-storage quotes for free.

What size solar system does the average house need?

How Many Solar Panels to Power a House? – When estimating how many kilowatts of solar do I need, it’s important to consider the size of your home. A home size of 1500 sqft would consume an avg. of 633 kWh/month, on the other hand, a 3000 sqft home would consume an avg. What Size Off Grid Solar System Do I Need How many solar panels do I need for a specifically sized solar system? To determine the number of panels you need to achieve a given solar system size, divide it by the wattage of each panel (which averages around 320 watts). For example, if you’re aiming for a 4 kW system, you’ll divide 4 kW (or 4,000 watts) by 320 watts to get 12.5.

  • Round up the answer to 13, which is the number of panels you need.
  • How many solar panels do I need for common appliances? You can also determine the number of panels you need on a per appliance basis.
  • This approach is helpful if you want to add panels because of increased usage or when buying a new appliance.

To calculate this, divide the average annual wattage of the appliance by the panel wattage. For example, a 600 kWh refrigerator would need two solar panels (600 / 320)

How many solar panels does it take to charge a 5kW battery?

How many solar panels will you need for 5kW? – To make up a 5kW solar system, you need 14 solar panels, assuming you use 370W panels – that will actually give you 5.18kW. Each panel will be about 1.8 metres x 1 metre, so you’ll need at least 25.2m² of roof space. To give you a feel for how big 25.2m² is, this picture may help:

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How many solar panels do I need for a 5kW battery?

How many panels & how much roof space for a 5kW solar system? – A modern-day 5kW solar system will be comprised of between about 15-20 panels and will require about 25-35 m 2 of roof space, depending on the wattage of the panels and how they’re tilted.

How do you calculate load for off-grid solar panels?

How to Size an Off Grid Solar PV System for the Home What is currently happening in our world With the planet continuing to warm up and the increased pressure on humanity to ditch fossil fuels and embrace other forms of energy that don’t harm the planet, renewable energy has seen a steady rise in its popularity and usage.

  • Solar PV installation in the rooftop of houses are increasingly becoming popular as we race to reduce our carbon footprint and keep the planet safer.
  • Basic Things to know Before you Start Your Solar PV Sizing Project in the Home
  • To successfully implement an off grid solar PV installation in the roof top of your house, there are some basic things you need to be aware of before you embark on this journey:

1. What is your load requirement? 2. Do you want to power all your loads when off grid ? Or 3. Do you want to power some loads and leave some on grid? 4. What is your budget for this project? 5. Can your budget finance a project where all your loads requirements can be taken off grid and powered by the Solar PV installation? 6.

  1. Basic components of a Solar PV Installation in the Home
  2. A basic Solar PV installation for the Home consist of the following components:
  3. 1. Solar PV panels
  4. 2. Solar Charge Controller
  5. 3. Battery Bank
  6. 4. Inverter to power your Alternating Current (AC) loadings
  7. 5. Appropriate wiring

6. Appropriate protection against lighting, short circuits, and overloads.

  • See :
  • Sizing Procedure for Solar PV Installation for Your Home
  • To correctly size your Solar PV Installation for Your Home, follow the following basic steps:
  • 1. Determine the loads that are to be put off grid or during power outage
  • 2. Calculate the running watts of all the loads
  • 3. Calculate the starting watts (also known as surge watts) of all the loads
  • 4. Determine the total load in watts by adding total running watts to the highest starting watts of the load to be powered by the Solar PV installation

5. Determine the KVA rating of your Inverter by dividing by 0.8, the nominal power factor.6. Determine the size of your battery bank to enable you stay off grid for the days of autonomy you desire or when there is power outage for that long.7. Determine the size of your Solar PV array that will power your load during hours of sunlight as well as charge the battery bank at the same time.8.

Determine the size of your charge controller. Sample Sizing Calculation of Solar PV Installation for the Home Suppose I stay in a region with a maximum of 5 hours sunlight and want to install an off grid solar PV installation that can power my total loads shown below for two days continuously according to the allotted run hours without utility power.

How many solar panels and batteries do I require? What size of Solar Charge controller is needed?

