Charge controllers (MPPT)

How to use this table

This table holds 15 charge controllers (mppt) normalized onto the same columns, so that units described differently by their manufacturers can be compared directly. Every row carries a confidence flag and a link to the datasheet or retailer page the figures came from, and every product has its own page with the numbers worked through for an off-grid build.

What is in here right now

The charge controllers (mppt) listed run from 30 to 100 A, with a median of 60 A. The median price works out at about $5.15 /A per unit, which is the figure worth comparing against rather than the sticker price.

Sort on any column by clicking its header. The comparison that usually settles a decision is not the biggest number but the price per unit alongside the specification that constrains your design, because that is where a cheaper product either is or is not a false economy.

What each column means

A

The most current the pack will accept. It sets how fast a bank can recover and how large an array or charger can usefully be pointed at it.

Batt V

The battery voltage the unit works with, which constrains the whole system.

Max PV V

Absolute maximum photovoltaic input voltage. Exceeding it destroys equipment immediately, and cold weather is how people exceed it.

PV W @12

Array wattage the controller supports on a 12 V bank. Current is the limit, so the same controller carries far more at higher voltage.

PV W @24

Array wattage supported on a 24 V bank.

PV W @48

Array wattage supported on a 48 V bank.

Eff %

Watts per unit of area. It matters when space is the constraint and matters much less on open ground.

Comms

Which communication protocols the battery speaks. A supported protocol lets the battery manage its own charge profile and report real state of charge to the inverter.

Wty yr

Warranty length. How a claim is actually handled matters more off grid than how long the term is.

Price

List or recorded retail price at the date noted. Prices move constantly.

$/A

Price normalized to the unit that allows fair comparison across different sizes.

A workable way to shortlist

Start with the array you plan and the system voltage you have chosen, which together give the charge current required. Check the input voltage ceiling against your coldest morning with margin, because that limit destroys equipment outright. Then look at configurability and monitoring, which is where controllers differ in service rather than on the datasheet.

Then read the individual product pages, which work each unit's published numbers through for an off-grid build and list the nearest alternatives in this table. The system planner sizes array, controller, battery, and inverter against each other rather than one at a time, which is how these choices actually interact.

Five ways people get this purchase wrong

1. Designing the string from the panel datasheet alone. The number that matters is open-circuit voltage at your site's coldest temperature, with margin on top.
2. Choosing on conversion efficiency rather than on tracking quality. How well a controller finds the true peak under moving cloud decides real harvest more than a percentage point on the datasheet.
3. Leaving a generic lithium preset in place instead of entering the battery manufacturer's own charge figures.
4. Mounting it in direct sun or without ventilation, then wondering why it derates in July.
5. Buying a second controller when raising the system voltage would have solved the same problem and thinned every conductor in the system.

Every one of those is cheaper to avoid than to fix, and most of them are decided before anything is bought. That is the argument for building the load list and the system design first and shopping second, which is what the planner and the course are for.

Where these numbers come from

Figures are transcribed from manufacturer datasheets or primary retailer specification pages, recorded with a date and a confidence flag, and linked back to the source on each product page. Where a manufacturer publishes a figure without its test conditions, it is recorded as published and treated with the skepticism it deserves rather than quietly normalized.

Prices are list or observed retail at the date noted and move constantly, so they are here for the ratio rather than for the last dollar. The price index tracks market ranges over time, the open data page publishes these tables as CSV and JSON, and the methodology page sets out how the research is done. If a figure here no longer matches its source, the corrections page is how to say so; corrections are logged publicly rather than edited away.

Missing a product you are comparing? Tell us and it goes on the list. The tables grow from what readers are actually shopping for rather than from what is easiest to transcribe.

Common questions about charge controllers (mppt)

MPPT or PWM?
For anything but a very small system, a maximum power point tracker. It extracts more from the same array, and the advantage is largest in cold weather and in winter, which is exactly when an off-grid system is short. A simpler controller is defensible only where the array is tiny and the panel voltage closely matches the battery.

How do I know how many panels I can put in series?
Divide the controller's maximum input voltage by the panel's open-circuit voltage, then reduce the result for cold weather, because panel voltage rises as temperature falls. Work it from the panel's voltage temperature coefficient and your site's design low, then leave margin. Exceeding the ceiling can destroy the controller instantly.

Can one controller be too big for my battery?
It can push more current than the bank should accept, in which case the battery management system limits it, which is workable but means you paid for capacity you cannot use. Match the controller to the array you plan and to what the bank will take.

Why is my array producing less than it should?
In order of likelihood: shading that you have not noticed at the time of day or year it matters, a string that has dropped out, soiling, voltage drop in the array run, or a tilt that suits summer rather than winter. The controller's own logging is usually the fastest way to tell which.

Do I need one controller per array orientation?
If the arrays face meaningfully different directions or shade at different times, separate trackers extract more, because a single tracker has to compromise between them. Many controllers include more than one tracker for this reason.

Listings, inspection, and insurance

Safety listings are easy to skip past on a spec sheet and hard to add afterwards. Where a jurisdiction inspects an off-grid installation, unlisted equipment can fail the inspection outright. Where nobody inspects, insurers may still ask, and an appliance or a system component without a recognized listing is a reason some carriers give for declining a rural policy or a claim.

That matters more off grid than on, because rural policies are already a narrower market. Insurers commonly ask what the structure is, how it is heated, how far it is from a responding fire station, and whether the installation was permitted and inspected. Deciding to buy listed equipment and to hold the installation to code standards, even where nobody will check, is the cheapest form of that conversation going well.

Keep the paperwork with the systems binder: model and serial numbers, the datasheet as it read on the day you bought, the installation photographs before anything was closed up, and the receipts. Proving what you had is your job in a claim, and it is also what makes a sale straightforward years later. Lesson eleven covers the insurance and financing side, and the printable binder has a place for all of it.

This category inside a whole system

No component in an off-grid power or water system is chosen alone. The battery constrains the inverter, the inverter constrains the cable and the fusing, the controller constrains the array, the array is constrained by the worst month at your location, and the whole thing is constrained by the load list you started with. Choosing any one part in isolation is how people end up buying twice.

The order that works is: honest load list, then location data, then system voltage, then the components against each other, then the wiring and protection that make it safe. Lesson four covers the load list, the site report gives the location numbers for any address, the planner sizes the components as a set, and lesson six covers the part where mistakes start fires rather than merely costing money.

The other tables are next door: batteries, panels, inverters, controllers, generators, and pumps. For prices rather than specifications, the price index; for what to keep on the shelf, the spares reference; for the terms used here, the glossary.