Martin and Julie Johnson built a self-sufficient homestead on seven acres in Northern Idaho, funding the project without a loan and paying cash for components, much of which were second-hand. Their system began with a four-panel, ground-mounted solar installation and was later expanded with two Astronergy panels, a Midnite Classic charge controller, and a Victron battery monitor.
Their approach is useful as a planning case: start with a load audit, build the power system in stages, and match water storage and treatment to the property’s actual risks. In Australia, the same principles apply, but the climate, voltage, rainfall, fire exposure, and water-treatment requirements at a Central Queensland site must drive the design.
Johnson Homestead System Overview
| Item | Verified information | Planning implication |
|---|---|---|
| Property | Seven acres in Northern Idaho | The Johnsons’ original installation is a case study, not a template for every property. |
| Initial solar | Four ground-mounted panels installed by Martin | A modest first stage can establish the basic power system. |
| Expansion | Two additional Astronergy panels | Check array voltage, current, connector, and charge-controller compatibility before expansion. |
| Charge control | A Midnite Classic charge controller was added | The source does not confirm the 250 V model for their actual installation. |
| Battery monitoring | A Victron battery monitor was added | Monitoring supports battery maintenance and helps identify changes in available energy. |
| Battery chemistry | Lead-acid batteries | Their stated priority was repairability rather than brand recognition. |
| Funding | No homestead loan; components paid for in cash, much of it second-hand | Staged procurement can reduce the amount of borrowed capital required. |
| Documentation | The Johnsons are filmmakers who documented the installation and lifestyle on YouTube | Their material provides a record of the system’s development. |
The source listed a Midnite Solar Classic MPPT Charge Controller 250V at $845.63 and a Victron Energy Smart BMV-712 at $230.00. These are historical listed prices from the cited source, not current Australian prices. A buyer in Australia should obtain current quotes and confirm that equipment is appropriate for 230 V, 50 Hz operation and the selected battery chemistry.
Start With the Load Audit
A battery bank should be sized from the loads it must supply, not from a preferred battery model. Record every appliance and its daily use:
- Rated power in watts
- Hours operated per day
- Daily energy consumption in watt-hours
- Whether the load is essential during cloudy weather
- Whether it can be scheduled for times when solar production is strongest
Daily energy is calculated as:
watts × hours per day = watt-hours per day
Add the daily requirements, then include an appropriate reserve for the intended number of days without adequate solar input. The facts sheet does not provide a verified depth-of-discharge figure for the Johnsons’ bank, so a specific autonomy period should not be claimed for their installation.
Lead-acid batteries generally have a lower usable proportion of nominal capacity than lithium iron phosphate batteries. A common planning comparison is approximately 50% usable capacity for lead-acid versus 80% for LiFePO4. That does not mean every battery can safely be discharged to those levels; the manufacturer’s limits and the selected system design take precedence.
Battery Chemistry and Configuration
The three lead-acid variants identified for off-grid use are flooded lead-acid, AGM, and gel. They differ in cost, maintenance, and cycle-life characteristics.
Flooded lead-acid
Flooded batteries are repairable in the broad sense that individual serviceable components and battery maintenance practices are more accessible than with a sealed product. Their main requirements are:
- A vented space
- Shade
- Routine water-level inspection
- Terminal inspection for corrosion
- A charging regime suited to the battery manufacturer’s instructions
Flooded batteries can release hydrogen during charging. Hydrogen accumulation creates an explosion risk if ventilation is inadequate or ignition sources are nearby.
AGM and gel
AGM and gel batteries reduce some of the watering and access requirements associated with flooded cells. Gel batteries are particularly sensitive to overcharging and require a charge profile matched to their chemistry.
No verified information identifies the exact Johnson battery arrangement, such as series voltage, parallel count, nominal capacity, inverter rating, or charge settings. Those details should not be inferred from the source material.
Battery Bank Requirements
| Requirement | Practical requirement |
|---|---|
| Ventilation | Provide airflow around the battery bank; flooded batteries require a vented space because charging can release hydrogen. |
| Temperature control | Locate batteries in shade. Heat can shorten battery life. |
| Inspection | Inspect monthly for water levels and terminal corrosion. |
| Monitoring | Use a suitable battery monitor to track the bank’s state and charging behaviour. |
| Compatibility | Match the charge controller, battery monitor, array, inverter, and battery voltage before connection. |
| Expansion | Check electrical ratings and charge limits before adding panels or batteries. |
| Protection | Keep ignition sources, loose metal, and unsuitable storage away from the battery area. |
| Documentation | Record the battery chemistry, nominal voltage, capacity, wiring arrangement, and manufacturer settings. |
A lead-acid bank should not be expanded merely by adding more batteries. The existing bank’s voltage, capacity, age, condition, and the inverter and charger limits all affect whether expansion is sensible. Adding equipment without verifying those factors can cause poor charging, reduced usable capacity, or damage.
Solar and Battery Stages
The Johnsons began with four panels and later added two panels, a charge controller, and a battery monitor. Their staged approach demonstrates why compatibility matters at every stage:
1. Measure the load and identify essential and discretionary loads.
2. Establish the solar array and charge control.
3. Select the battery chemistry and nominal bank voltage.
4. Add the inverter and battery monitor.
5. Expand only after checking the complete system.
6. Schedule pumps and other heavy loads when solar production is strongest.
Running heavy loads around midday can align consumption with periods of higher solar output and can suit a lead-acid solar bank’s recovery profile. It is not a substitute for adequate battery sizing.