Deep Freezer 2 115W 12
Submersible pump (1Hp) 1 750W 0.5
TV 2 100W 12
Lighting Loads Lot 200W 12
Juicer 1 400W 0.5

Steps 1 & 2 As per step 1, all loads are to be put on the solar PV installation. The running watts have been given for each electrical loads, however total running watts for each electrical load is:

Total Deep Freezer Load 2 2*115 = 230W
Total Submersible pump Load 1 1*750 = 750W
Total TVs Load 2 2*100 = 200W
Total Lighting Loads Lot = 200W
Juicer 1 1*400 = 400W
Total = 1,780W
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  • Note that the running watts of an appliance can either be gotten from the name plate label of the device or you can simply multiply the rated current and voltage of the device on the name plate label if given by using the following relationships:
  • Power in VA (volt amps) = Rated current x Rated Voltage
  • Power in Watts = Power in VA x Power factor.
  • To simply our calculations, we assume power factor = 1
  • Step 3: Calculate the Starting Watts of all the Electrical loads

    Total Deep Freezer Loads 230W 2*230 = 460W
    Total Submersible pump Load 750W 3*750 = 2,250W
    Total TVs Load 200W 0
    Total Lighting Loads 200W 0
    Juicer 400W 2*400 =800W
    Total 1,780W 3,510W


  • Step 4: Calculate Total Loads in Watts Required.
  • Total Load in Watts = Highest Starting Watts plus Total running Watts = 2,250W + 1,780W = 4,030W = 4.03KW (1KW = 1,000W)
  • Step 5: Determine KVA Rating of Inverter
  • KVA Rating of Inverter = Total Load in Watts/0.8 (Power Factor = 0.8) = 4.03KW/0.8 = 5.0375KVA A standard size of 5KVA inverter will be able to sufficiently power the loads. Step 6: Determine Battery Bank Size for Days of Autonomy Here we want to be able to power all our loads for two days without power.

    Total Deep Freezer Load 2 230W 12 230*12 = 2,760
    Total Submersible pump Load 1 750W 0.5 750*0.5 = 375
    Total TVs Load 2 200W 12 200*12 = 2,400
    Total Lighting Loads Lot 200W 12 200*12 = 2,400
    Juicer 1 400W 0.5 400*0.5 = 200
    Total 1,780W 8,135Wh


  • Total Energy consumed for 1 day based on the allotted run hours by all electrical loads is = 8,135Wh
  • Using a 12Volts battery system, total battery Ah required daily = Total Energy (Wh) for 1 day /12 = 8,135/12 = 677.92Ah
  • Battery Ah needed = ( Daily Ah consumption * Days of Autonomy *load expansion
  • factor)/DOD (%)
  • Daily Ah consumption = 677.92Ah
  • Days of Autonomy = 2 days
  • Load Expansion factor = 1.20 (We are assuming a load expansion factor of 20%)
  • DOD (Depth of Discharge) = 0.5 (We are using Lead acid batteries with DOD = 50%, for AGM batteries, it is 80% )
  • Battery Ah needed = (677.92 x 2 x 1.20)/0.5 = 3,254.016Ah Using a standard 500Ah battery, we arrive at total number of batteries required = Total Ah/500 = 3,254.016/500 = 6.5 batteries. Therefore, approximately 7Nos, 500Ah batteries connected in series are required to power the electrical loads for the allotted time for two days off grid.

    Size of Solar Panels required to supply load and charge batteries Wp = (Wh of Power Required by Load * 1.3)/Maximum hours of Sunlight
    Wh of load of batteries = 3,254.016 x 12 = 39,048.192Wh
    Wh load of connected loads = 8,135Wh
    Power loss factor correction for Solar Panels 1.3
    Maximum hours of Sunlight in your location 5
    Wp of Solar panel required = (39,048.192+8,135) *1.3/5 = 12,267.63Wp
    Chosen Solar panel rating 400W
    No. of Solar Panels Required 12,267.63/400 = 30.67

    For this project, approximately 31Nos**, 400W Solar panels will be required to successfully power the loads and charge the batteries during off grid time in the day with sun light hours and also be able to power the loads during nighttime. Step 8: Determine Size of Charge Controller There will be Seven (7) Nos, 500Ah batteries in series giving us a total = 12V X 7 = 84V DC Assuming we are using the LG LG400N2W-A5 (400W) Solar Panel, the maximum power voltage is 40.8V and its current is 9.81 Amps,

    To sufficiently charge the batteries, voltage applied to the batteries must be greater than 84V DC, Three (3) Solar panels in series will provide = 40.8 x 3 = 122.4V to charge the batteries. Therefore, number of parallel strings of 3Nos solar panels in series will be = 31/3 = 10.33 = 11 approx Total Current produced by 11Nos parallel strings of 3Nos solar panels in series = 11 x 9.81 = 107.91 Amps.

    Therefore, a charge controller of at least 120 – 150 Amps will suffice. **Note that we calculated approximately 31Nos solar panels required. But for actual implementation, we shall require 33Nos solar panels. : How to Size an Off Grid Solar PV System for the Home