Engineering for solar and storage decisions
Yield assessments, battery sizing, design and technical due diligence for solar, solar-plus-storage and wind-solar hybrid projects, from gigawatt portfolios to factory rooftops. Senior engineers working with our own AI-powered simulation tools deliver bankable results in days, not weeks.
50+ GW
solar and storage projects supported
10+ countries
across five continents
Since 2019
serving developers, investors and advisors
Trusted by leading renewables developers and advisors
Built for everyone who signs off on a project
Developers
Find out which sites are worth pursuing before you spend on detailed design. Screening, design and yield assessments that hold up at financing.
Pre-feasibility and go/no-go · Layout and configuration · Energy yield assessment · BESS sizing
Investors
Independent review of assets and portfolios before you acquire or commit capital.
Pre-acquisition due diligence · Multi-site portfolio review · Operational performance review · Long-term energy forecasts
Lenders
Lender's technical advisory from financial close through operations.
Design and resource basis review · Risk registers · Conditions precedent support · Yield reconciliation
Advisory firms
Engineering capacity for your projects, delivered in your report format.
Subcontracted yield and DD · Simulation-ready timeseries · Portfolio-scale reviews · Retainer support
Energy users
Factories, commercial sites, data centres and EV charging hubs sizing solar and storage to their own load.
Load and tariff analysis · Rooftop and captive solar · Peak shaving and backup · EV charging energy planning
Project types
Engineering judgment, with AI in the workflow
Layout, energy model and financial model delivered as one consistent package. When a grid limit, tariff or capex assumption changes, we re-run the analysis in days instead of redesigning. Our engineers set the scope, judge the results and sign every deliverable.
Scoped by an engineer
A 30-minute call to agree the question and the analysis that answers it.
Simulated and checked at scale
Tomsawyer’s Timeseries Energy Engine capable of High Temporal Resolution (HTR) energy simulation for accurate solar, battery storage and hybrid RE decision-making. Applied for real projects around the world since 2019.
Reviewed and signed off
Reports, models and data your lenders and partners can trace back to source.
Maximise equity IRR. Keep capex under $55M and minimum DSCR above 1.30. What mix?
14.2%within limits
84 MWp · 90 MWh
13.8%
78 MWp · 100 MWh
13.1%
92 MWp · 60 MWh
EQUITY IRR
14.2%
LCOE
$48/MWh
MIN DSCR
1.34
CAPEX
$54.0M
What we deliver
Simulation-ready timeseries
Energy timeseries built on real weather history, not a single typical year.
- Multi-source irradiance validation and temperature profiling
- 20+ years of historical data, not only TMY
- Location-, equipment- and design-specific generation
- Sub-hourly resolution for high-stakes projects
Deliverables: CSV/Excel timeseries, source comparison
Simulation-ready timeseries
Energy timeseries built on real weather history, not a single typical year.
- Multi-source irradiance validation and temperature profiling
- 20+ years of historical data, not only TMY
- Location-, equipment- and design-specific generation
- Sub-hourly resolution for high-stakes projects
Deliverables: CSV/Excel timeseries, source comparison
System configuration modeling
Every equipment and configuration mix, compared on energy and cost.
- Tracker vs fixed-tilt, rooftop and carport options
- DC stringing, tilt, pitch and DC/AC ratio optimisation
- Energy and cost matrix across hundreds of options
- The configuration with the highest return, identified
Deliverables: configuration matrix, IRR ranking
Layout design
Site-adapted layouts for ground-mount and rooftop solar, ready for planning.
- PV stringing optimised for performance and cost
- BESS and inverter siting
- Land-use and terrain constraints from SRTM, satellite imagery and stakeholder input
- CAD and PDF layouts for planning and approvals
Deliverables: CAD + PDF layout, block plan
Energy yield assessment
P50/P90 energy yield from PVsyst, with each loss factor documented.
- P50, P90, TMY and historical timeseries simulations
- Soiling, electrical and shading losses, including complex urban sites
- Side-by-side yield comparison across designs
Deliverables: P50/P90 energy yield from PVsyst on 20+ years of data. Every loss factor documented.
Battery storage assessment
Battery sizing matched to your load, tariff and revenue case.
- Solar-BESS pairing analysis
- Sizing recommendations with cost-benefit
- DC-coupled storage and dispatch modelling
- Behind-the-meter storage for peak shaving, demand charges, EV charging and backup
Deliverables: Prove the storage business case before you commit. Battery size and dispatch are modelled together with the PV design, tariff and grid limit.
Technical due diligence and lender's advisory
Independent review from pre-construction bankability to operational hindcasting.
