Quick answer
You need half-hourly data for a final battery size, annual saving and payback. You can still give a budget quote before it arrives, using clear assumptions and provisional costs. Then update the battery size and financial figures once you have modelled the client’s actual half-hourly load.
The short answer is:
- Full quote (Yes): You need half-hourly data if you want your commercial battery quote to include the final battery size plus expected annual saving and payback
- Preliminary quote (No): You don't need it if you want an early budget quote, which shows the client a provisional scope, rough installation cost and the figures you will confirm once you've got the half-hourly data
CFOs and finance directors want a quote they can trust and take to the board. If you can't produce the full quote yet, you've got three options:
- Guess at a size and a payback to keep the sale moving forward
- Wait for the half-hourly data before sending the client the full quote
- Give the client a budget quote now, ask them for the half-hourly data, then send the full quote including battery size, savings figure and payback once you've modelled the load profile
The problem with the first approach is the finance lead will interrogate the figures you've guessed at. If they pick a hole you can't plug, they lose trust in you and the quote.
The second approach is the most cautious, but a competitor could get a budget quote in first while you wait.
The third approach is usually the best route. You give the client the parts of the job you can price now, with a real price range and scope to consider, without committing to the figures you can't back until you've modelled the data. So there are fewer unsupported numbers for finance to pull apart.
To strengthen your proposal further, use a free simulator like GridVolt's to test different battery sizes and tariffs against their own half-hourly data live in front of the client. Let them alter the inputs so they can see how their modelled savings and payback change in real time.
What you can put in a pre-half-hourly data quote
Treat the first quote as a budget quote. Cover the parts of the job you can price before you've got the half-hourly data, like:
- An assumed battery and inverter size in kW and kWh
- The EMS controller, meter, CTs and standard commissioning
- Survey, design and DNO application fees
- Software, monitoring and support charges
- Allowances for cabling, switchgear, groundworks and site access
Tell the client which of these are fixed, which are assumptions and which prices might change after the survey. Spell out your assumptions (and how you arrive at them) on the:
- Switchboard
- Cable runs
- Battery location
- Fire requirements
- Internet connection
- Existing metering
That gives the client enough to judge whether the project fits their budget. Just warn them the battery you recommend could get bigger, and cost more, once you have the half-hourly data to work from.
The Distribution Network Operator (DNO) is the company that runs the local grid the site connects to. They decide how much power your client's site can draw and how much it can send back. Until the DNO has reviewed the application, you won't know whether it will approve the connection as proposed or attach conditions, like upgrade work or a limit on how much your client can export. Either can change the installation price, programme or export value.
So put the DNO cost in as an allowance, not a set price, and tell the client it could go up and why. When you hear back from the DNO, you can replace the allowance with the confirmed cost.
What needs to wait for the half-hourly data
Leave the final recommended kW, usable kWh, savings and payback until you've got the half-hourly data.
That's what tells you when the client's site uses power, how high the peaks are, how long they last, and how demand changes across working days, weekends and the seasons. Until then, don't commit to:
- The final battery kW and usable kWh
- Peak-shaving or tariff-shifting savings
- How much spare solar the battery can store
- Expected battery cycling
- GB client-specific trading income, where the site qualifies
- Payback and ROI
Those last two, payback and ROI, are the numbers that decide whether the job actually stacks up for the client. An annual bill won't give you what you need, because it shows you the total kWh but tells you nothing about when the site actually draws that power.
For example, two sites might each use 500,000 kWh a year. At one, demand hits 200 kW for half an hour and drops straight back. At the other, it hits 200 kW and stays there for three hours.
The battery has to cover the part of the peak you want to reduce, for as long as that peak lasts. So the second site needs far more usable storage than the first. The yearly total is the same, but that bigger battery costs the client more and changes the saving, so you end up quoting a different payback on each site. The annual bill would have shown you none of that.
Related questions
How do I get and check a client's half-hourly data before sizing a battery?
How do I size a commercial battery for the best payback?
Where's the line between a free battery estimate and paid feasibility work?