Pillar 1
Solar sizing for high load homes
A rigorous, DIY friendly approach for prosumers with EVs, heat pumps, workshops, pools, or high baseline loads. Use this guide to size an array that is realistic given roof, inverter, and interconnection constraints.
Framework
This pillar locks the first requirement: how much energy you want solar to produce annually. It does not assume you want full offset. High income prosumers often prioritize resilience and peak shaving, not just payback.
Step order that prevents expensive mistakes
- Set your target: full offset, partial offset, or resilience first.
- Translate utility usage into daily energy and annual energy.
- Estimate local production per kW using peak sun hours and realistic system efficiency.
- Apply constraints: roof area, shading, inverter limits, and utility interconnection caps.
- Only then choose hardware and rack style.
Quick sizing tool
Use this for a first pass. You can refine later with site specific shading, roof geometry, and utility rules.
Tip: Use location to auto fill sun hours. Zip stays visible and editable.
We show a conservative size range. Use this to decide what class of gear you are shopping for.
Output includes estimated size range, rough cost range, annual spend, and payback range.
Case study
Running a 1 ton 48V DC heat pump on 1.44 kW of solar in Climate Zone 4A
Common constraints you must check
Roof area and layout
Panel count is limited by usable area, setbacks, and azimuth. A simple kW target can be impossible on a complex roof.
Utility interconnection caps
Some utilities cap inverter size or export. Design to what is allowed, then decide on storage to capture surplus.
Inverter and string limits
MPPT windows, string voltage, and cold weather Voc can break naive designs.
Shading and partial production
A small amount of shade can crush production. This is where optimizers or microinverters can be worth it.
Cold weather note: string voltage rises as temperature drops. Confirm panel Voc at your design minimum temperature.
Bill of materials starter
This is a checklist so you know what you are pricing. Use it to avoid missing balance of system costs.
- Modules: panel type, wattage, count, and mounting style.
- Racking: rails, clamps, flashing, and grounding hardware.
- Inverter: string, hybrid, or microinverter architecture.
- Combiner and disconnects: rapid shutdown, service disconnect, labeling.
- Wiring: PV wire, conduit, breakers, and surge protection.
- Monitoring: production and consumption CTs.
- If storage: battery, BMS integration, and critical loads panel.