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Solar Feasibility Software
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Know the right solar and battery size before you design
SolarPlus Feasibility Assessment is solar feasibility software that sizes solar and battery storage against a site’s real consumption and tariff, in dollars, before any design work begins. It prices and ranks thousands of combinations by NPV, payback, IRR, cost of energy or self-sufficiency, then builds any chosen options into complete system designs, so installers and EPCs can present business owners and CFOs with options they can defend.
Settle the size before the design
Size from the site's own numbers
The right system size depends on how a site uses energy, what it pays for it and what it can export. Feasibility Assessment starts from the consumption profile and tariff, so the size you propose comes from the customer’s own data.
Qualify before design hours are spent
A detailed commercial solar design takes time. Running feasibility first shows whether a project stacks up, and at what size, before anyone lays out panels or builds the electrical design.
Show the case for storage
A battery changes both the capital cost and the return. Feasibility Assessment compares solar only against solar plus storage and states the incremental cost and payback of adding the battery.
How a solar feasibility assessment runs
The sections below follow the order of the tool, from site data through to system designs that are ready to compare and propose.
Start from real site data
Run feasibility from a consumption profile and tariff, before any design work.
Priced on real consumption data
Feasibility Assessment runs as soon as a system has a consumption profile and a tariff. Savings are priced against the site’s real import, export and demand rates, and solar output is modelled from the site’s location. No panel layout is needed, so a solar feasibility study can be completed before design hours are spent.
Consumption profile
Every result is driven by the site’s consumption profile, built or imported in the Profile Builder. Interval meter data uploads as a CSV file in a range of formats, at intervals from one minute to 60 minutes.
Sites without interval data
Where no interval data exists, SolarPlus can estimate a full-year consumption profile from a bill total, billing period and tariff. Weekday time-of-use usage and monthly volumes can then be varied to suit the client’s scenario.
Tariff
Savings are priced against the tariff set for the site, including time-of-use rates, export rates and demand charges, so results reflect how the site buys and sells energy.
Drawn roof surfaces (recommended)
Drawing roof surfaces in Map Design before running feasibility gives the model real pitch and orientation, and lets roof capacity fill in from the available panel positions. Results sit closer to the designed system.
Site location
The site is geocoded and solar output is modelled from irradiance at that location. Feasibility models a generic array at this stage, and the detailed layout comes later.
Choose the objective and ranges
Choose what to optimise for, then set the sizes to compare.
Rank options by what matters
Feasibility Assessment works as PV system sizing software. Each run tests array sizes, battery sizes, battery strategies, tariffs and hundreds of monthly peak-shaving and grid-charge setpoints, with no limit on the number of combinations, then ranks every option by a single objective. Only the objective and the size ranges are needed to get a result.
Highest lifetime value (NPV)
Recommends the option with the largest total gain over the analysis period. It tends toward larger systems, so check the result against the roof and the budget.
Fastest payback
Recommends the option that returns its capital soonest. It tends toward smaller systems that pay back quickly and earn less over their life.
Best return (IRR)
Recommends the option with the highest rate of return on capital, which helps when the project competes with other uses of the same money. Its bias is similar to payback.
Lowest cost of energy
Recommends the option with the lowest cost per generated kWh (LCoE). It ignores self-consumption, which limits its use on most commercial sites.
Most self-sufficient
Recommends the option that meets the largest share of the site’s load on site. It favours independence from the grid over financial return.
Solar-only and battery comparison
Compare solar-only options against solar-plus-battery options side by side, or switch battery storage off to size the array on its own.
Size ranges and increments
Set a minimum, maximum and increment for the array (kW) and the battery (kWh), plus a battery C-rate. Leave a range blank and this solar sizing tool sets it automatically from annual consumption.
Detail versus speed
A slider trades resolution against run time and shows how many combinations will be evaluated. A finer grid can find a better optimum and takes longer. The choice is yours, and a run seldom takes more than 20 seconds.
Set realistic battery dispatch assumptions
Test every battery strategy by default, or focus on one.
Battery returns you can defend
How a battery operates has a large effect on its modelled return. By default, Feasibility Assessment tests every battery strategy, so the recommendation covers how to run the battery as well as what size to install. To focus a run on one strategy, choose it from the options below, including the operating mode already set in the system’s battery modelling.
