Home batteries are bought for five different reasons, and the sizing logic differs for each. This page sets out the five deployment scenarios RUIDASIMAI systems are specified for, what each one demands of the battery, and what to check before committing to a configuration.
These are scenario patterns, not customer case studies. They describe how each application is approached; the configuration for a specific home depends on that home’s consumption profile and installation position.
1. Solar self-consumption
The situation. A rooftop array generates more than the house can use at midday, and the surplus is exported at a low feed-in rate. In the evening the household buys power back at the retail rate.
What the battery does. It absorbs the midday surplus and discharges it through the evening peak, so generation is consumed on site rather than sold cheap and bought back dear. The economics turn on the gap between the feed-in rate and the retail rate, multiplied by the kWh shifted each day.
What to check. The array’s output profile against evening demand — a battery sized far above the daily surplus will sit part-charged and never complete a full cycle, which wastes capital. Storage of roughly one day’s evening consumption is the usual starting point. See sizing a home battery.
2. Peak-rate and time-of-use saving
The situation. The household is on a tariff where electricity costs substantially more during defined peak hours, or where a demand charge is levied on the highest power drawn in a billing period.
What the battery does. Two distinct jobs. Under time-of-use pricing it charges on cheap off-peak power and discharges during the expensive window — arbitrage. Under a demand charge it discharges specifically to cap the site’s peak draw, which reduces the charge even if total kWh consumed barely changes.
What to check. The power rating, not just the capacity. Capping a peak requires the battery to supply a high load for a short period; a system with plenty of kWh but modest kW cannot do it. Check the continuous power figure the inverter can actually draw from the battery.
3. Whole-home backup
The situation. The grid is unreliable — storm exposure, an ageing distribution network, or a region with regular outages. The household wants essential circuits to keep running.
What the battery does. It supplies selected circuits when the grid fails and recharges when it returns. Backup is a different sizing problem from bill saving: it is driven by the duration of the longest credible outage and the load that must be carried through it, not by average daily consumption.
What to check. Three things. First, transfer time — the gap between grid loss and battery takeover, which determines whether sensitive equipment rides through. Second, which circuits are on the backed-up supply; whole-home backup needs the battery to cover motor starting loads such as pumps and compressors, which draw far more at start-up than in steady operation. Third, recharge capability — how quickly the battery refills between outages if the grid is intermittent.
Sizing note. A backup-focused installation is usually sized larger than a bill-saving one, because it must cover a worst case rather than an average.
4. Off-grid and weak-grid supply
The situation. There is no grid connection, or the connection is too weak or too intermittent to rely on — remote property, agricultural building, or a site awaiting connection.
What the battery does. It becomes the primary supply, with generation and storage sized against the worst period of the year rather than the average. Winter autonomy, not summer surplus, sets the capacity.
What to check. Autonomy days required, the load profile’s surge demand, and the recharge path — how many days of poor generation the system must absorb before it needs grid or generator support. Off-grid design is unforgiving of undersizing in a way grid-connected design is not.
5. Mobile and on-the-road power
The situation. The load moves: a vehicle, a mobile office, a workshop, or equipment that has to run away from any fixed supply.
What the battery does. It provides quiet, emission-free power where a generator would otherwise be needed, and can be recharged from solar, a vehicle alternator or a mains supply when one is available.
What to check. Ingress protection, because the installation is exposed to vibration and weather rather than a controlled utility room. An IP54 enclosure allows installation outside a dry indoor space. Also check the mounting method — mobile installations load the enclosure differently from a static one.
Matching the scenario to a form factor
- Self-consumption and peak saving — capacity follows daily shift, so a stackable system lets you start at the size you need and extend as the household changes.
- Whole-home backup — backup duration drives capacity upward, and a floor-mounted unit carries the highest capacity per enclosure.
- Off-grid — autonomy requirements push capacity furthest; parallel expansion matters because undersizing cannot be corrected by behaviour.
- Space-constrained retrofits — a wall-mounted unit keeps the floor clear where the only free position is a garage wall.
- Mobile — enclosure protection and mounting, not capacity, are the binding constraints.
Form-factor trade-offs are set out in choosing between stackable, wall-mounted and floor-mounted designs. Installation position requirements are covered in home battery installation location, and the certifications relevant to each market in home battery certifications.
Specifying a configuration
Where a standard model does not match the scenario — an unusual load profile, a non-standard installation position, or a specific capacity and voltage requirement — the system can be built to order. See customising a home battery for what can be specified and what is fixed by the underlying cell and safety design.
To have a configuration assessed for a particular property or application, send the load profile and installation constraints through the contact form.