Solarman PHBatteries get a lot of attention in solar marketing. They are also the part that most changes the price of a system. In our own planning bands, a 5 kW hybrid system starts at ₱318,000, compared with ₱235,000 for a 5 kW grid-tie system. That difference should buy you something you actually need.
Here is how we think about whether a battery is worth it for a particular home or business.
What a battery does, and does not do
A plain grid-tie system shuts down when the grid goes down. This is a safety requirement called anti-islanding: it stops your panels from feeding power into lines that workers may be repairing. So during a brownout, a grid-tie system gives you nothing, even on a sunny day.
A hybrid system adds a battery and a hybrid inverter. When the grid fails, it can keep selected circuits running from the battery and the panels. When the grid is up, it can store daytime solar and release it in the evening instead of exporting it at the lower net-metering credit rate.
What a typical home battery does not do is run the whole house, including every air conditioner, through the night. Batteries are sized for the loads that matter most, and the backup circuit is wired for exactly those loads.
When a battery is usually worth it
- Outages cost you something real. Spoiled stock in a shop chiller, lost work hours, a medical device, a water pump, or simply a household that cannot cope with frequent brownouts.
- Much of your use is in the evening. If the house is empty during the day and busy at night, storing solar for later lets you use more of it yourself.
- You would rather store than export. Because exported power earns less than you pay for imported power, storing it for the evening can make sense, as long as the battery cost is justified.
When it usually is not
- Outages are rare or short where you are, and your main goal is a lower bill.
- You use most of your power in the daytime. Working from home with aircon running in the afternoon is a good match for grid-tie solar alone.
- Your budget only fits a battery by shrinking the panel array. A smaller array with a battery can save less than a properly sized grid-tie system.
If you do want one, size it honestly
Two numbers matter. The first is the battery’s usable capacity in kilowatt-hours: how much energy it can actually deliver. The second is the inverter’s power rating in kilowatts: how much load it can run at once. A large battery behind a small inverter still cannot start several heavy appliances together.
Start by listing the loads you need during an outage: lights, fans, refrigerator, router, maybe one aircon, maybe a pump. That list, not a brochure, decides the battery size.
Questions to ask before you buy
- What is the battery brand and model, and its usable capacity in kWh?
- What is the warranty, in years and in cycles or energy throughput?
- Which circuits are on backup, and which are not?
- What happens at the moment the grid fails: is there a pause, and will my devices notice?
- If I start with grid-tie, can this inverter take a battery later, or would I need to replace it?
That last question matters. If outages are a “maybe” for you, one option is to start with a correctly sized grid-tie system and add storage later, provided the equipment allows it. Ask for that in writing.
The short version
Buy a battery to solve a real problem: outages that hurt, or evening use that grid-tie cannot cover. If neither applies, a well-sized grid-tie system is usually the better value. Either way, the decision should start from your bill and how you live, not from a package.
Solarman PH