Water Storage Planning
Rainwater capture is an important supply strategy for many rural Australian properties. Storage should be planned as a complete system:
- Roof catchment area
- Gutter and downpipe collection
- First-flush diversion
- Screening or filtration
- Covered tank
- Pump and pressure system
- Treatment appropriate to the intended use
- Backup supply where site conditions justify it
A first-flush diverter can improve rainwater quality by diverting the initial runoff that may contain debris and contaminants collected since the previous rain. Rainwater should still be treated before drinking, commonly through an appropriate UV or chlorination process, subject to the treatment equipment’s instructions and local guidance.
A bore or dam may provide a site-dependent backup, but the available source, water quality, pumping requirements, storage volume, and treatment needs must be assessed. The fact sheet does not verify that the Johnsons used a bore, dam, specific tank size, or a particular treatment system.
Australian System Requirements
A Central Queensland installation must be designed for Australian conditions and the local site. Relevant planning questions include:
- Is the system intended to run at 230 V and 50 Hz?
- Will the battery bank operate in a shaded, ventilated enclosure?
- Can the tank and pump be installed and maintained safely?
- Is drinking water protected from contamination after collection and storage?
- Is there a fire or heat-management consideration around batteries, cables, pumps, and storage?
- Will the system remain functional during prolonged cloudy periods or high electrical demand?
The supplied canon places the practitioner in Beecher, Central Queensland, and uses Australian metric, electrical, and currency conventions. The Johnson case itself remains based in Northern Idaho; the Australian application should be treated as an adaptation, not as a claim that the Johnsons live in Queensland.
Safety
Lead-acid battery banks require airflow, shade, and monthly inspection. Check water levels in flooded batteries and inspect terminals for corrosion. Heat and inattention can cause premature failure.
Flooded lead-acid batteries must be kept in a vented space because they can release hydrogen gas during charging. Never introduce flames, sparks, or ignition sources into the battery area. Use suitable tools and electrical protection, and prevent metal objects from bridging battery terminals.
Gel batteries require a charge profile matched to their chemistry. Overcharging can damage them, so the controller and battery settings must be verified.
When expanding an existing solar array, check the panels, charge controller, and battery monitor for compatibility. Confirm voltage and current ratings, wiring, fusing, and charging limits before adding equipment.
When to call a licensed professional
Use a licensed professional for:
- Grid-connected or mains-voltage electrical work
- Inverter and battery-bank installation where required by Australian law
- Work on fixed wiring, protective devices, or circuits connected to 230 V equipment
- Battery systems involving hazardous energy, damaged batteries, or uncertain wiring
- Pump, pressure-system, or rainwater work involving mains plumbing
- Any work that cannot be safely isolated, tested, and completed within your competence
A professional should also review the design when multiple battery strings, an expansion, or a system using unfamiliar charging equipment is proposed. Local electrical and plumbing requirements vary, and licensing requirements should be checked before work begins.
Frequently Asked Questions
Why did the Johnsons choose lead-acid batteries?
Their battery bank uses lead-acid batteries chosen for repairability over brand recognition. The source does not specify a detailed comparison of individual brands or models.
How much battery capacity is needed?
Capacity depends on the daily load, the number of days the system must operate without adequate solar input, battery chemistry, and usable depth of discharge. Begin with a load audit in daily watt-hours. The Johnson source does not provide a verified capacity for its bank.
Should batteries be installed indoors?
Flooded lead-acid batteries must be installed in a vented space. They also need shade, airflow, monthly inspection, and protection from ignition sources. The exact enclosure depends on the battery type, site, and applicable requirements.
Can rainwater be used for drinking?
A first-flush diverter can improve rainwater quality, but rainwater should still be treated, commonly using UV or chlorination where appropriate, before drinking. The treatment method must suit the intended use and the water system.
Can the system be expanded later?
Yes, but the complete system must be checked before expansion. Confirm that the added panels, charge controller, battery monitor, wiring, inverter, and batteries are compatible. The Johnsons’ expansion provides a useful example of staged development, not a universal electrical design.
Why schedule heavy loads for midday?
Solar production is generally strongest around midday. Running pumps and other heavy loads during that period can align demand with generation and can support a lead-acid solar bank’s recovery profile. The load should still be included in the initial load audit.
Sources
- Unbound Solar: Martin & Julie Johnson Customer Installation
- OffGrid Masterplan: Johnson Off-Grid Solar Battery Bank and Water Storage
Worth a watch: TOTAL COST Of Our Off-Grid Solar Power System | Powering Our Mountain Home · Ambition Strikes
Frequently asked questions
Should I use lithium or lead-acid batteries for off-grid solar in Queensland?
Not from where I sit - I've had three LiFePO4 banks cook out on me in the Queensland heat, and I now run flooded lead-acid for my own off-grid water pumping setup. Lead-acid handles the heat better and costs a fair bit less up front, which matters when you're trying to keep the build debt-free. Lithium's a great battery in cooler climates, but up here in central QLD I'd sooner trust a flooded cell to keep going.
How big do my water tanks need to be in central Queensland?
You size for the longest dry stretch you'll actually face, not the average year - central QLD dry spells can drag on for months. I'd rather oversize once than run a household on fumes halfway through summer. The trick is matching tank capacity to your roof catchment and what your family genuinely uses day to day, then building up from there.
How can I go off-grid without going into debt?
Short answer is buy what you can pay cash for and add on in stages - Martin's place is proof you don't need a big loan to get there. I started with a basic lead-acid bank and a couple of tanks, then bolted on solar and extra storage as the money came in. Building it up in chunks keeps the debt off your back and forces you to actually learn the system as you go.
What does a cooked lead-acid battery bank smell like?
You'll know the second you step in the shed - it's a sharp, acrid, almost rotten-egg chemical stench that hits you before you're properly awake. By 4am it's usually because something's been overcharging or the cells have gone dry. The moment I catch that whiff I'm cracking the shed doors wide open and walking the bank cell by cell.