Match this system's settings
Focuses the run on the battery’s configured operating mode, so a battery set to discharge in the expensive tariff period is modelled that way, and a self-use battery discharges whenever there is a shortfall.
Discharge whenever needed
The battery covers any shortfall at any hour, holding back a 10 per cent reserve. Treat this as an upper bound on battery benefit and expect an installed system to deliver less.
Peak periods only
The battery discharges only during peak tariff periods. On a flat tariff this setting produces no battery benefit, so use it where the tariff has a peak rate.
Demand peak shaving
Holds grid demand below a threshold to reduce demand charges, on tariffs that have them. You choose the periods in which the battery meets load in full.
Grid charging for peak shaving
Allow off-peak charging from the grid and set the state of charge to reach before the next peak. Without grid charging, a site that self-consumes most of its solar has little surplus to charge from.
Apply budget, roof and export limits
Constrain the options by capex, roof capacity, export limit and inverter rating.
Recommendations that fit the site
Constraints remove options the project could never build. A capex budget excludes anything over the limit, roof capacity caps the array, and export and inverter limits rule out oversized systems. Costs and financial assumptions then set the capex and return of every option that remains, so the recommendation is one the customer can proceed with.
Capex budget
Set a maximum capital spend. Options that cost more are excluded before they are evaluated, so every result fits the budget.
Roof capacity
Caps the array size that can be recommended. Where roof surfaces and a panel grid have been drawn, it fills in automatically from the available panel positions. If it cannot be determined, the page warns you.
Array area and density
With no panel grid to count from, enter an array area and a density to calculate roof capacity: roughly 200 W/m² for flush panels on a pitched roof, or 120 to 150 W/m² for tilted rows on a flat roof.
Array tilt
Use each drawn surface’s surveyed pitch and frame angle, tilt every surface to the site’s latitude, or apply a single angle to test a racking choice.
Export limit and inverter sizing
Set an export limit in kW (zero for a zero-export site), an inverter rating and a maximum DC:AC ratio. Array sizes that would be oversized for the inverter are excluded.
Costs and rebates
Enter a cost per kW of solar, a cost per kWh of storage, a fixed install cost and any rebates. These drive the capex, payback and NPV of every option.
Financial assumptions
Set the analysis period, load growth, discount rate and tariff escalation. Leave discount rate and escalation blank to inherit the site’s values, which keeps feasibility consistent with the return figures on the quote.
Read the recommendation in dollars
See the recommended size, the scenarios and where the saving comes from.
Make the storage decision explicit
Results open with the site’s current annual bill beside the recommended option’s size, capex, payback and lifetime value. A scenario comparison sets business as usual against solar only and solar plus storage, and states the incremental cost and payback of adding a battery, so the case for or against storage is plain.
Summary tiles
The baseline annual bill with no solar or battery, next to the recommended option’s size, capex, payback and lifetime value. A line beneath states how many options were compared and the ranking rule in plain English.
Scenario comparison
Three cards side by side: business as usual, solar only, and solar plus storage. Each shows Year 1 saving, net capex, NPV, payback and self-sufficiency.
Storage uplift
Where storage adds value at the same array size, a line states the extra capex, the further annual saving and the incremental payback of the battery.
Where the saving comes from
The first-year saving is split into grid purchases avoided, demand charge reduction and export credit. When export credit exceeds 35 per cent of the saving, it is flagged as a caution to raise with the customer.
Value against spend
A chart plots every option by money spent against return, with a line tracing the best value at each spending level. Switch the vertical axis between NPV and payback.
Results table
Every combination evaluated, sortable by column: PV size, battery size, net capex, Year 1 saving, payback, discounted payback, NPV, IRR, LCoE, export dependency, self-consumption, self-sufficiency and extra NPV per kW.
Test and defend the recommendation
Check whether the recommended size still wins when the assumptions change.
Know what moves the answer
Feasibility Assessment shows the assumptions behind every recommendation. A sensitivity test reports how often the recommended size still wins under varied tariff escalation, discount rate, feed-in rate and installed cost. Every assumption is tagged with where it came from, which makes the result defensible in front of a finance team.
Sensitivity test
Tests whether the recommended size still wins under different assumptions, including tariff escalation, discount rate, feed-in rate and installed cost. It re-prices options already modelled, so the result is instant.
