Serial number
What are we sizing?
Pick the sector, then start from a scenario or build the load list yourself.
Start from a scenario (optional — you can change everything afterwards)
Build the load list
Set how many of each, how many hours a day it runs, and how important it is during an outage.
Enter the connected load of each category in kW — straight off the DB schedule or the single-line diagram — with its running hours and how important it is during an outage.
Diversity (coincidence factor)
The share of the total demand assumed to happen at the same instant. 1.00 counts every load together — the safe reading, and the default. Lower it only if you know this site never runs everything at once; the plant shrinks in proportion.
Something not in the list?
Add it with its nameplate rating.
A load category that isn't listed?
Add the block with its connected kW and how hard it is worked.
Loads
Connected load
Daily energy
Classification
Site & system assumptions
How the site is supplied, and how the plant should be rated against it.
Average hours the grid is down each day. Used for the recharge check.
100 % means the array is sized to cover a full day's energy.
Take care with this option. The total load switched on at any moment must stay below the inverter rating — the schedule adds up to kW if everything runs at once.
What this means
- Loads kept on
- Backed-up load
- Backup window
- Rough energy needed
The exact figures come from the engine on the next step, which also applies diversity, motor starting current, inverter losses, depth of discharge and ageing allowance.
Sized as
Connected load
kW continuous
Driven by . Backing up the whole site would need .
Battery storage
kWh nominal
Holds of load for , sized by .
Solar array
kWp
About × modules, yielding .
How these numbers were reached
Every intermediate figure, so the design can be checked rather than trusted.
Total load
- Connected (nameplate) load
- After demand factors
- Diversity (coincidence) factor
- Coincident peak demand
- Worst-case starting demand
- Daily energy
- Annual energy
Backup subset — and above
- Loads in the backup group
- Connected backup load
- Backup peak demand
- Starting surge to ride through
- Average draw over the window
- Energy over
- …at the battery terminals
- Usable fraction planned against
Sized by peak
Sized by motor start
Sized by PV input
Battery recharge time
Load split by priority
Share of daily energy in each backup tier.
Where the energy goes
Daily consumption by category.
Load during solar and non-solar hours
The same schedule seen by when it runs. Load during solar hours is served straight off the array; load during non-solar hours has to come from the battery, the grid or a generator — and it is that figure the battery is sized on.
- Daily energy
- Average draw across the window
- Loads running in it
Inverter type
Also workable here: , — the options below are ranked with the recommended type first.
Nothing else suits this supply: every option below is a unit.
Battery sizing basis
The pack holds the energy the backed-up loads draw outside the solar window — the cycle it performs every day of the year. The backup window is shown beside it, and flagged if it would need more than the pack holds.
Non-solar hours
Sets the packDrawn by the backed-up loads between sunset and sunrise, every day of the year. The pack is sized to hold it.
Backup window
Sets the pack ShortEnergy to serve
Usable at the terminals
Nominal capacity
Inverter rating basis
Two defensible answers. The one in force is the choice made on the backup step.
As sized by the system
In useSet by . Loads must be staggered so that no more than this runs at one instant.
Matched to the connected load
In useEvery load in the schedule may run together, with nothing to manage on site.
Backup draw, hour by hour
Power drawn during the outage window. Loads drop out as they finish their daily running time, which is why the tail is lighter than the first hour.
Equipment combinations
Options from the catalogue that meet the requirement, ranked on fit, cost and unit count.
Prices converted to at 1 = , rate updated . This rate is over a day old.
No catalogue combination satisfies this requirement. Either the system is outside the tool's envelope, or the product catalogue needs entries that cover it.
Usable storage
Runs the backup load for
Energy & savings
- Annual consumption
- Annual PV yield
- Consumption covered by solar
- Indicative annual saving
- Grid CO₂ avoided
Savings assume self-consumption at the tariff entered and no export credit. They are indicative only.
Engineering assumptions
These are set in the admin panel and applied to every calculation.
Definitions
What each term on this page means.
Disclaimer
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