Application guide · Health facilities
Off-Grid Solar for Clinic: Vaccine Cold Chain Design
Off-grid solar for clinic buildings is designed around one load that cannot fail: the vaccine refrigerator. A health post that loses its cold chain for six hours destroys a month of vaccination coverage for the surrounding villages, and the fridge must hold 2–8 °C through a night, a cloudy day and a grid outage that may last a week. Everything else — lights, fans, a steriliser, a phone charger — is secondary to that one duty cycle.
Typical daily load
3.5–7 kWh
Array
1.5–6 kWp
Cold chain autonomy
48–72 h
This page covers the sizing method we use for rural clinics and health posts in Nigeria, Ghana and the Philippines: the load table including the fridge duty cycle, three plant tiers from a 1.5 kWp health post to a 6 kWp district clinic, indicative EXW cost bands, the WHO PQS and local regulatory requirements, and the installation details that keep a fridge cold in month thirty.
The cold chain is a duty cycle, not a wattage
A vaccine fridge is sold with a 60–80 W average draw, but that average hides the duty cycle: the compressor runs 40–60% of the time in a 32 °C room, and the pull-down after a door opening can be 300 W for twenty minutes. Sizing a clinic plant on the nameplate average is the single most common reason a fridge alarm fires at 03:00.
The second failure is temperature, not energy. A fridge rated for 43 °C ambient derates sharply at 45 °C, and a battery cabinet in the same room as the compressor works at 40 °C year-round. Both need shade and ventilation, and the battery needs to be outside the vaccine room so that a thermal event in one does not take out the other.
The third is the human one. A clinic that has never had reliable power has no culture of checking state of charge, and a system that silently switches to grid or generator when the battery is low masks a failing array for months. Remote monitoring with a monthly report to the district health office is part of the design, not an optional extra.
- ✓Fridge sized on nameplate average instead of duty cycle and pull-down
- ✓Battery cabinet in the same hot room as the compressor
- ✓No low-SOC alarm, so a failing string is discovered when vaccines spoil
- ✓Steriliser and autoclave treated as a continuous load instead of a 1–2 hour step
- ✓Array installed on an asbestos roof that cannot take wind or point load
Typical clinic load values
The table is a 4-room health post with a vaccine fridge, a small steriliser and a delivery room. District clinics add a cold room, a laboratory fridge and air-conditioning, which roughly doubles the daily kWh.
| Item | Power | Hours | Daily energy |
|---|---|---|---|
| Vaccine fridge, 60 W avg (40–60% duty) | 60 W | 24 h | 1.44 kWh |
| LED lighting, 12 points | 90 W | 6 h | 0.54 kWh |
| Ceiling fans, 4 rooms | 240 W | 8 h | 1.92 kWh |
| Steriliser, 1.2 kW (1 h cycle) | 1,200 W | 1 h | 1.20 kWh |
| Laptop, radio, phone charging, pump | 180 W | 7 h | 1.26 kWh |
Reference health post: 6.4 kWh a day, with a 2.5 kW peak when the steriliser and the fridge compressor start together. The peak sets the inverter; the fridge duty cycle sets the battery, because the fridge must run through the night regardless of what else is switched off.
Recommended configurations
Cold-chain autonomy is the design constraint: the battery must carry the fridge for 48–72 hours without sun. That is roughly 3 kWh of usable storage per fridge, plus the night load of the building. All three tiers include a changeover to grid or generator where one exists.
| Tier | PV array | Battery | Power electronics | Serves |
|---|---|---|---|---|
| H1 — health post, 1 fridge | 1.8 kWp (8 × 230 W) | 25.6 V 314 Ah (8.04 kWh) | 3 kVA hybrid, 230 V single-phase | 3.5 kWh/day, 48 h cold chain |
| H2 — clinic, 2 fridges + lab | 3.2 kWp (14 × 230 W) | 51.2 V 200 Ah (10.24 kWh) | 5 kVA hybrid, 230 V single-phase | 6.4 kWh/day, 60 h cold chain |
| H3 — district clinic, cold room | 6.5 kWp (29 × 230 W) | 2 × 51.2 V 200 Ah (20.48 kWh) | 10 kVA hybrid, 3-phase ready | 14 kWh/day, 72 h cold chain |
Do not put the fridge on the same circuit as the steriliser. A 1.2 kW steriliser starting while the compressor is in pull-down is a 3.7 kW step that trips a 3 kVA inverter; separate circuits plus a 30-second start delay cost almost nothing.
Indicative cost ranges (USD, EXW Ningbo)
Bands cover modules, mounting, hybrid inverter, LFP storage and the DC/AC distribution board. The vaccine fridge itself, civil works, freight and installation are excluded; WHO PQS fridges are usually procured separately by the health ministry.
| Item | Specification | Indicative range |
|---|---|---|
| H1 kit — health post | 1.8 kWp · 8.04 kWh LFP · 3 kVA hybrid | USD 2,900 – 3,700 |
| H2 kit — clinic | 3.2 kWp · 10.24 kWh LFP · 5 kVA hybrid | USD 4,600 – 5,800 |
| H3 kit — district clinic | 6.5 kWp · 20.48 kWh LFP · 10 kVA hybrid | USD 9,400 – 11,800 |
| Remote monitoring + SIM | 4G gateway, temp + SOC alarms, 12 months data | USD 180 – 320 |
| Fridge temperature logger | 2 × PT100, 5-year battery, USB export | USD 90 – 150 |
- Indicative EXW ranges for the power plant only. Final pricing depends on storage tier, inverter brand and port; a formal quotation follows a load and fridge audit.
- Cold-chain fridges (WHO PQS E003) are procured separately at USD 1,200–3,500 each; the solar plant above is sized to run them, not to include them.