How often the size wins
The headline states in how many of the tested scenarios the same size remains the recommendation, and a chart shows which single assumption moves the outcome most.
Assumption provenance
Every figure driving the result, from cost per kW to discount rate, degradation, dispatch method and irradiance source, is tagged as coming from the site record, a business default, a generic fallback or a value typed in.
Rates left on a default
A rate tagged as a default is a prompt to set it properly before quoting, so a generic figure does not reach a customer unnoticed.
Estimate flag
When no roof surfaces are drawn, the page flags that it is working from an estimated tilt, and those results should be treated as an upper bound.
Tie-breaks
Where two options score closely, the tie-break is applied automatically and stated in plain English above the results table, so you can see why one option ranked first.
Reuse settings across your team
Save complete input sets as presets the whole business can use.
Consistent assumptions on every project
Feasibility runs on the same system as the rest of the project, using its consumption profile and tariff, and it inherits the site’s discount rate and tariff escalation unless you set your own. Saved settings apply a complete set of costs, financial assumptions and ranges in one step, so the whole team starts from the same figures.
Saved settings
Store a complete set of inputs (costs, financial assumptions and ranges) under a name and apply it in one step. Saved settings hold inputs only, never results.
Shared across the business
Saved settings are available to every user in the business, so a well-built preset for a project type is created once and reused by the team.
Last analysis restored
The most recent analysis for a system is saved automatically and restored, with the inputs that produced it, the next time the page is opened.
Re-run prompt
If the consumption profile, site or tariff has changed since the last run, a banner asks you to re-run instead of showing figures that no longer match the site.
Build shortlisted options into designs
Send any result option to an automated build, then compare the designs.
Several options, designed and compared
Any option in the results can be added to the build process, where SolarPlus generates the complete system design automatically, from panel layout to pricing. Each option becomes a separate design on the project. When the builds finish you are taken to a comparison with performance already generated, ready to present side by side in a customer proposal.
Add any option to the build
Choose any option in the results, whether the recommended one or an alternative, and add it to the build process. SolarPlus then generates the panel layout, electrical design, single-line diagram and pricing for that option automatically.
What carries across
Each option carries its array size, battery size and battery dispatch settings, including monthly setpoints, into the design. The built system matches the option that was modelled in feasibility.
System package and costs
Select a pre-built system package for the build. Pricing is calculated from the package and its line-item formulas, and the package’s RoI settings are applied, so each design is priced the way your business has set it up.
Separate designs on the project
Every option you build becomes its own system design on the project’s contact record. There is no limit on how many options you can build for one site.
Comparison with performance generated
When the builds finish you are taken to the comparison, where performance results are already generated for each design, so the options can be weighed against each other straight away.
Present the options to the customer
Present several configurations for one site on a single customer-facing proposal page. The customer compares them, selects one and continues to acceptance.
Refine the designs
Every aspect of a built design can be edited afterwards, from the panel layout and electrical design to the pricing. Auto-Design can also rebuild the electrical design with a different inverter.
Financing and tax
Feasibility assumes a cash purchase before tax, which keeps the sizing decision separate from financing terms. Finance, payment terms, tax and rebates are configured on the Pricing tab once the system is designed and quoted.
From feasibility to final design
Feasibility Assessment settles what size to propose. The design that follows settles what will be built: shading and panel layout are resolved in design, the system is simulated at five-minute intervals in the performance engine, and finance structures are set in pricing. The table shows what each stage covers.
| Stage | Feasibility Assessment | Designed system in SolarPlus |
|---|---|---|
| Question answered | What size to propose, and whether the project stacks up | What will be built, and what it will return |
| When it runs | Once a consumption profile and tariff exist, before design | After panel layout and electrical design |
| Array | A generic array modelled from site irradiance. Array size is a number | Panels placed on drawn surfaces |
| Shading | Applied in design, once panels are placed | Ray-traced shade analysis, resolved to diode-zone level |
| Panel layout and setbacks | Roof capacity is applied as a limit. Layout follows in design | Laid out with setbacks, walkways and keepouts |
| Finance and tax | Cash purchase before tax | Cash, lease, rental, financed and PPA structures, with tax and rebates set in pricing |
| Path to design | Any result option can be added to an automated build | Each built option is a separate system design on the project, ready to compare |
| Accuracy | Accurate to the constraints and values entered into the model. It is no substitute for full design and modelling of the selected options and a fully priced system | The basis for the customer proposal |
Frequently asked questions
What is solar feasibility software?
