Ten questions to ask before you accept a solar proposal
A good proposal answers most of these before you ask. If yours does not, ask them. The answers show whether the saving on the front page will survive your site.
In short
- Fixed, energy, demand and power-factor charges respond to different fixes.
- One short peak can set the demand charge for a whole month.
- Twelve months side by side show patterns that one bill hides.
- Fix the bill first. A cleaned-up baseline changes how much solar or storage you need.
The charges you will usually find
Which charges apply, and how they are calculated, depends on your utility and your tariff category. Check the detail against your own tariff schedule. In general, a commercial bill combines some or all of these:
- Fixed or service charges
- Charged whatever you use. Usually linked to your supply size or tariff category.
- Energy charges
- Charged per kilowatt-hour (kWh) consumed. Some tariffs vary the rate by time of day or season.
- Demand charges
- Charged on your highest power draw in the billing period, in kW or kVA, usually measured over a short interval. One brief peak can set the charge for the whole month, even if the rest of the month was quiet.
- Power-factor or reactive-energy charges
- Some tariffs penalise equipment that draws reactive power, such as motors and compressors running at low load. Poor power factor can raise your kVA demand or attract a separate charge.
- Taxes and levies
- Added on top. You usually cannot change them, but check they are applied correctly.
Five checks on your last 12 months
Put twelve months of bills side by side in one table: consumption, maximum demand, charges by type and the total. Then ask:
- Is the tariff category right for your load?Sites change over time. A tariff that suited you when the supply was connected may no longer be the cheapest option, or the one you are meant to be on.
- Are the readings actual or estimated?Estimated readings can drift away from real use and produce a large catch-up bill later. Check the bill for how each reading was taken.
- Does demand spike in particular months?Compare maximum demand month by month. A single month well above the rest points to a one-off cause, such as several large machines starting at once, that is often fixable.
- Is power factor flagged?Look for reactive-energy charges, or a kVA figure much higher than kW. Correcting power factor is a well-understood fix.
- Does the bill match what you use?Reconcile against your own sub-meters or production records where you have them. Look for charges that are new, unexplained or applied to the wrong site.
What to do with what you find
Some fixes are operational: staggering equipment start-up, moving a process to cheaper hours, correcting power factor. Some need a billing query with your utility. Only after those should you size a capital project, because the cleaned-up baseline changes how much solar or storage you actually need.
If your bills show a pattern you cannot explain, or you want a second pair of eyes, send us your last 12 months. A bill review is the lowest-commitment way into an energy audit, and it stands on its own.