- Remote monitoring is not optional on a clinic: without it, a failed string is discovered when vaccines are discarded, which costs more than the whole solar plant.
All prices on this page are indicative EXW ranges compiled from current container quotations. They are not a binding offer: freight, duties, installation and exchange rates move, and the final price is issued after we receive your load list and delivery port.
Local adaptation: voltage, climate and certification
Health facilities are procured through ministries and donors, so the equipment list has to satisfy both the local electrical code and the cold-chain specification. These are the differences that matter in our four main markets.
| Market | Grid & code | Climate | Certification |
|---|---|---|---|
| Nigeria | 230 V / 50 Hz; NEMSA inspection, NPHCDA solar-for-health spec | 35–40 °C, harmattan dust, unreliable grid (4–12 h/day) | SONCAP, WHO PQS for fridges, NEMSA for the installation |
| Ghana | 230 V / 50 Hz; Energy Commission, Ghana Health Service spec | 30–34 °C, high humidity, 1,800 mm rain | EC registration, WHO PQS, GS cables |
| South Africa | 230 V / 50 Hz; SANS 10142-1, load shedding stages 1–6 | −5 to 38 °C, hail, coastal salt | SANS 10142-1 CoC, SANS 60598 luminaires |
| Philippines | 220 V / 60 Hz; 60 Hz fridge and inverter required | Typhoon zone, 2,000 mm rain, 33 °C and 85% RH | DOE compliance, FDA cold-chain rules, NTC not applicable |
Installation points that protect the cold chain
Audit the fridge, not the building
Log the fridge compressor current for 72 hours: duty cycle, pull-down peak and night ambient. The fridge is 20–40% of clinic energy and 100% of the risk; the rest of the load can be managed.
Give the fridge its own circuit and its own battery priority
Wire the fridge to a dedicated output that the inverter never sheds. Lights and fans can be load-shed at 30% SOC; the fridge must run to 10%.
Keep the battery out of the vaccine room
Ventilated, shaded, on a plinth, with 1 m clearance. A 40 °C battery room halves LFP life, and a thermal event in the battery must never threaten the vaccines.
Shade the fridge and ventilate its condenser
A fridge in direct sun at 38 °C ambient runs a 70% duty cycle instead of 45%. A simple roof overhang and 100 mm of rear clearance cuts daily energy by 0.4–0.6 kWh — more than an extra panel costs.
Set alarms that reach a person
Temperature above 8 °C for 30 minutes, SOC below 30%, array yield below 60% of expectation for two days. Send them by SMS to the clinic nurse and the district cold-chain officer, not to a dashboard nobody opens.
Commission with a 48-hour fridge test
Run the fridge on battery alone from a full charge and log the temperature. A plant that cannot hold 2–8 °C for 48 hours has not met the specification, whatever the voltage readings say.
Hardware for this scenario
Storage and modules for clinic plants. Send the fridge model, its daily duty cycle and the building load list, and we will return a plant sized to the cold chain first and the building second.
DLXN-F5200 51.2 V 200 Ah
10.24 kWh at 51.2 V is the core of a clinic plant: it carries a vaccine fridge, lights and a steriliser through two cloudy days with 20% reserve left.
View specifications →
DLXN-F2314 25.6 V 314 Ah
8 kWh at 25.6 V for health posts running a single fridge and lights, where a 51.2 V rack is more capacity than the building can use.
View specifications →
DLXN-M10-230W module
Thirteen modules give the 3 kWp array for a clinic roof; the 18 V/230 W format keeps the string inside a 150 V MPPT window even at 45 °C cell temperature.
View specifications →
DLXN-M10-200W module
For smaller 1.5–2 kWp health-post arrays, and for ground mounts where the roof is asbestos or thatch and cannot take load.
View specifications →
Market pages and next steps
Frequently asked questions
How much does off grid solar for a clinic cost?
A 4-room health post with one vaccine fridge needs about 1.8 kWp and 8 kWh, which is USD 2,900–3,700 EXW. A clinic with two fridges and a laboratory is USD 4,600–5,800, and a district clinic with a cold room USD 9,400–11,800. Freight, installation and the fridges themselves are separate.
How long can the vaccine fridge run without sun?
Design for 48 hours minimum and 72 hours at district level. A WHO PQS fridge drawing 60 W average needs about 1.5 kWh a day, so 48 hours is roughly 3 kWh of usable storage plus the building night load. With a 10.24 kWh LFP pack and 80% usable depth of discharge, a clinic holds 60–65 hours.
Do I need a special inverter for a vaccine fridge?
You need a hybrid inverter with a dedicated non-shedding output and a surge rating of at least 3× the compressor locked-rotor current — typically 5 kVA for a 3 kVA continuous load. A cheap inverter that trips on compressor start is the most common cause of cold-chain failure in solarised clinics.
Can the clinic stay connected to the grid?
Yes, and it should where the grid exists. Set the hybrid to solar-first, battery-second, grid-third, with the fridge on the priority output. During load shedding the plant islands automatically; when the grid returns it recharges the battery and stops cycling it, which extends pack life.
What maintenance does a clinic solar plant need?
Quarterly: wash the array, check the fridge door seals and condenser, read the battery SOC log. Annually: torque DC terminations, test the changeover, verify the temperature logger calibration. Budget USD 120–200 a year and put it in the district maintenance contract, or the plant will be at 60% of its designed output by year three.
Send the fridge and load list
Tell us the fridge model, the number of rooms, whether the grid reaches the site, and the nearest port. We will return a plant sized to 48–72 hours of cold chain and an EXW price within two working days.
- Email:
- dlxn@dlxnsolar.com
- Delivery ports:
- Durban · Lagos · Tema · Manila
- Basis:
- EXW Ningbo / CIF
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