Most "solar software" is built for grid-tied rooftop PV — roof modeling and financing, not battery banks and DC wiring. And most proposal tools are generic document builders with no engineering behind them. If you install off-grid, marine or van/RV electrical systems, you need both: a real design engine and a client-ready proposal. Here’s what to look for.
| Wattonomy | Most other tools | |
|---|---|---|
| Designs DC battery systems | Yes — banks, inverters, DC-DC, 12/24/48V | Grid PV tools: no · Proposal tools: no |
| Sizes cable, fuse & AIC to standard | Yes — ABYC/ISO/BS/AS-NZS | Grid PV tools: PV only · Proposal tools: no |
| Wiring diagram + build pack | Yes | Rarely |
| Branded client proposal | Yes — e-sign + deposit | Grid PV tools: yes · Proposal tools: yes |
| Marine / van / RV ready | Yes | Mostly no |
| Price | From $29/mo | Grid PV: free–$220/mo · Proposal: $20–$100/mo |
Based on publicly available information as of mid-2026. Check each vendor’s site for current details.
Honest take: if you sell grid-tied rooftop solar, a dedicated grid-PV design tool will serve you better, and if you only need to format documents a generic proposal tool is cheaper. Wattonomy’s niche is the overlap nobody else covers well: engineering-grade off-grid, marine and RV DC design and the client proposal, in one place.
For off-grid, marine, van and RV electrical work, Wattonomy sizes the whole DC system — battery, inverter, DC-DC, cable, fuse and AIC — to ABYC E-11, ISO 13297, BS 7671 or AS/NZS, then hands you a branded client proposal with e-sign and a deposit request. From $29/mo, month-to-month, with a free no-card trial.
Two things in one: a design engine that sizes the battery, inverter, charging and — critically — the DC wiring and fusing to a recognized standard; and a proposal that turns it into a credible client document. Generic solar or proposal tools only do half.
General solar and proposal tools range from free to a couple of hundred dollars a month. Wattonomy is $29–$129/mo and does both design and proposal for the off-grid and marine niche.