Key Takeaway
Net metering is usually the lower-cost starting point if your priority is reducing electricity bills and your grid supply is reliable. Battery storage adds evening solar use and, with the right equipment, brownout backup. The better choice depends on your export credit, nighttime consumption, installed battery cost, and need for reliable power. You can also combine both.
What is the difference between net metering and a solar battery?
Net metering is a billing arrangement. Surplus solar electricity goes to your distribution utility, which credits your bill. A battery is equipment that stores electricity at your property for later use.
| Question | Solar with net metering, without a battery | Solar with battery storage |
|---|---|---|
| Where does surplus solar go? | To the grid for bill credits | Into the battery; remaining surplus can be exported if approved |
| What supplies electricity at night? | The grid, with export credits reducing the bill | The battery, then the grid when needed |
| Does it provide brownout backup? | A standard grid-tie system does not | Yes, if designed and configured for backup |
| What additional costs apply? | Application, metering, and compliance costs as applicable | Battery, compatible equipment, installation, and eventual replacement |
Net-metering credits are a financial offset. They do not reserve electricity for your home during an outage.
Why is the export credit lower than the electricity rate?
Under Philippine net metering, export credits are based on the utility's blended generation cost, excluding other generation adjustments. The retail electricity price also includes transmission, distribution, and other charges. Exporting 1 kWh therefore generally does not pay for importing 1 kWh later.
Meralco's billing FAQ explains this distinction. Check your own utility's current export credit and the charges you actually avoid by buying fewer kWh. Fixed charges do not disappear simply because grid consumption falls.
For application steps, see our net-metering guide.
Which saves more? A simple peso example
Assume 10 kWh of surplus solar is available after daytime consumption. Use an illustrative avoided grid cost of ₱12/kWh, export credit of ₱8/kWh, and battery round-trip efficiency of 90%. These are calculation assumptions, not quoted current utility rates or guaranteed equipment performance.
| Option | Calculation | Daily bill benefit |
|---|---|---|
| Export the surplus | 10 kWh × ₱8 | ₱80 credit |
| Store and use it later | 10 kWh × 90% × ₱12 | ₱108 of avoided purchases |
| Battery advantage over exporting | ₱108 − ₱80 | ₱28 additional benefit |
The battery adds ₱28 per day in this example, or ₱840 across 30 identical days. This assumes sufficient usable storage and nighttime demand to consume all 9 kWh delivered, and that the alternative export credits would be used.
That additional benefit must recover the battery's installed cost and any extra inverter or electrical work. Allow for declining capacity, standby consumption, maintenance, financing, and replacement. Do not count the full ₱108 as additional savings over net metering.
A lower export credit or higher avoided grid cost improves storage economics. Limited surplus solar or low nighttime consumption weakens them. Commercial demand charges need a separate assessment.
When should you choose net metering, a battery, or both?
- Start with net metering when the grid is dependable, your budget is limited, and you regularly have surplus solar to export.
- Consider a battery when brownouts interrupt work or business, or when daytime surplus can cover substantial evening consumption.
- Combine both when you need backup and still expect surplus after charging the battery. An approved hybrid installation can store some energy and export the remainder.
For a resort or shop, backup may protect refrigeration, internet, lighting, or essential operations. Estimate avoided outage losses separately from electricity-bill savings. Keeping a battery reserve for emergencies also reduces the energy available for daily bill reduction.
What should you check before buying a battery?
Check usable capacity in kWh for runtime, and battery/inverter output in kW for appliances running together. Motor starting loads, backup circuits, compatibility, and warranty conditions also matter. A large battery cannot compensate for an undersized inverter.
Ask Onsolar to compare net metering alone with a battery option using your bills, daytime and nighttime consumption, essential backup loads, and local utility rates. The proposal should show additional battery savings and expected backup runtime separately.
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Get Free Solar QuoteCommon questions
Do I need a battery for net metering?
No. An approved grid-tie solar system can export surplus electricity without a battery.
Can I use net metering and battery storage together?
Yes, with compatible equipment and the required utility approval. The system can charge the battery and export remaining surplus.
Will net metering keep my lights on during a brownout?
No. Standard grid-tie systems shut down when the grid fails. Export credits do not provide backup power.
Will any solar battery provide backup?
No. The inverter, isolation equipment, wiring, and settings must support safe backup operation. Confirm which circuits will remain powered.
Does a battery always pay for itself?
No. Compare its total additional cost with savings after storage losses and forgone export credits. Backup convenience is a separate benefit.
Can I add a battery later?
Often, but it depends on your inverter and electrical design. Ask for a documented upgrade path and compatible battery models before purchasing.
Can a battery eliminate my electricity bill?
It may reduce grid consumption substantially, but weather, usage, battery capacity, and remaining utility charges affect the result. A zero bill is not guaranteed.
What if I cannot export excess solar?
A properly configured battery can capture surplus that would otherwise be curtailed. Use zero export income for that surplus in the comparison, while confirming utility requirements.