Solar feasibility software assesses whether a solar or solar-and-battery project stacks up financially, and at what size, before detailed design. SolarPlus Feasibility Assessment does this from a site's real consumption profile and tariff, pricing and ranking many array and battery size combinations in dollars.
What does SolarPlus Feasibility Assessment do?
Feasibility Assessment sizes solar and battery storage against a site's consumption and tariff before any design work. It prices and ranks thousands of combinations of array size, battery size and battery strategy by a chosen objective, and returns a recommended option with its capex, payback, NPV and IRR.
Can SolarPlus be used as PV system sizing software?
Yes. Feasibility Assessment is PV system sizing software for solar and battery projects. It compares array sizes in kW and battery sizes in kWh against the site's consumption profile and tariff, applies roof capacity, export and inverter limits, and recommends the size that ranks first on the chosen objective.
What do I need before running a feasibility assessment?
A feasibility assessment needs a consumption profile loaded on the system, a tariff and a geocoded site. Drawing the roof surfaces in Map Design first is strongly recommended, because it gives the model real pitch and orientation and lets roof capacity fill in automatically.
Which objectives can the recommendation be optimised for?
Feasibility Assessment can optimise for one of five objectives: highest lifetime value (NPV), fastest payback, best return (IRR), lowest cost of energy (LCoE) and most self-sufficient. The objective decides which option is recommended, and the full results table can still be sorted by any column.
Does Feasibility Assessment compare solar only with solar plus battery?
Yes. Feasibility Assessment models solar-only and solar-plus-battery options side by side, and the scenario comparison shows business as usual, solar only and solar plus storage together. Where storage adds value at the same array size, it states the extra capex, the further annual saving and the incremental payback of the battery.
Can feasibility options be turned into system designs?
Yes. Any option in the Feasibility Assessment results can be added to the build process, where SolarPlus generates a complete system design for it automatically, including panel layout, electrical design, single-line diagram and pricing. Each option becomes a separate system design on the project, with its array size, battery size and dispatch settings carried across, and there is no limit on how many you build.
How does the battery dispatch assumption affect the result?
The battery strategy has a large effect on the modelled return. By default, Feasibility Assessment tests all four strategies (match this system's settings, discharge whenever needed, peak periods only and demand peak shaving) and ranks the results. A run can be focused on one strategy instead. Discharge whenever needed is an upper bound on battery benefit, so treat results from it with caution.
Can Feasibility Assessment account for demand charges and export limits?
Yes. Savings are priced against the site's real import, export and demand rates, a demand peak shaving option holds grid demand below a threshold, and the first-year saving is split to show demand charge reduction. An export limit can be set in kW, including zero for a zero-export site.
How accurate is a feasibility assessment compared with a designed system?
A feasibility assessment is accurate to the constraints and values entered into the model. It models a generic array from site irradiance, so it is no substitute for full design and modelling of the selected options and a fully priced system. Drawing roof surfaces in Map Design first gives it real pitch and orientation. Without them it uses an estimated tilt, so treat those results as an upper bound.
Does Feasibility Assessment model shading, panel layout or financing?
Feasibility Assessment models a generic array from site irradiance, so shading, panel layout and setbacks are left out, and it assumes a cash purchase before tax. Those are handled later in SolarPlus, in the design, shade analysis and pricing stages.
How is Feasibility Assessment different from the Battery Sizing Optimiser?
Feasibility Assessment tests a range of solar array and battery sizes together before design, ranking combinations by NPV, payback, IRR, cost of energy or self-sufficiency. The Battery Sizing Optimiser tests battery options for a completed solar design against simple payback, first-year return or minimum annual cost, and suggests the best battery size, battery strategy and monthly setpoints.
Can feasibility settings be reused across projects?
Yes. In Feasibility Assessment, a complete set of inputs, including costs, financial assumptions and size ranges, can be saved under a name and applied to another system in one step. Saved settings are shared across the whole business and store inputs only, never results.
If you are weighing SolarPlus against other feasibility software such as Orkestra, see our Orkestra comparison. We have also published detailed comparisons with HelioScope and PVsyst covering pricing, modelling depth and workflow.
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