Sizing Solar Without Getting Sold the Wrong System
The most expensive solar mistake in Ghana is not paying too much — it is buying a system sized to a sales pitch instead of your actual home, then discovering it cannot carry your AC or dies halfway through dumsor. This guide shows you how sizing actually works, so you can hold a real conversation on the survey rather than take a number on trust.
The principle is simple: a solar system is sized to what you use and when you use it, not to your roof area or a round-number kVA. Everything below is how we turn your real usage into the right array, inverter, and battery.
Step 1 — Read Your ECG Bill
Your last three or four ECG bills are the single best evidence of what you actually consume. They show your monthly kWh, which tells us how much energy the system has to replace if it is to make a dent in the bill. A home billing 300 kWh a month needs a very different system from one billing 900 kWh.
What to Look For
- Monthly kWh — the headline consumption figure
- The trend — is it climbing as you add appliances or AC?
- Tariff band — higher bands make solar pay back faster because the units you offset are the expensive ones
Step 2 — List Your Real Loads
The bill tells us how much; your appliances tell us when and how heavy. We list what you run and for how long.
Light Loads (easy to carry)
Lights, phone chargers, Wi-Fi router, a TV, ceiling and standing fans — the small home essentials a 1.5kVA system covers.
Heavy Loads (size carefully)
- Air conditioning — the single heaviest household load. One split is manageable; multiple units running through the afternoon push you toward 5kVA and up.
- Fridges and freezers — modest running power but they cycle 24/7, so they shape the battery.
- Water pumps — short, sharp surges that the inverter must handle on start-up.
- Electric heaters and kettles — brief but very heavy; flag them so the inverter is not undersized.
This is why “what size solar do I need” has no phone answer — it depends on which of these you run and when.
Step 3 — Decide Grid-Tie, Hybrid or Off-Grid
The design decides what the system does for you as much as the size does.
| Design | What it does | Best for |
|---|---|---|
| Grid-tie | Cuts the daytime bill, switches off when the grid does | Stable supply, bill is the only goal |
| Hybrid | Cuts the bill AND rides out dumsor on battery | The popular Accra home choice |
| Off-grid | Full independence, no grid backstop | Sites with no reliable supply |
Most Accra homes choose hybrid because it does both jobs — read why in our solar installation overview.
Step 4 — Size the Battery for Dumsor
The array generates by day; the battery carries you when the sun is down or the grid is out. Size it to the loads you genuinely need overnight or through an outage — lights, fridge, fans, Wi-Fi, maybe one AC — not to every socket in the house, which inflates cost for no real benefit. Battery chemistry matters here: lithium goes deeper and lasts longer than tubular, which changes how much usable capacity you actually buy. See lithium vs tubular and Inverter & Battery Systems.
Step 5 — Add Headroom, Don’t Undersize
A system sized to the exact edge of today’s load has nothing left when you add a second AC or a new freezer next year. We size with sensible headroom so the system grows with you rather than choking — undersizing to hit a lower price is the false economy that leaves you short during the very dumsor you bought it for.
A Worked Feel for the Numbers
- Small home essentials (lights, fridge, fans, Wi-Fi) → around 1.5kVA, indicatively ₵18,000–25,000
- Mid-size home with some AC and a home office → around 3kVA, indicatively ₵35,000–50,000
- Larger home or small business carrying real AC load → around 5kVA, indicatively ₵55,000–85,000
These are indicative 2026 ranges (Optima), confirmed firm on a free survey — see the full Solar & AC Cost Guide.
Frequently Asked Questions
What size solar do I need for my home? It depends on your monthly ECG kWh and which heavy loads (especially AC) you run. We read your last few bills and list your loads to size it properly — there is no honest one-size answer down the phone.
Can a solar system run my AC? Yes, if it is sized for it. AC is the heaviest household load, so the array, inverter, and battery must be specced to carry it rather than bolted onto an undersized system.
How big a battery do I need for dumsor? Enough to carry the loads you genuinely need through an outage — lights, fridge, fans, Wi-Fi, maybe one AC — not the whole house. We size it to your real overnight need so you do not overpay.
Should I get grid-tie or hybrid? Hybrid if you want to ride out dumsor as well as cut the bill — the popular Accra choice. Grid-tie if your supply is stable and the bill is your only concern.
Get sized right the first time. Call +233 27 000 0866 — we read your ECG bills, list your loads, and design a system that carries them with headroom, confirmed on a free survey.