Off-grid communities vary in size, location and energy-demand, so choosing the right technology is key to ensuring long-term project success.
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- Solar home systems (SHS), and
- Mini-grids
We present a third contender:
- Mesh-grids
SHS: Flexible & fast, but insufficient power
SHS are flexible, fast and simple. They have provided millions with basic access to electricity for essentials like lighting and phone charging. However they simply don’t provide enough energy or power for productive use – which is key for long term sustainability of last-mile electrification projects.
Although impactful, SHS are an incomplete solution, incomparable to grid-like solutions (mini-grids and mesh-grids) in terms of providing productive power for developing communities.
Mini-grids: High power, but expensive & rigid
Mini-grids are built with a centralised architecture where energy is generated and stored at a single point then distributed all the way to the farthest households. Mini-grids supply high levels of productive power which makes them suitable for densely populated areas that lack a reliable grid. However approximately 65% of unenergized people (500 million globally) reside in rural villages with dispersed households, low population density, and variable energy demands tied to the seasonal changes of subsistence farming. By the nature of their design, mini-grids are not engineered to effectively service this market.
The main drawback of deploying mini-grids at the last-mile comes from the high-cost of distribution assets (poles, cables, inverters). Safely distributing power over long distances, whilst also accounting for peak utilization, necessitates high-voltage and high-current cabling, heavy duty transmission poles and large inverters – all of which can only be serviced by licensed technicians who need to travel far and wide to reach the site. In the event of failures, it’s expensive and slow to perform maintenance and the quality of service suffers.
As a result, approximately 50% of capital expenses goes into distribution infrastructure whilst operational expenses can amount up to 40%* of total project costs. This is why mini-grids have an average payback period of 10 to 20 years, many failing to demonstrate financial viability when deployed in last-mile regions.
The centralized architecture of mini-grids does not efficiently service dispersed populations
The World Bank estimates that annual mini-grid installations need to increase by 40x to meet 2030 electrification goals, but their high capital and operational costs are prohibiting them from scaling as a sustainable last-mile electrification solution.
Mesh-grids: Powerful, modular & scalable
Okra mesh-grids (OMGS) hybridize the speed and flexibility of SHS with the reliability and energy availability of mini-grids.
In contrast to centralized mini-grids, mesh-grids are decentralized and modular –Â generation and storage assets (solar panels and batteries), along with inverters, are installed at individual households.
This design ensures the majority of energy is generated and consumed at the same place (just like SHS), but additionally, neighbouring households can also interconnect and form power-sharing clusters, where smart algorithms redistribute excess power at 50V DC, which can be operated on safely by local community members who have basic training.
This power-sharing feature of mesh-grids supports load variability, increases reliability, and reduces upfront costs. Meanwhile, isolated households can remain standalone until there is a neighbouring household that’s ready to connect and share power. Mesh-grids expand freely over time as more households join a network and demand grows.
This decentralized architecture is fundamentally enabled and controlled by the Pod – Okra’s proprietary controller that simultaneously manages power distribution, remote monitoring, and mobile billing. Each Pod outputs 1.2kW (AC or DC) – enough to power productive appliances and drive network profitability. Excess power from commercial loads or nearby grids can be drawn into mesh-grids for lower cost distribution via Okra’s “Grid Gateway” (more on this to come soon).
A primary advantage of decentralizing generation and storage is that it significantly reduces the total amount of power moving throughout a network, as energy is mostly generated and consumed by the same household and any excess is optimally sent to nearby homes. This node-to-node distribution in mesh-grids requires 10x thinner cables, reducing distribution costs by 90% compared to centralised mini-grids.
Centralized mini-grids
- 10× thicker conductors needed to disribute high voltage (230V to 33kV) and high current
- Isolated households have a significantly higher cost per connection, or are left unconnected
- High power output, support commercial/industrial anchor loads
Decentralized mesh-grids
- Isolated households can be connected as standalone systems initially, then inter-connect into mesh-grid clusters later (once a neighbouring household is also ready to inter-connect)
- Housholds >50m apart do not need to be connected, reducing cabling needs
- Algorithms optimize power transfer to reduce waste
Centralized mini-grids
- Rigid, cannot be scaled incrementally
Battery capacity cannot be increased without being replaced, adding significant costs to replace and upsize all assets when demand grows.
Decentralized mesh-grids
- Modular, assets can be added over time
Extra solar panels and batteries can be added to individual households to match load growth or staggered sign-ups, without replacing existing assets or massively oversizing.
Centralized mini-grids
- Unsafe, for local community members to maintain
- Technicians must travel to the last-mile to resolve issues
- Majority of lifetime O&M costs is for staff & logistics.
- Centralized asset failures bring the entire grid down
- Simple to locate problems with fewer points of failureÂ
Decentralized mesh-grids
- Maintainable by local staff and issues can be resolved immediately
- Builds community trust and empowerment
- Reduces staff and logistics costs by ~50%
- Issues occur on individual homes, isolating outagesÂ
- Distributed assets results in distributed issues across site
Centralized mini-grids
- Requires land acquisition
Land acquisition requires village-wide consensus, which takes >6 months on average. Once land is purchased, security needs to be paid for.
Decentralized mesh-grids
- Don’t require land
Developers only need direct agreement from the household to install equipment.
Cost Comparisons
When it comes down to it, mesh-grids provide more utility per dollar for off-grid energy developers because the technology is specifically tailored to the unique traits of last-mile communities.
The comparison below is an apples-to-apples summary comparison between a mini-grid and mesh-grid, which are both specced to provide an average daily load of 600Wh/day, with Lithium LFP batteries, in a rural off-grid communitiy.
Mini-grids
Mesh-grids
Power output
>1.2kW AC
1.2kW AC & DC
Distribution specs
230V AC (single or 3-phase)
50V DC
National grid connect
Draw & supply
Draw only
$ per connection
~$1100
~$625
(~$350 with REA Nigeria subsidy)
CapEx for 10k households
$11M
$6.25M
 Simulations
To further validate this mini vs. mesh-grid cost comparison, this example from Okra’s Network Planner tool uses satellite data to detect households, automatically plan mesh and mini-grid networks, and produce a detailed cost comparison. Across various villages, we see variation in where mesh vs. mini grids are favorable, and the benefit of this analysis is to determine where each technology is most suited to provide the lowest cost electrification. The following example demonstrates a mesh-grid suited community in Haiti.
An example site simulation of a last-mile community in Haiti, from Okra’s Network Planner tool
Number of households = 2,636
Designed daily load = 400 Wh/day
Totals
Mini-grids
Mesh-grids
PV capacity
390 kWp
392 kWp
PV cost
$136,500
$137,400
Battery capacity
2,320 kWh
Battery cost
Inverter cost
$261,400
$197,700
Distribution cost
(cables, poles)
BOS & mounting cost
$225,300
Metering cost
$329,500
CapEx
$2,693,600
$1,649,700
$ per connection
$625
We generate these simulations using averages from Okra project data, as well as research and other field data. Our models are continuously updated to give an accurate forecast, but we’re always eager to hear feedback or adjust assumptions based on other suppliers. Stay tuned for a much deeper dive into these simulations and the assumptions they’re built on, coming soon!
Advancements in battery and solar technologies make decentralized infrastructure affordable and practical. With mesh-grid technology we can leverage these benefits to provide robust and reliable electrification at the lowest cost.Â
Mesh-grids are already being rolled out around the world, with particularly exciting scale-ups happening in Nigeria as we speak! Let us know if you’re an energy developer or otherwise interested in seeing mesh-grids help end energy poverty.
It’s time to bring #Powe​​rToThePeople