- Pre-construction and financing: design basis, resource assumptions, equipment and construction readiness
- Bankability reports, risk registers and CP support to financial close
- Acquisition and operations: pre-acquisition review of design, contracts, permits and technology risk
- Hindcasting, yield reconciliation and revised production estimates
Deliverables: IE-style report, risk register, revised P50
200 MW solar + 80 MWh BESS
Pre-construction · lender's technical advisory
Multi-source validated, within 2% of independent estimate
Configuration confirmed optimal for site conditions
Inverter firmware update required for grid code
Risk register complete, CP inputs delivered to lender
Grid approval pending, 8-week delay risk
350 MW portfolio (3 sites)
Acquisition review · operational + pre-construction
P50 overstated by 3.1% at Site B; revised estimate provided
PPA terms and EPC scope consistent with design
Hindcast shows 4.2% underperformance at Site A; soiling suspected
Module and BESS technology reviewed, no red flags
Operational performance review and long-term energy forecasts
An accurate view of what an operating plant will produce over its remaining life, for acquisitions, refinancing and asset management.
- Monthly reconciliation of irradiance, energy, PR and availability against expected values
- Root cause analysis of underperformance: soiling, degradation, availability and curtailment
- Satellite-bias correction and yield re-modelling from operational data
- P50 to P99 forecasts over one-year and ten-year periods for the remaining asset life
Deliverables: performance review report, remaining-life P50/P90 forecast, Excel model
Remaining-life forecast · 100 MWp operating plant
| Year | PR | P50 GWh | P90 GWh | P99 GWh |
|---|---|---|---|---|
| 2027 | 78.9% | 158.2 | 151.4 | 145.0 |
| 2032 | 76.4% | 153.1 | 146.6 | 140.3 |
| 2037 | 74.0% | 148.3 | 141.9 | 135.9 |
| 2042 | 71.6% | 143.5 | 137.3 | 131.5 |
| 2047 | 69.3% | 138.9 | 133.0 | 127.3 |
Built from monthly operating data: measured irradiance, energy, PR and availability, reconciled against expected values before forecasting.
Case studies
Proven success in solar and battery storage development
Data centre · United States
5 GW
100% green energy feasibility for an AI data centre hub
Hourly solar production profiles across 5 GW for one of America's largest behind-the-meter AI data centre hubs, delivered in days instead of months.
C&I rooftop · Middle East · pre-investment review
+2.3 to 2.7% IRR
Design optimisation for a solar and EV charging developer
A late review, with equipment already fixed after months of in-house design. Design iteration time cut by 75%. Engaged at the design stage, optimisation has delivered 20 to 30% higher IRR.
Utility-scale portfolio · Australia
15.3 GWp in 3 weeks
Investment-grade pre-feasibility for a Queensland solar portfolio
Layout and yield assessed site by site across 15.3 GWp in three weeks, so investors knew which projects to prioritise before committing further development spend.
Technical due diligence · Africa and Middle East
>1 GWp
Automated due diligence for a global advisory firm
Operational data processing, satellite-bias correction, batch yield re-modelling and DC/AC design audits, producing bankable P50/P90 forecasts.
Simulation data · hybrid projects
Weeks to hours
On-demand solar datasets for a hybrid advisory firm
Multi-source irradiance validation and equipment-specific simulation, ready for the firm's own hybrid modelling workflows.
Working on a similar project?
Tell us the site and the question. We'll figure out the analysis on a 30-minute call.
Who you work with
Bishal Madhab
Principal Engineer and Founder
Bishal has spent 13 years modelling solar, wind and battery storage. At DNV-GL he was Energy Storage Lead for Asia Pacific and helped build its battery storage advisory practice. His early career was in energy modelling research, at Carnegie Mellon and a US-India solar research consortium, with peer-reviewed work on PV variability. He co-founded an ML forecasting startup deployed across 2.5 GW of solar and wind projects, and built Tomsawyer's simulation engine from the ground up.
Testimonials
What our clients say
"Tomsawyer performed the work competently and met our expectations throughout the project. They showed a diligent approach and attention to details, and worked in a professional manner, ensuring that the tasks were completed on time and to the required standards. We were satisfied with the quality of their work and appreciate the support they provided."
Ignacio Becares
Principal Consultant, DNV AS
"It was a pleasure to collaborate with you, and I really appreciated the fact that you understood our sense of urgency and managed to adapt to our short timelines. The pre-feasibility study documentation was according to our expectations, and you even went beyond with helping us selecting some initial equipment to provide energy estimations."
William Gaillard
Former Wind Head, Carbon Resilience
"The Tomsawyer team was instrumental in supporting the technical layout design for our first utility-scale solar development in the UK, up to securing planning consent. Their sound knowledge of solar optimization enabled the production of an efficient layout, integrating DC-coupled BESS."
Ashley Vandermeer
COO, Naseby Energy Holdings
"Tomsawyer helped us clearly understand the long-term techno-economics of distributed energy asset and sensitivities with respect to configuration changes. They were very collaborative and provided efficient and highly professional support."
Andrew Koh
Managing Director, Megawatts
"What I would say about Tomsawyer is that you are very professional, very dedicated to the work delivering to BBCO Energy. Tomsawyer delivered its advisory service in timely manner, with high responsibility, and caring about customer's problems. I do believe, Tomsawyer will add very good value to its partners/customers by delivering their high quality of work."
Khanh-Loc Nguyen
CEO, BBCO Energy Vietnam
Projects across 10+ countries
- Americas
- Europe and the UK
- Africa and the Middle East
- South and Southeast Asia
- Australia
