SolarBoost Home Breakeven Calculator – Homeowner’s Manual

This guide shows you how to use the SolarBoost Breakeven Calculator to estimate how much grid energy you can avoid and how quickly the R5,000 SolarBoost add‑on could pay for itself. It’s designed for homeowners who have solar PV with an inverter and want to prioritize flexible loads (like a geyser, pool pump, or dishwasher) so that more of their usage happens when solar power is available.

• You already have a solar PV system with an inverter.
• You have household loads such as a geyser, pool pump, dishwasher, and an oven.
• You pay a fixed energy tariff (R/kWh). (Time‑of‑Use can be approximated by changing the tariff and rerunning.)

• Reduce grid imports by automatically turning OFF lower‑priority flexible loads when solar power is insufficient.
• Lower your daily electricity cost and improve self‑consumption of your PV.
• See estimated payback (months/years) for the one‑time SolarBoost price (R5,000 by default).

• Open the calculator (Excel or the web version embedded on your site).
• Enter your inverter size (kW), PV peak (kW), fixed tariff (R/kWh), and the SolarBoost price (R).
• Adjust load ratings (kW). Mark flexible loads and set their priority (1 = first to shed).
• Click Recalculate (web) or check the Dashboard (Excel) to see daily grid import, costs, and savings.
• Review the payback estimate. If it’s higher than expected, try making the geyser/pool pump flexible or shifting their schedules to solar hours.

Inverter AC limit (kW)

Your inverter’s maximum continuous AC output. Typical homes: 3–8 kW.

PV array peak (kW)

The sum of your PV panels’ peak DC capacity. E.g., 4.0 kW.

Fixed tariff (R/kWh)

Your current energy rate. Example: R2.50/kWh.

SolarBoost price (R)

One‑time cost of the device (default R5,000).

BaseLoad (kW)

Background usage that is always on (e.g., routers, lights). Default ~0.5 kW.

Load ratings (kW)

Approximate power of each device: Geyser ~3 kW, Oven ~2.5 kW, Pool pump ~1 kW, Dishwasher ~1.2 kW.

Flexible?

Yes (Y) if a load can be temporarily switched off by SolarBoost, No (N) if it must run when scheduled (e.g., oven).

Priority

When power is tight, shed smaller numbers first. Example: 1=Geyser, 2=Pool pump, 3=Dishwasher.

• Oven: 18:00 (dinner time, non‑flexible by default).
• Geyser: 06:00–07:00 and 18:00–20:00 (typical bath/shower windows).
• Pool pump: 10:00–14:00 (runs under midday sun).
• Dishwasher: 20:00–21:00 (evening run).
• You can change any schedule (0/1 flags per hour in Excel; in the web version the default schedule is built‑in).

• The calculator simulates each hour of the day.
• Available solar (kW) per hour = min(Inverter limit, PV peak × PV profile).
• Demand (kW) = BaseLoad + (active appliances).
• If demand exceeds available solar, SolarBoost sheds flexible loads in priority order until the deficit is removed (e.g., Geyser → Pool → Dishwasher).
• Grid import (kWh) is the remaining demand that solar cannot cover.

• Daily Grid Import (kWh): Lower with SolarBoost means real savings.
• Daily Cost (R): Daily grid import × tariff.
• Daily Savings (kWh/R): Difference between ‘w/o SB’ and ‘WITH SB’.
• Payback: Months and years to recover the SolarBoost price from average monthly savings.

• Try higher PV peak (kW) to see the impact of future panel upgrades.
• Edit BaseLoad (kW) to match your home’s background demand.
• Toggle flexible (Y/N) and move priorities to see which shedding order saves more.
• Shift geyser use toward solar hours (e.g., 10:00–14:00) for bigger savings.

• No battery is modelled in the simplified tool (battery discharge can be considered by increasing available power during non‑solar hours).
• Fixed tariff. If you are on Time‑of‑Use, you can approximate by rerunning with a higher evening tariff and a lower daytime tariff and averaging results.
• Device ratings are approximate; actual draw may vary.
• Weather and seasonal PV changes aren’t included; the PV curve is a generic bell shape.

• Charts not showing savings? Ensure at least one flexible load is ON during evening hours, and tariff > 0.
• Savings too small? Increase BaseLoad realism, set realistic device kW, or move geyser run times toward the day.
• Payback ‘N/A’? That means monthly savings = 0. Reduce inverter/PV values or enable flexible loads so the model shows some grid import to offset.

Will SolarBoost work without the internet?

Yes. Once configured, it prioritizes loads locally.

What if my geyser is on a thermostat?

SolarBoost switches the circuit; when solar is tight, it can turn the geyser off regardless of thermostat calling.

Can I add more flexible loads?

Yes in the full model; this simplified tool shows the concept with up to three.

Does SolarBoost replace my inverter?

No. It sits alongside, orchestrating when flexible loads run.

No personal data is needed to use the calculator. If you embed the web version on WordPress, it runs entirely in the browser.