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.
Amongst the renewable energy sources of wind, solar and geothermal, Solar is increasingly becoming dominant. The main component of any solar energy installation are Solar PV panels. Although still relatively inefficient, the rise of Solar PV panels has been astronomical.
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. What is the average level of sunlight insolation in your location where the project is being planned?
7. How many days are you willing to stay off grid if you choose or if there is power outage. This is called days of autonomy – days the installation can run on your battery bank without shutting down.
Basic components of a Solar PV Installation in the Home
A basic Solar PV installation for the Home consist of the following components:
1. Solar PV panels
2. Solar Charge Controller
3. Battery Bank
4. Inverter to power your Alternating Current (AC) loadings
5. Appropriate wiring
6. Appropriate protection against lighting, short circuits, and overloads.
See : A Guide to Understanding Solar PV Panels Power System Installations
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?
ELECTRICAL LOAD 
QTY 
POWER RATING 
RUN HOURS 
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 
ELECTRICAL LOAD 
QTY 
RUNNING WATTS 
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 
ELECTRICAL LOAD 
RUNNING WATTS 
STARTING WATTS 
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 
ELECTRICAL LOAD 
QTY 
RUNNING WATTS 
RUN HOURS 
ENERGY (Wh) 
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 
SIZING OF NUMBER OF SOLAR PANELS REQUIRED 

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 