Using Ultility Bill to Estimate Solar Power Usage

I’m just in the R&P (Research and Planning) phase of my solar system so I have many many questions. Your site is a real trove of great info. Thanks for your generously sharing your expertise.

To start with a simple question i.e. is it acceptable to use my current monthly utility bill to calculate the size of our yet-to-be solar system? In most solar websites and videos, the experts all recommend using a special meter to measure the power of every single household AC device. It just seems like it would be so much easier and faster to use the power consumption from my current power utility bill. Am I missing something?


Welcome back @chewface! Firstly I want to suggest that you and @Ronny_Mauldin might want to share notes. Looks like you’re both trying to work out how to get some reliable electricity in the Philippines.

I’m no off grid expert, so hopefully someone can jump in on this one, but my understanding is that for an off grid system using your current electricity usage is not a great way to size an off grid system. Why? Because no. 1 thing you want to do when going off grid is to reduce as much electricity usage as possible. But probably more importantly, it’s not just your daily energy usage that you want to consider, it’s your peak power consumption that will help dictate the battery and inverters that you need.

Like I said to Ronny, I think you’d do very well to have an off grid solar designer in Australia design the system for you, money well spent I think.


Hi Willam, if you can just use your bill to do the estimate,
You are not sure if you going to install battery sys , then you might be given the monitoring sys as part of the package, or even with just Grid connect sys you are NOT decided which inverter you are going to use, .

Thank you
Mel Solar Hybrid Solutions

Hi Mel, Martin, Jason;
Thks for your respective replies.

In the Philippines, esp in the provinces outside Manila, you can find only solar equipment ‘installers’ (however not easy to find an experienced one).
Therefore, solar customers (like me) must buy the solar gear (including the inverters) or allow the installer to buy it, but as you might expect, at a (much) higher marked-up price. Warranties are only from the manufacturers.

FYI, the electric utilities do NOT buy any excess power produced from solar set-ups and in some places, off-grid solar systems are not permitted. However, as long as I pay for a back-up grid tie, then I should be able to run off my solar system 95%+ of the time…

One installer who i have contacted recommended installing qty-2 5KW “Axpert MKV” inverters (Taiwan brand I think). However, he was totally unfamiliar with LiFePO batteries or their set-up, which is why I am doing the research myself. Also another system he installed is starting to fail after only 4 years, which I suspect is due to the lack battery balancing circuitry…

How much would it cost to have a ‘professional’ design my solar system?