Solar Off-Grid Energy Solutions: A Guide to Components, Benefits, and Costs
Introduction
Electricity is a critical component of modern society as it powers everything from homes, farms, cars, industries, etc. Sources of electricity in Kenya: Hydro-electric, geo-thermal, thermal, wind and solar. Access to electricity here in Kenya is majorly by:
- Connectivity to the grid- KPLC
- Off-grid PV system- Solar
How off-grid PV systems work
Solar energy is harvested using photovoltaic (PV) modules, commonly referred to as solar panels, during the period when sunlight is available. This energy is used to power the loads and also to charge the batteries. The energy is stored in the batteries during peak “sun-hours” will be used to meet the load requirement when sunlight will not be available i.e. at night.
The major system components are:
- PV modules (solar panels)
- Inverter charger
- Battery Energy Storage System
- Balance of system components
PV Modules
This is the component of a solar system that outputs DC electricity as a result of exposure to sunlight. The number of modules is determined by a combination of factors including: energy needs, availability of space, geographical location, etc.
Inverter charger
This component pulls DC output power from the solar panels and converts it to AC to enable utilization by the home appliances. The inverter is sized according to the following factors: load requirements, PV output, geographical location, future expansion, etc.
Battery Energy Storage Systems (BESS)
This is a type of energy storage system that uses batteries to store electrical energy from sources such as solar or wind power. The stored energy is used to meet the load demand for the period when sunlight is not available. The battery technologies in the Kenyan market currently are:
- Super-capacitor based energy storage
- Lithium ion battery
- Lead acid battery
Comparison between lithium-ion battery and lead-acid battery
Assumptions
- Energy requirement- 5kWh
Properties of Lithium ion vs Lead acid battery
| S.No | Item Description | Super-capacitor | Lithium Ion | Lead Acid |
|---|---|---|---|---|
| (i) | Depth of discharge (DoD) | 100% | 100% | 50% |
| (ii) | Lifespan | More than 35 yrs | More than 15 yrs | Between 2 to 3 years |
Battery size comparison (considering the respective permissible DoD as shown above)
| S.No | Energy requirement | Super-capacitor | Lithium Ion | Lead Acid |
|---|---|---|---|---|
| (i) | 5kWh | 5kWh | 5kWh | 10kWh |
Price comparison, per kWh
| S.No | Item Description | Super-capacitor | Lithium Ion | Lead Acid |
|---|---|---|---|---|
| (i) | Approximate price per kWh (KES) | 97,000 | 60,000 | 16,500 |
Total cost of ownership comparison – over 15 year period
Calculations are based on the price comparison in the table above
| Battery type | Battery size required (kWh) | Approximate price per kWh | Total price | Battery lifespan (Y) | Desired battery lifespan | Number of replacements | Total cost of ownership during 15 year period |
|---|---|---|---|---|---|---|---|
| Lead acid | 10 | 16,500 | 165,000 | 3 | 15 | 4 | 825,000 |
| Lithium ion | 5 | 60,000 | 300,000 | 15 | 15 | 0 | 300,000 |
| Super-capacitor | 5 | 97,000 | 485,000 | 35 | 15 | 0 | 485,000 |
Conclusion
- Lithium ion batteries are cheaper in the long term
- Lead acid batteries are 2.75 times more expensive than Lithium ion batteries
Brian Sambu is a highly skilled Electrical Engineer and Solar Expert certified by the Energy and Petroleum Regulatory Authority of Kenya. With a strong background in electrical installation, project management, and sales engineering, Brian brings a wealth of knowledge and expertise to any team. His experience includes working on various engineering projects, specializing in renewable energy solutions. Brian's commitment to excellence and his passion for sustainable energy make him a valuable asset in the field.
