How to Budget & Quote a Solar + EV Charger Install: A Cost Controller’s 5-Step Checklist

I manage procurement for a 30-person electrical contractor in Perth. We've installed about 200 solar and EV charging systems over the past 4 years — roughly $350k in hardware spend annually. I track every purchase order in a shared spreadsheet that has, honestly, saved us more than any discount negotiation ever did.

If you're quoting a system that includes a solar inverter, battery storage, and a Level 2 EV charger — for a client or for your own site — here's the checklist I use. It's not complicated, but skipping one step can cost you 15–20% more than you expected.

There are 5 steps. Each one has a specific check. Do them in order.

Step 1: Define the exact system configuration before asking for quotes

This sounds obvious, but I've made the mistake of calling vendors with a vague "I need a 10kW system and an EV charger." You get three quotes back that are impossible to compare because everyone assumed different things.

What to specify before you reach out:

• Inverter model and quantity (e.g., Goodwe GW10K-ET for a 10kW hybrid setup)
• Battery type and capacity (e.g., Lynx F series or ESA — specify kWh, not just "one battery")
• EV charger model and connector type (Type 2 for Australia/Europe, J1772 for North America)
• Smart meter model (like the GM3000) if required for export limiting or time-of-use optimization
• Mounting system and accessories (solar carport vs roof mount, cable lengths, isolation switches)
• Installation complexity (single-phase vs three-phase, new consumer unit needed?)

Avoid this mistake: In my first year, I asked for a "10kW system with battery backup." Vendor A quoted a GivEnergy inverter. Vendor B quoted a Goodwe. Vendor C quoted something else entirely. I spent 4 hours trying to compare specs that were never going to match. Now, I send a one-pager with model numbers. Takes 20 minutes to prepare, saves 4 hours of confusion.

Step 2: Get 3 quotes, but use a standard line-item template

Don't let each vendor decide how to structure their quote. Send them your template. I use a simple 12-line table:

1. Inverter unit price & quantity
2. Battery unit price & quantity
3. EV charger unit price & quantity (note: if you need a quote for Goodwe EV chargers quotes, ask for the specific model — the standard unit and the one with USB-C differ in price by about $180 as of Q1 2025)
4. Smart meter (if applicable)
5. Mounting kit & accessories
6. Cabling and connectors
7. Installation labor (hourly or fixed)
8. Electrical compliance certificate
9. Shipping / delivery
10. Warranty extension (if offered)
11. Any optional add-ons (smart home integration, monitoring portal, solar carport framing)
12. Total (including GST/VAT)

If a vendor refuses to break it down line by line, I flag that as a yellow flag. Not a hard pass, but I ask why. Sometimes the answer is reasonable ("we bundle accessories as a kit"). Sometimes it's not ("we just give a total price"). The vendor who lists all fees upfront — even if the total looks higher — usually costs less in the end.

Step 3: Identify hidden costs — the "what's NOT included" questions

I've learned to ask "what's not included" before asking "what's the price." Here's what I've found on at least 5 separate quotes (circa 2023–2024):

• Shipping to regional areas — A vendor quoted free shipping to a metro address, then added $420 for the last 80km to our regional site. That's not free shipping.
• Commissioning and software setup — Some vendors separate hardware delivery from the engineer's time to configure the inverter and app. This can be $250–$600.
• Battery cabling kit — The battery may ship without the interconnect cables. That Lynx F series battery does not include the power cable or comms cable in the box for some suppliers. Add $90–$150.
• Smart meter installation — The GM3000 might be included in the quote, but someone still needs to install and commission it. If your electrician hasn't done one before, expect a learning curve.
• Consumer unit upgrade — If the existing switchboard can't handle the new loads or doesn't meet current standards (AS/NZS 3000 for Australia), that's an extra $800–$1,500.

I built a "hidden cost checklist" that we now use for every quote. It's saved us roughly $4,200 in 2024 alone — money we would have just absorbed as "unexpected extras."

Step 4: Calculate total cost of ownership (TCO), not just upfront price

The cheapest quote upfront is almost never the cheapest after 3 years. Here's what I track:

Cost Factor	Why it matters
Warranty length & terms	Inverter warranty: standard 5 years, extended up to 10–12. Battery cycles: check the spec sheet for cycles at 80% DoD. A battery that needs replacement after 3,000 cycles vs 6,000 cycles is a different investment.
Monitoring subscription	Some inverters include free monitoring for 5 years. Others charge $50–$100/year after year 1. On a 10-year system, that's $450–$900.
Service availability	Is there a local service rep? Or do you ship the inverter back to a warehouse and wait 3 weeks for a replacement? Lost revenue from a down system: this is hard to quantify, but I estimate ~$150–$200/day for a commercial site without battery backup.
Upgrade path	Can you add more battery capacity later? The Goodwe ESA system supports daisy-chaining. Some brands don't, meaning you replace the whole unit.

Example from my spreadsheet: In Q4 2023, Vendor A quoted $11,200 for a 10kW inverter + 10kWh battery + 7kW EV charger. Vendor B quoted $10,900. Vendor A's quote included 10-year inverter warranty, free monitoring, and local depot (Perth). Vendor B's quote had 5-year warranty, $80/year monitoring, and required shipping to Sydney for repairs. TCO over 10 years: Vendor A = $11,200. Vendor B = $10,900 + $800 (extended warranty) + $800 (monitoring) + ~$600 (potential shipping for a repair) = $13,100. Vendor A was actually $1,900 cheaper over the system's life.

Step 5: Verify everything — model numbers, shipping dates, and compliance

Before you sign, run through this final checklist. I use a printed copy and tick each box:

• Model numbers match what you specified. I once ordered a "Goodwe GW10K-ET" and the vendor shipped a "GW10K-ES" — similar but not identical. Different DC/AC ratio, different battery compatibility. We caught it at the goods-in stage, but it was a 2-week delay.
• Shipping lead time is confirmed in writing. I always ask: "If I order today, what is the latest date I will receive the goods?" Not the average — the latest. I count from that date.
• Compliance with local standards. For Australia, that's AS/NZS 4777 (inverter grid connection) and AS/NZS 3000 (wiring). For voltage drop: check cable sizing for long runs — especially for a solar battery charger for electric fence applications on rural sites, which may require thicker gauge for the distance. Our standard is 2% max drop at full load.
• Delivery address and access. Can the courier get a pallet truck to the site? We had a quote that didn't specify "site has no forklift" — the vendor added $180 for a tailgate truck on delivery day.

My experience is based on about 200 mid-range orders (systems between $5k and $25k). If you're working on a massive commercial installation or a very low-budget residential system, your experience might differ. I can't speak to how this applies to grid-scale storage or off-grid-only setups — those have different procurement dynamics.

One final note: I still kick myself for not asking about the commissioning engineer's availability upfront. We once had a system sitting on site for 3 weeks because the certified electrician was booked out. Check that timeline before you commit to the delivery date. That $1,200 saving on hardware meant nothing when the client was waiting 21 extra days for their solar to be active.